Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/tmech.2023.3290970

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

High-efficiency plasma skimming is hopeful to prevent hemolysis inside spiral groove bearings (SGBs) because it can exclude red blood cells from the ridge gap with a high shear force. However, no study reveals the shape design of SGBs to improve plasma skimming. Therefore, this study proposed and applied a groove design strategy to designing an optimal SGB for enhancing plasma skimming in a rotary blood pump (RBP). Initially, we proposed the design strategy that the shape of the groove for enhancing plasma skimming corresponds to the direction of blood flow in the ridge gap. Second, we visualized the cell flow in a specially designed experimental RBP to determine the direction of blood flow, which was helpful in the subsequent SGB design. Then, we created an SGB to provide superior plasma skimming and applied it to the experimental RBP. We evaluated the plasma skimming effect of SGB at rotational speeds ranging from 2400 to 3000 rpm and hematocrit conditions between 1% and 40%. At a 1% hematocrit, the plasma skimming efficiency for the entire SGB was greater than 95%. In all hematocrit conditions, the efficiency at the inner ridges of the SGB was greater than 80%. The results showed the designed SGB successfully induced excellent plasma skimming within ridge gaps. This study is the first to propose and apply a shape design strategy to generate excellent plasma skimming within an SGB. This study may contribute to the prevention of SGB hemolysis inside SGB for use in RBPs.

DOI： 10.1007/s10047-023-01422-y

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electrical Engineers of Japan  

Wireless power transfer based on magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies significantly and, in case of impedance mismatch, power reflection may occur. To address this issue, we employed a driver coil on the transmitter side to match input impedance. By regulating the coupling coefficient between the driver and the transmitter coils, the input impedance is matched and power reflection is eliminated. Input impedance regulation is achieved by moving the driver coil mechanically. As confirmed by our experiments, the transmitting efficiency matched with the analytically calculated value, and the input impedance was matched for a vast range of distances from 0 to 1m and load resistances from 4 to 210 Ω by moving the driver coil properly. Therefore, the proposed system successfully addresses the power reflection problem in wireless power transfer for mobile robots.

DOI： 10.1541/ieejjia.22009525

DOI： 10.1541/ieejjia.24002906_references_DOI_KWVpXK74KxGuuRoDcRdFltO9FCm

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For the practical application of bio-actuators, it is desired to develop a precise control method for skeletal muscles. In this study, a novel model-based control method has been proposed. The control method enables skeletal muscles to exert an arbitrary magnitude of contraction force, rather than just the conventional on/off control. First, we proposed a control system to obtain the optimized electrical stimulation voltage, that can reproduce reference force. In order to actually apply the method, a bio-actuator consisting of a skeletal muscle of a frog was manufactured for a verification experiment. First, muscle contraction model parameters that could reproduce the contractile response of the gastrocnemius muscle were identified from the experimental data. Next, based on this model, the proposed control method was used to calculate the stimulation voltage to exert the reference force. The voltage was applied to the bio-actuator to control the contraction force. As a results, the output of the actuator was able to follow the stepwise reference force. Our proposed control method demonstrates the feasibility of precise control of bio-actuators.Clinical Relevance- If skeletal muscles could be used as actuators for power-assistive suits, it would be possible to develop power-assistive suits that are more compatible with people and reduce the burden on caregivers in the field of nursing care. The method proposed in this study will enable the control of skeletal muscle contraction force by electrical stimulation, bringing skeletal muscle actuators closer to practical application.

DOI： 10.1109/EMBC40787.2023.10341011

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Language：Japanese  

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I032956708

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BACKGROUND: Mechanical circulatory support devices, such as left ventricular assist devices, have recently been used in patients with heart failure as destination therapy but the formation of thrombus in blood pumps remains a critical problem. In this study, we propose a mechanical antithrombogenic method by impeller excitation using a magnetically levitated (Maglev) centrifugal pump. Previous studies have shown that one-directional excitation prevents thrombus; however, it is effective in only one direction. In this study, we aimed to obtain a better effect by vibrating it in a circular orbit to induce uniform changes in the shear-rate field entirely around the impeller. METHODS: The blood coagulation time was compared using porcine blood. (1) The flow rate was set to 1 L/min, and applied excitation was at a frequency of 280 Hz and amplitude of 3 μm. (2) Moreover, the effect was compared by varying the frequency, amplitude, and direction of the excitation. In this experiment, the flow rate was set to 0.3 L/min. RESULTS: (1) The thrombus formation time was 77 min without excitation and 133 min with excitation, which was 1.7 times longer. (2) The results showed no difference between (280 Hz, 3 μm) and (50 Hz, 16 μm) circular orbital excitations, and no directional difference, with thrombus formation of 2.5 times longer under all conditions than that without excitation. CONCLUSION: In the case of simple reciprocating excitation, the time was approximately 1.2 times longer. This indicated that the circular orbital excitation is more effective.

DOI： 10.1111/aor.14443

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BACKGROUND: Antithrombogenicity of extracorporeal membrane oxygenation (ECMO) devices, particularly oxygenators, is a current problem, with numerous studies and developments underway. However, there has been limited progress in developing methods to accurately compare the antithrombogenicity of oxygenators. Animal experiments are commonly conducted to evaluate the antithrombogenicity of devices; however, it is challenging to maintain a steady experimental environment. We propose an innovative experimental animal model to evaluate different devices in a constant experimental environment in real-time. METHODS: This model uses two venous-arterial ECMO circuits attached to one animal (one by jugular vein and carotid artery, one by femoral vein and artery) and real-time assessment of thrombus formation in the oxygenator by indocyanine green (ICG) fluorescence imaging. Comparison studies were conducted using three pigs: one to compare different oxygenators (MERA vs. CAPIOX) (Case 1), and two to compare antithrombotic properties of the oxygenator (QUADROX) when used under different hydrodynamic conditions (continuous flow vs. pulsatile flow) (Cases 2 and 3). RESULTS: Thrombi, visualized using ICG imaging, appeared as black dots on a white background in each oxygenator. In Case 1, differences in the site of thrombus formation and rate of thrombus growth were observed in real-time in two oxygenators. In Case 2 and 3, the thrombus region was smaller in pulsatile than in continuous conditions. CONCLUSIONS: We devised an innovative experimental animal model for comparison of antithrombogenicity in ECMO circuits. This model enabled simultaneous evaluation of two different ECMO circuits under the same biological conditions and reduced the number of sacrificed experimental animals.

DOI： 10.1111/aor.14380

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Language：English   Publisher：The Japan Society of Applied Electromagnetics and Mechanics  

Wireless power transfer via magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies greatly and power reflection occurs in case of impedance mismatch. Therefore, we propose the use of multiple identical driver coils on the transmitter side in order to match the input impedance. The input impedance is matched and power reflection is eliminated by switching driver coils, i.e., regulating the coupling coefficient between the driver and the transmitter. In addition, the winding number of the receiver coil can be switched to relax the design condition of the drive coil. The experimental results showed the input impedance was well-matched automatically under the varying distance and load resistance. Therefore, the proposed system was expected to solve the power reflection issues in practice.

DOI： 10.14243/jsaem.31.90

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

In addition to the characteristics of soft actuators, such as flexibility and elasticity, biohybrid actuators also exhibit few distinctive functions, such as self-growth and self-healing. The previous research on biohybrid actuators has focused on culturing muscle cells and assembling them into micro-robots. These technologies are well-developed, however they lack the design and control methods found in the existing actuators that enable an appropriate performance. Therefore, we propose a simple muscle contraction model against external electrical stimulation, applying the model-based design and realizing the control of biohybrid actuators. The model comprises three sub-models—the electrical dynamic, physiological, and mechanical dynamic characteristics. The input of the model is the time-series stimulation voltage, and therefore, it can be applied to any complex stimulation waveform. The model parameters were identified with multiple square waves with different frequencies and amplitudes, based on the actual skeletal muscle of a toad. Subsequently, in the validation test, the actual muscle contraction was compared with the simulated force that was calculated using the identified parameters. Although the stimulations for the validation were different from those for the identification, the results obtained based on the model showed a good agreement with the experimental results. In addition, the optimal stimulation signal could be also calculated based on the model, to obtain the maximum net work. The findings of this study facilitate the development of model-based design and control methods for biohybrid actuators in the future, that will lead to significant development in this field.

DOI： 10.1299/jbse.22-00269

DOI： 10.1299/jbse.24-00254_references_DOI_Fle6OPD0nlS98NXe3SgFTFrLFAK

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MYU K.K.  

DOI： 10.18494/sam4134

DOI： 10.1299/jbse.23-00590_references_DOI_ECx1MmQxxsA3OBfGg7L05oT2RSl

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Plasma skimming can exclude red blood cells from high shear regions in the gaps formed by hydrodynamic bearings in rotary blood pumps. We investigated the effect of the gap size and groove design on the plasma skimming efficiency. Spiral groove bearings (SGBs) were installed into a specially designed test rig for in vitro experiments performed using human blood. The measured gap between the ridges of the bearing and the rotor surface was 17-26 µm at a flow rate of 150 ml/min and a rotor speed of 2400 rpm. Three different patterns of SGBs were designed (SGB-0, SGB-30, and SGB-60) with various degrees of the circumferential component. The hematocrit measured by a high-speed camera was compared with the hematocrit in the circuit, and the plasma skimming efficiency for the three bearing patterns was evaluated at hematocrits of 20%, 25%, and 30%. SGB-60, which had the strongest circumferential component, provided the best plasma skimming efficiency. When the gap size was less than 20 µm, the red blood cells in the gaps between the ridges of the bearing and rotor surface reduced significantly and the efficiency became higher than 90%. The gap size had the strongest effect on producing a significant plasma skimming. The plasma skimming efficiency can be significantly improved by optimizing the bearing gap size and groove design, which facilitates the further development of SGBs for use in applications such as rotary blood pumps.

DOI： 10.1007/s10047-021-01308-x

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.nanoen.2022.107357

DOI： 10.2139/ssrn.4071777

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Publishing type：Research paper (scientific journal)   Publisher：World Scientific Pub Co Pte Ltd  

<jats:p> To develop a power generation system as a solution to the power supply problems of small active implantable medical devices, we proposed a new method to examine muscles using skeletal muscle contraction through electrical stimulation. Realization of the system requires data on the contraction characteristics of a part of the muscles through which blood flows; thus, a dedicated setup was built and verified using a goat. The connecting parts were attached to two points in the large muscle of the goat’s trunk; one was fixed and the other slid along the guide. The distance and force between the two points, approaching each other, were measured by contracting the muscle between the points using electrical stimulation and pulling the measurement cart. The contraction distance and force were measured simultaneously, and the dynamic work of the contraction was calculated. The muscle work occurred with almost the same time delay regardless of the load, and the work tended to be greater when the contraction force, and not the contraction distance, of the muscle was large. The setup is physiological, simple, and versatile. Our setup can potentially be used in the development of implantable power generation systems and in other related fields. </jats:p>

DOI： 10.1142/s0219519422500075

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

For circulation support in patients with heart disease, a miniaturized implantable ventricular assist device (VAD) is required. However, several issues such as hemolysis and miniaturization need to be addressed. The objective of this study is to develop a passive levitation system for an impeller with a large gap without active control. The large gap prevents blood damage, and passive levitation contributes to the miniaturization of the VAD. In this study, a new passive levitation system utilizing thrust and magnetic force is proposed. The thrust generated by the rotation of the impeller changes depending on the interaction between the housing geometry and impeller position, even with a large gap. Considering this characteristic, the impeller was levitated by balancing the magnetic force generated by the permanent magnets and the thrust in the axial direction. The movements in the radial and angular directions are passively supported by the restoring force and torque generated by the permanent magnets. The thrust was calculated using computational fluid dynamics, and the pump was designed such that the thrust changes according to the axial displacement of the impeller. The magnetic force generated by the permanent magnets was calculated using finite-element method 3D magnetic field analysis. In addition, the required current density flowing into the coil to rotate the impeller is calculated. The levitation of the impeller was confirmed by combining the results of the analyses. The results show that the motor torque should be improved. In conclusion, this study demonstrates the feasibility of a novel levitation system for implantable miniaturized VADs.

DOI： 10.1299/jamdsm.2022jamdsm0025

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Acquired von Willebrand syndrome (AVWS), characterized by reduced von Willebrand factor (VWF) large multimers, has recently been implicated as the principal mechanism underlying bleeding in patients implanted with left ventricular assist devices (LVADs). Hematological severity of AVWS varies among patients, even if an identical device is implanted. We investigated whether this diversity in hematological severity is due to individual variability in VWF fragility, according to responses to incremental shear stress. Whole-blood samples were sheared at 20,000-40,000 s-1 shear rate, an index of shear stress, using a custom-made shear stressor that could generate shear stress compatible with that produced by an LVAD. The degree of VWF large multimers degradation was evaluated using the VWF large multimer index. A significant inverse correlation was observed between the VWF large multimer index and LVAD-compatible magnitudes of shear stress: the VWF large multimer indices were 68.5 ± 18.3, 48.0 ± 13.9, 33.9 ± 12.1, 23.7 ± 7.9, and 18.7% ± 8.7% at 20,000, 25,000, 30,000, 35,000, and 40,000 s-1 of shear rates, respectively (P < 0.0001). Furthermore, experimental VWF large multimer index values were compatible with those derived from patients with implanted LVADs (median; 28.9%). Finally, reduction in the VWF large multimer index corresponding to shear stress showed individual variation. We demonstrated that the combined use of a novel high shear stress loading device and quantitative evaluation of VWF large multimers may predict risk of bleeding before LVAD implantation.

DOI： 10.1097/MAT.0000000000001623

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Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/embc46164.2021.9629535

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We have been developing an implantable power generation system that uses muscle contraction following electrical stimulation as a permanent power source for small implantable medical devices. However, if the muscle tissue is overloaded for power generation, the tissue may rupture or blood flow may be impaired. In this study, we developed a new muscle-connecting component that solves these problems. The new connection device has three rods attached to the muscle fibers, and the force exerted on the muscle fibers is converted from horizontal to vertical when the muscle contracts. We conducted simulations with a three-dimensional (3D) model, as well as pulse wave muscle measurements and in vivo tests using the actual muscle. The pulse wave in the connecting part and its downstream were optically measured from the muscle surface, and the blood flow was not obstructed. The 3D model simulations revealed that the distribution of stress was preferable compared with the case in which a rod was stuck vertically in the muscle. In the in vivo muscle tests, the metal rod and resin parts were attached to the muscle, and a load of up to approximately 9 N was applied to the connecting part. Consequently, the connecting part was stable and integrated with the muscle, and there was no damage in the muscle. Although no long-term or histological evaluations were conducted, the device may be useful because of the intramuscular power generation owing to the minimal load applied on the part connected with the muscle.

DOI： 10.1109/EMBC46164.2021.9629561

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Extracorporeal membrane oxygenation (ECMO) plays an important role in the coronavirus disease 2019 (COVID-19) pandemic. Management of thrombi in ECMO is generally an important issue; especially in ECMO for COVID-19 patients who are prone to thrombus formation, the thrombus formation in oxygenators is an unresolved issue, and it is very difficult to deal with. To prevent thromboembolic complications, it is necessary to develop a method for early thrombus detection. We developed a novel method for detailed real-time observation of thrombi formed in oxygenators using indocyanine green (ICG) fluorescence imaging. The purpose of this study was to verify the efficacy of this novel method through animal experiments. The experiments were performed three times using three pigs equipped with veno-arterial ECMO comprising a centrifugal pump (CAPIOX SL) and an oxygenator (QUADROX). To create thrombogenic conditions, the pump flow rate was set at 1 L/min without anticoagulation. The diluted ICG (0.025 mg/mL) was intravenously administered at a dose of 10 mL once an hour. A single dose of ICG was 0.25mg. The oxygenator was observed with both an optical detector (PDE-neo) and the naked eye every hour after measurement initiation for a total of 8 hours. With this dose of ICG, we could observe it by fluorescence imaging for about 15 minutes. Under ICG imaging, the inside of the oxygenator was observed as a white area. A black dot suspected to be the thrombus appeared 6-8 hours after measurement initiation. The thrombus and the black dot on ICG imaging were finely matched in terms of morphology. Thus, we succeeded in real-time thrombus detection in an oxygenator using ICG imaging. The combined use of ICG imaging and conventional routine screening tests could compensate for each other's weaknesses and significantly improve the safety of ECMO.

DOI： 10.1111/aor.13999

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Blood pumps are often used for hemofiltration in patients with renal failure. To design effective centrifugal blood pumps for hemofiltration, it is important to suppress clogging caused by platelet aggregation. However, the optimal conditions for conducting anti-platelet aggregation tests in vitro have not yet been established. This study aimed to quantify the effect of the shear loading value and shear loading time on platelet aggregation and determine the optimal conditions for anti-platelet aggregation testing in vitro. To quantitatively evaluate platelet aggregation in terms of the negative logarithm-platelet aggregation threshold index (NL-PATI), which reflects the propensity of residual platelets to aggregate after shear loading, the following parameters were examined: blood collection method (collected from porcine vein using a syringe or collected from a slaughterhouse), type of anticoagulant (sodium citrate or heparin), shear rate, and shear time. The results showed that platelet aggregation in porcine blood increased under a high shear load applied at shear rates of approximately 20,000 s-1 or higher for 30 s. Platelet aggregation propensity was 2-3 times higher in heparin-anticoagulated blood than in sodium citrate-anticoagulated blood. Moreover, platelet aggregation was 1.5-2 times more in blood collected from the slaughterhouse than in syringe-collected blood. Testing with an integrated shear time of 30 s or less in relation to the total blood volume may be effective for conducting in vitro circulation experiments using hemofiltration blood pumps. The conditions established in this study may be useful for hemocompatibility testing of cardiovascular devices based on NL-PATI.

DOI： 10.1177/03913988211020765

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Pump thrombosis induces significant complications and requires timely detection. We proposed real-time monitoring of pump thrombus in a magnetically levitated centrifugal blood pump (mag-lev pump) without using additional sensors, by focusing on the changes in the displacement of the pump impeller. The phase difference between the current and displacement of the impeller increases with pump thrombus. This thrombus detection method was previously evaluated through simulated circuit experiments using porcine blood. Evaluation of real-time thrombus detection in a mag-lev blood pump was performed using a porcine left ventricular assist circulation model in this study. Acute animal experiments were performed five times using five Japanese domestic pigs. To create thrombogenic conditions, fibrinogen coating that induces thrombus formation in a short time was applied to the inner surfaces of the pump. An inflow and an outflow cannula were inserted into the apex of the left ventricle and the carotid artery, respectively, by a minimally invasive surgical procedure that allowed minimal bleeding and hypothermia. Pump flow was maintained at 1 L/min without anticoagulation. The vibrational frequency of the impeller (70 Hz) and its vibrational amplitude (30 μm) were kept constant. The thrombus was detected based on the fact that the phase difference between the impeller displacement and input current to the magnetic bearing increases when a thrombus is formed inside a pump. The experiment was terminated when the phase difference increased by over 1° from the lowest value or when the phase difference was at the lowest value 12 hours after commencing measurements. The phase difference increased by over 1° in three cases. The pump was stopped after 12 hours in two cases. Pump thrombi were found in the pump in three cases in which the phase difference increased by over 1°. No pump thrombus was found in the other two cases in which the phase difference did not increase. We succeeded in real-time thrombus monitoring of a mag-lev pump in acute animal experiments.

DOI： 10.1111/aor.13915

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Publisher：ACM  

DOI： 10.1145/3460238.3460256

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DOI： 10.1111/aor.13743

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The use of contactless support technology for the impeller has led to an increase in the durability of ventricular assist devices (VADs), and these have been in clinical use worldwide. However, pump thrombosis and stroke are still issues to be solved. We have developed a method for detecting the thrombosis in a magnetically levitated blood pump without the need for additional sensors or other equipment. In the proposed method, a sinusoidal current is applied to the electromagnets used for the magnetic bearing, resulting in vibration of the impeller. The phase difference between the current and displacement of the impeller increases with pump thrombosis. First, we describe the principle by which the pump thrombosis is detected. Pump thrombosis reduces the narrowest fluid gap in the pump and this gives rise to a change in the phase difference. Second, we report on experiments in which we changed the narrowest fluid gap using oriented polypropylene tape and showed that decreasing the narrowest fluid gap resulted in an increase in phase difference. For these experiments, the measurements were repeated three times for each condition. Third, we examine the relationship between the pump thrombosis and the phase difference evaluated by observations of the underside of the impeller when operating the pump with porcine blood. Since light was unable to penetrate the blood layer, the erythrocytes were removed for this observation. Only one observation was made. The results showed the phase difference rapidly increased at the same moment when the pump thrombosis was observed. This implies the proposed method has the potential to detect the early stages of pump thrombosis. Finally, in vitro experiments to detect thrombosis when using whole porcine blood in the pump were conducted. The experiment was carried out five times. To intentionally form a thrombus inside the pump, the activated clotting time was controlled to be less than 200 s. In every case, the phase difference increased by more than one degree after tens of minutes. Then, the pump was disassembled and a small amount of pump thrombosis was observed. We conclude that real-time diagnosis of pump thrombosis may be realized by measuring the phase difference without the need for additional sensors.

DOI： 10.1111/aor.13632

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Language：Japanese   Publisher：The Japan Society of Applied Electromagnetics and Mechanics  

The magnetic resonant wireless power transfer system with a function of human tracking has been proposed in order to supply the electrical energy to a power assist robot suit. A simple and fast algorithm using the gradient ascent to calculate optimal coil position based on the position and attitude of a receiver coil was developed. Simulation results showed that the optimal coil positions and attitudes of the transfer and repeater coils were calculated within 0.1 s. Even the receiver coil moved with a speed of 1 m/s, the algorithm could give the coil positions within the sufficient time to keep the high transfer efficiency. The simulated optimal coil position was compared with the experimentally measured optimal position and they showed good agreement each other.

DOI： 10.14243/jsaem.27.302

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

We propose an energy harvesting device driven by the contraction of an electrically-stimulated skeletal muscle that can be used as an alternative to batteries for implantable medical devices. In order to realize a durable generator, this device has a contactless plucking mechanism comprising parallel leaf springs and magnets, with which the generator can be driven without friction. By utilizing this mechanism, the generator can be driven not only in the contraction phase of the muscle, but also during relaxation. For the design we optimized the stiffness of the springs, the gap between the magnets, and the magnetic circuit in order to maximize the power generated. The power generated by a prototype in a benchtop experiment was 35.8 μW, which is sufficient to drive an implantable medical device. Furthermore, we evaluated the power generated in an ex-vivo experiment in which the gastrocnemius muscle of a toad weighing 193.4 g was electrically stimulated to drive the mechanism. In this experiment, 18.1 μW of power was generated from a skeletal muscle weighing only 3.5 g. It was also confirmed that the power generated exceeded the power required to electrically stimulate the skeletal muscle. The results showed the feasibility of an energy harvesting system utilizing the proposed mechanism.

DOI： 10.1299/jamdsm.2019jamdsm0068

DOI： 10.1299/jbse.22-00269_references_DOI_OzYGB6YcDESOXcyUNNQH973tDy7

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Mechanical circulatory support devices have been used clinically for patients with heart failure for over 10 years. However, thrombus formation inside blood pumps remains a risk to patient life, causing pump failure and contributing to neurological damage through embolization. In this article, we propose a method for preventing thrombus formation by applying vibrational excitation to the impeller. We evaluate the ability of this method to enhance the antithrombogenic properties of a magnetically levitated centrifugal blood pump and ensure that the impeller vibration does not cause undue hemolysis. First, 3 vibrational conditions were compared using an isolated pump without a mock circulation loop; the vibrational excitation frequencies and amplitudes for the impeller were set to (a) 0 Hz-0 μm, (b) 70 Hz-10 μm, and (c) 300 Hz-2.5 μm. The motor torque was measured to detect thrombus formation and obtain blood coagulation time by calculating the derivative of the torque. Upon thrombus detection, the pump was stopped and thrombi size were evaluated. The results showed an increase in the blood coagulation time and a decrease in the rate of thrombus formation in pumps with the impeller vibration. Second, an in vitro hemolysis test was performed for each vibrational condition to determine the effect of impeller vibration on hemolysis. The results revealed that there was no significant difference in hemolysis levels between each condition. Finally, the selected vibration based on the above test results and the non-vibration as control were compared to investigate antithrombogenic properties under the continuous flow condition. The blood coagulation time and thrombi size were investigated. As a result, vibrational excitation of the impeller at a frequency of 300 Hz and amplitude of 2.5 μm was found to significantly lengthen clotting time, decreasing the rate of pump thrombus compared to the non-vibration condition. We indicate the potential of impeller vibration as a novel mechanical antithrombogenic mechanism for rotary blood pumps.

DOI： 10.1111/aor.13541

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Mouthguard type sensors have been developed to monitor the healthcare-related information. In order to realize a battery-less sensor system, we propose a sheet form generator driven by occlusal force to supply electrical power for mouthguard type sensors. The proposed generator is made by stacking an electret and a dielectric elastomer. It converts mechanical energy applied by occlusion to electrical energy by electrostatic induction. In this study, the generator sheet was designed and its ability of power generation was evaluated experimentally. The prototype generator achieved 6.2 μW under the force equivalent to occlusal force. The generated power was 190 times as large as that of piezoelectric type. Although the achieved power is not sufficient to provide energy for mouthguard sensors so far, the output power will be improved by optimizing shape of dielectric elastomer and surface voltage of electret. The experimental results sufficiently support the possibility to realize the battery-less sensor system.

DOI： 10.14243/jsaem.27.188

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Ventricular assist devices assist in blood circulation and form a crucial component of artificial hearts. While it is important to measure parameters such as the flow rate, pressure head and viscosity of the blood, implanting additional devices to do such measurements is inadvisable. To this end, we demonstrate the adaptation of a ventricular assist device for the purpose of measuring blood viscosity. Such an approach eliminates the need for additional dedicated viscometers in artificial hearts. In the proposed method, the blood viscosity is measured by applying radial vibrational excitation to the impeller in a ventricular assist device using its magnetic levitation system. During the measurement, blood is exposed to a combination of a low shear rate (≈100/s) generated by the radial vibration of the impeller and a high shear rate (>10,000/s) generated by the impeller's rotation. The apparent viscosity of blood depends on the shear rate, so we determined which shear rate was the dominant one in the proposed method. The measurement results showed that the viscosity measured by the proposed method was in good agreement with the reference viscosity measured with a high shear rate. The mean absolute deviation in the measurements using the proposed method and those obtained using a concentric cylindrical viscometer at a high shear rate was 0.12 mPa s for four samples of porcine blood, with viscosities ranging from 2.32 to 2.75 mPa s.

DOI： 10.1177/0954411919838738

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Throwing an object by a powered robotic system is an effective way for object manipulation in long distance. The focus of the throwing is on the accuracy of the landing point with respect to model uncertainties or disturbances. A robust controller is often designed, however, the motion will be finished before the controller produces its effects because throwing is fast and highly dynamic. Moreover, the robot system sometimes has zero adjustment error in the initial position on its joint angle. This error cannot be overcome by a robust controller. So far, we have proposed a dynamic sensitivity analysis method of throwing for a feed-forward controlled manipulator. The sensitivity of the landing point with respect to zero adjustment error has been calculated, and robust throwing with small sensitivity has been designed. In this paper, the conventional method is applied to a feed-forward/back controlled manipulator in the real world, and evaluations are executed by using a prototyped three-link manipulator. The effectiveness of the proposed method is evaluated based on the sensitivity and variance of the landing point, and a robust throwing with small sensitivity is designed.

DOI： 10.1299/mej.17-00442

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DOI： 10.1016/j.sna.2016.10.027

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Implanted batteries and transcutaneous drive lines are used for powering active implantable medical devices (AIMDs) such as pacemakers and nerve stimulators. However, those devices cause physical burdens to patients due to surgery of the battery replacement and infections through the drive lines. Hence, we have proposed an implantable energy harvesting system (IEHS) using the contraction energy of electrically stimulated muscles. Previously, we fabricated an electromagnetic induction generator for the IEHS. However, the generator is large and complex because of the requirement of speed increaser. Therefore, in order to realize a smaller and simpler generator for the IEHS, we focused on electrostatic induction generators without any speed increaser using electret which may generate electricity at lower rotational speeds. Firstly, we evaluated electric charge on the electret sheets measuring the surface potential. Secondary, we measured output power of the electrostatic induction generator having several combinations of gaps and the number of poles of the electret sheets. Finally, the output power was compared with that of the electromagnetic induction generator.

DOI： 10.14243/jsaem.24.131

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DOI： 10.1063/1.4953653

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An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices.

DOI： 10.1177/0954411916638889

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Oil film bearings are applied for large rotational machineries owing to their large load capacity and damping effect. However, a swirling flow of the lubricant induces self-excitation at high rotational speed. The stability margin changes during many years due to the mechanical wear and fatigue. Thus, stability diagnosis of the rotor-oil film bearing systems is required. In this paper, we focus on the onset rotational speed of self-excitation as a stability index. Firstly, a 2-DOF rotor-oil film bearing model is constructed using the mode synthesis method and Bently/Muszynska model for oil film bearings. Then, an estimation method of the onset rotational speed using frequency responses measured at lower rotational speeds than the onset one is derived from the model. Finally, a test rig consisting of a rotor supported with two oil film bearings and a radial magnetic bearing is fabricated and frequency response functions with forward circular excitation are measured by utilizing the magnetic bearing. The experimental result shows that the predicted onset rotational speed using the frequency responses at 30, 40 and 50 rps is 60.4 rps, and the error between the estimated and measured onset rotational speeds is less than 4 rps (6%).

DOI： 10.1299/transjsme.15-00500

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DOI： 10.1109/LMAG.2015.2508004

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DOI： 10.1299/jamdsm.2015jamdsm0046

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Controlling the flow rate in an implantable rotary blood pump based on the physiological demand made by the body is important. Even though various methods to estimate the flow rate without using a flow meter have been proposed, no adequate method for measuring the blood viscosity, which is necessary for an accurate estimate of the flow rate, without using additional sensors or mechanisms in a noninvasive way, has yet been realized. We have developed a sensorless method for measuring viscosity in magnetically levitated rotary blood pumps, which requires no additional sensors or mechanisms. By applying vibrational excitation to the impeller using a magnetic bearing, we measured the viscosity of the working fluid by measuring the phase difference between the current in the magnetic bearing and the displacement of the impeller. The measured viscosity showed a high correlation (R(2)  > 0.992) with respect to a reference viscosity. The mean absolute deviation of the measured viscosity was 0.12 mPa·s for several working fluids with viscosities ranging from 1.18 to 5.12 mPa·s. The proposed sensorless measurement method has the possibility of being utilized for estimating flow rate.

DOI： 10.1111/aor.12440

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DOI： 10.18494/SAM.2015.1068

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DOI： 10.1016/j.precisioneng.2014.10.012

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In order to avoid the drive line infection of implantable devices and the surgical treatment for battery replacement, an intravascular micro turbine generator using blood flow, has been proposed and developed. The micro generator consisting of a micro turbine, a magnetic fluid (MF) seal, a stent, and an electrical generator is inserted by catheter into a descending aorta, which is able to reduce the invasiveness to patients. The experimental results using a prototype generator placed in a mock circuit loop showed that the resisting pressure of the MF seal was more than 25 kPa at 2,000 rpm and the generated power was 0.12 mW under a pulsatile flow condition.

DOI： 10.14243/jsaem.23.151

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

In the field of centrifugal blood pumps, contactless support of the impeller by a magnetic bearing has been identified as a promising method for reducing blood damage and to enhance durability. We developed a novel blood pump both with a two-degree-of-freedom radial controlled magnetic bearing and a contactless torque transmission mechanism placed in the outer side of a permanent magnet-free impeller. The proposed mechanism can realize not only a smooth secondary flow in the pump, but also a cost effective pump head. The prototype magnetic bearing and magnetic coupling succeeded in the stable levitation and contactless rotation of the impeller both in air and water. The pump can provide a flow rate of 5L/min against a head pressure of more than 350 mmHg. In order to simulate the ventricular assist condition, the prototype pump was connected to a mock systemic circulatory loop including a pulsatile pump. The dynamic stability of the impeller was experimentally verified when the pulsatile pressure was applied during the left ventricular assist.

DOI： 10.2493/jjspe.80.81

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DOI： 10.1177/0954411911422842

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A disposable magnetically levitated centrifugal blood pump, which aims to be used for from a few days to a few months, has been developed. An impeller is levitated and rotated without contact using a two-degree-of-freedom radial magnetic bearing and a magnetic coupling. Due to 'out-of-step' of the magnetic coupling caused by its insufficient transmittable torque, a previous prototype pump could not yield the required pressure-flow characteristics of 5 L/min against 106 kPa (800 mmHg). The magnetic coupling was redesigned in order to increase the transmittable torque. The stability of the impeller levitation against impact was evaluated through a base excitation test simulating animal experiment and practical use. Applying an impulse excitation of an acceleration of 200 m/s², the impeller could keep contactless levitation both in the controlled direction and in the passively supported directions. Finally, the animal experiments for one to two weeks showed that no damage and no thrombus formation were found in the pump heads.

DOI： 10.2493/jjspe.76.1064

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DOI： 10.1111/j.1525-1594.2010.01107.x

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DOI： 10.1111/j.1525-1594.2009.00957.x

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DOI： 10.1111/j.1525-1594.2009.00900.x

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DOI： 10.1111/j.1525-1594.2006.00332.x

DOI： 10.1111/j.1525-1594.2009.00817.x_references_DOI_FYcLOoBEqPCevFvk6XGahSAVS3l

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DOI： 10.5136/lifesupport.18.89

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DOI： 10.1111/j.1525-1594.2006.00229.x

DOI： 10.1177/0391398820984485_references_DOI_FhiFSA12TqMGZdroxiKpFy0WIdy

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper, summary (international conference)   Publisher：IEEE  

DOI： 10.1109/bmeicon64021.2024.10896336

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DOI： 10.1109/powermems63147.2024.10814518

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Plasma skimming in spiral groove bearings (SGBs) has the potential to reduce hemolysis by guiding the red blood cells to escape from the narrow ridge gap with high shear stress force, to the larger groove gap. In our previous study, we designed an optimal SGB-PS that aims to improve plasma skimming inside the bearing gaps and verified its effectiveness under whole blood conditions up to 40% hematocrit level. This study extends our work by evaluating the load-carrying capacity of the optimized SGB design. We first analyzed the load-carrying capacity numerically by calculating the hydrodynamic force based on the Reynolds equation. Then we designed and manufactured an experimental device to measure the generated hydrodynamic force under comparable conditions. Our results indicate that the hydrodynamic force generated by the SGB-PS meets the requirements for our hydrodynamically levitated rotary blood pump and aligns well with our numerical analysis. This research contributes to improving the performance of the SGB for hemolysis resistance in hydrodynamically levitated rotary blood pumps.

DOI： 10.1109/embc53108.2024.10781874

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Wireless power transfer via magnetic resonant coupling can be used to supply power to a mobile robot. However, when the robot moves or its power consumption fluctuates, its input impedance varies that leads to an increase in power reflection. Therefore, we propose the use of multiple identical driver coils on the transmitter side to match the input impedance. The input impedance is matched and power reflection is eliminated by switching driver coils, i.e., regulating the coupling coefficient between the driver and the transmitter. In addition, the winding number of the receiver coil can be switched to facilitate the design of the driver coil. The experimental results showed the proposed system could accelerate battery charging time and extend the robot's operating time with automated impedance matching.

DOI： 10.1299/jsmermd.2023.2p1-g17

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Language：Japanese   Publisher：公益社団法人 精密工学会  

本研究では人工心臓に用いる磁気浮上機構を，血栓の検出および予防システムとして利用する．具体的には，血液吐出用インペラを円軌道状に強制変位加振する．このとき，血栓形成時のインペラダイナミクスの変化を捉え，血栓検出センサへ応用する．また，この加振により，血栓形成初期段階の血液成分付着を阻止し，血栓を予防する．この制御の効果を検証するため，ブタ血液を充填した模擬循環回路を用い，実証した．

DOI： 10.11522/pscjspe.2023s.0_283

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骨格筋と人工骨格からなるバイオアクチュエータは，自己成長，自己修復等の特徴を有する。本研究ではバイオアクチュエータの工学的応用を目指し，筋疲労を考慮した筋収縮モデルの構築，および骨格筋のモデルベース設計法を提案する。実験ではカエル腓腹筋の収縮応答を測定し，骨格筋の長さ等とモデルパラメータの関係を実験的に求め，所望の仕様を満たす骨格筋を設計し，カエルの筋肉で妥当性を検証した。

DOI： 10.11522/pscjspe.2023s.0_507

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We propose a self-powered stretchable artificial skin that can detect the contact position. The proposed skin is made from a lamination of an elastomer, an electret, and two electrodes. An electret is a dielectric material that can retain an electric charge on its surface. When a compressive force is applied, the positive charge induced in the electrodes is transferred through the shunt resistor connected to the two electrodes, causing a voltage drop that is used in contact detection. The internal resistance of the elastomer-side electrode is divided according to the compression position, resulting in a change of a differential voltage drop. The contact position is detected using the change. Experimental results confirmed that contact position detection with an estimation error of less than about 8 mm is possible.

DOI： 10.1299/jsmermd.2023.1p1-h13

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Wireless power transfer via magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies and causes power reflection. Therefore, we propose the use of multiple identical driver coils on the transmitter side in order to match the input impedance. The input impedance is matched and power reflection is eliminated by switching driver coils, i.e., regulating the coupling coefficient between the driver and the transmitter. In addition, the winding number of the receiver coil can be changed to relax the design condition of the drive coil. The experimental results showed the input impedance was well-matched under a wide range of distances and load resistances. Therefore, the proposed system was expected to solve the power reflection issues in mobile robots automatically.

DOI： 10.1109/wpw54272.2022.9901340

DOI： 10.14243/jsaem.31.90_references_DOI_L7pundJ3wzXns0nv22NE06H0ZzJ

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Biohybrid actuators consisting of skeletal muscle and artificial lattice possess unique features such as self-growth and self-repair functions. As a first step in developing a model-based design for biohybrid actuators, we used the existing muscle contraction model to propose a design method that can achieve appropriate performance for muscle specification. Utilizing the actual skeletal muscle of the toads, muscle contraction force under multiple square waves with different frequencies and amplitudes are used to determine the model parameters by fitting them to the simulated forces. Based on the results, the relationship between the muscle specification and the model parameters is obtained, and we successfully designed muscle specification required to generate specific contraction force based on this model.

DOI： 10.1299/jsmermd.2022.2p2-n01

DOI： 10.1299/jbse.24-00017_references_DOI_Iu1XAaqcsDvKrv1AZirDTnFWEg6

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本研究では人工心臓用の磁気浮上アクチュエータを単なる浮上機構としてだけでなく，患者の拍動や疾患状態をセンシング可能なスマートアクチュエータとして利用する．具体的には磁気浮上系に構成した外乱オブザーバによりインペラに作用する流体力を推定し，リアルタイムで疾患心臓の拍動を推定可能とした．さらに，繰返し制御器を用いたモータの心拍同期制御系を設計し，推定した拍動に同期する流量制御を実現した．

DOI： 10.11522/pscjspe.2022s.0_676

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人工心臓用インペラの支持に動圧軸受や磁気軸受が利用されるが，狭い流体隙間での血液損傷や，アクティブ制御システムの故障が懸念される．本研究では，推力と磁力を併用することで500 µm以上の流体隙間を有し，かつ完全パッシブ浮上可能な軸流血液ポンプを開発する．数値流体力学解析と磁場解析により回転以外の5自由度が正剛性となる浮上機構を設計し，実験により10,000 rpm，1.5 L/minにおいて軸方向のパッシブ浮上を示した．

DOI： 10.11522/pscjspe.2022s.0_798

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Publisher：The Korean Society of Neurogastroenterology and Motility  

Chronic constipation and lifestyle factors can affect sleep quality. We evaluated the relationship between chronic constipation and sleep in the Japanese population.This cross-sectional internet-based survey included 3000 subjects with constipation, classified according to sleep status (good/poor). Primary endpoints were Bristol stool form scale (BSFS) score and correlations between sleep disorder criteria of the Pittsburgh Sleep Quality Index (PSQI) and sleep status (good/poor sleep). Secondary endpoints included correlations between quality of life (QOL) and mood, medical, lifestyle, and sleep factors.The proportion of participants with BSFS category 4 (normal stool) was significantly higher in the good sleep group (Subjects with constipation and poor sleep experienced severe symptoms and had poor QOL. These data support the need for a multifocal treatment approach, including lifestyle advice and pharmacotherapy.

DOI： 10.5056/jnm20135

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One of the challenges of blood pumps that are being used for a long time is the synchronous control of flow rate with a natural heartbeat and the control of blood coagulation. To realize these control systems, it is usually necessary to use additional sensors in the blood pump system. This is, however, difficult in the case of implantable pumps due to the complexity and increasing size of the system. Hence, we have proposed a method in which a magnetic bearing is applied not only as a mechanism to support the impeller but also used as a sensor to measure biological information in real time, thereby achieving the heart rate synchronization control and the thrombosis detection and prevention in the blood pump. We conducted in vitro experiments with a mock circulatory loop to evaluate the proposed methods.

DOI： 10.1299/jsmedmc.2021.542

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In order to develop a new kind of actuator made of physiological tissue muscle, the initial task as the purpose of this study is to design the minimum muscle weight required to generate specific contractile force. In this study, gastrocnemius muscle of toad was subjected to external electrical stimulation signal. Utilizing the muscle contraction model, with electrical stimulation signal as input, it shows that muscle contraction can be simulated by adjusting specific parameter of the model. Initially, the relationship between muscle contraction model and muscle weight was revealed by experimentally stimulating muscles of different sizes under several kinds of stimulus conditions. Then, we successfully designed muscle weight required to get the contractile force expected based on the muscle contraction model.

DOI： 10.1299/jsmermd.2021.1p3-j04

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Wireless power transfer via magnetic resonant coupling makes it possible to supply electricity for a target device which is within a few meters from the transmitter coil. However, when the target device moves and works, power reflection occurs due to the variation of input impedance. Therefore, we suggested the method using a driver coil on the transmitter side to control input impedance. Regulating coupling coefficient between the driver coil and the transmitter one, input impedance is to be matched, and the reflection is eliminated. In the experiment, the transmitting efficiency showed good agreement with the calculated value and input impedance was able to be matched under transition of distance and load resistance. In conclusion, it was shown that the proposed system could solve the problem of power reflection in a mobile robot.

DOI： 10.1299/jsmermd.2021.1p3-g04

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Developing real-time detection of thrombus formation in extracorporeal membrane oxygenations would be efficient to prevent thrombosis and bleeding complication and evaluate device antithrombogenicity. This study showed a novel thrombus detection method in an oxygenator using indocyanine green (ICG) fluorescence imaging. To verify the efficiency of the method, in vitro experiments and animal experiments on pigs were conducted. Compared to eye observation, ICG fluorescence imaging revealed thrombi in the oxygenator as black areas in detail. Those areas were very similar to thrombi observed on the oxygenator after rinsing with saline. Although this method could detect only thrombi on surfaces of the oxygenator, the observations of the decomposed oxygenator showed there were little thrombi in the hollow fiber bundles. Therefore, ICG fluorescence imaging is feasible to detect thrombus formation in an oxygenator in real-time.

DOI： 10.11239/jsmbe.annual59.579

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The purpose of this research was to propose synchronous control of the pump flow rate with the natural heart by estimating heartbeat and estimated a pump flow rate without using additional sensors. In this study, we have developed a disturbance observer to estimate heartbeat for estimating the radial thrust, which is the force generating on the impeller by the blood flow in the blood pump. The pump flow rate was also estimated from the radial thrust by experimentally determining the relationship between the pump flow rate and the radial thrust. The validation test was conducted using a simple mock circulation loop, and the heartbeat and the pump flow rate were successfully estimated by the proposed method. Our results concluded that using the heartbeat and pump flow rate estimation system proposed in this study enabled synchronous control with simulated natural heart in a simple mock circulation loop.

DOI： 10.14243/jsaem.29.72

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DOI： 10.11522/pscjspe.2021a.0_279

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We propose a flexible artificial skin with a tactile function that requires no external power supply. The proposed skin is made from a lamination of an electret, an elastomer and two electrodes. The electret is a material in which electric charges are stored semi-permanently. In this study, an electret with a thickness of 15 μm was made by applying amorphous fluororesin on a 10 μm thick copper electrode. After that, an elastomer containing carbon black was applied to the opposite electrode with a thickness of 1.0 mm, and these were laminated to fabricated an artificial skin of about 1.1 mm. The results of experiments in which the pressure was applied to the prototype skin showed that the detected, voltage was 16 V, which was sufficient to use as a sensor for detecting the contact. Furthermore, a principle to detect the position of contact point is proposed and verified in simulation. In the future work, experiments to estimate the contact point will be carried out.

DOI： 10.1299/jsmermd.2021.1p1-m12

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Language：Japanese   Publisher：Japan Gastroenterological Endoscopy Society Kanto Chapter  

A 62-year-old male was admitted to hospital the limb sensation and a weakness in the main complain. He had an emergency upper gastrointestinal endoscopy because a result of his blood test was severe anemia, Hb 4.9 ml/dL.

The endoscopy showed a hemorrhagic gastric ulcer with a huge exposed vessel.

On treatment with IVR, it was difficult for us to insert a catheter in his vessel because his vessels have abnormal running vessels. Therefore, we decided to insert an intra-aortic balloon occlusion (IABO) catheter on treatment with endoscopy. The IABO helped to control the ulcer bleeding and made an easier for us to complete an endoscopic hemostasis with coagulation.

Gradually over a period of two months, the ulcer was healed to normal mucosa. Such as this case, it is suggested that IABO is able to be completed an endoscopic hemostasis for a case that be predicted difficulty to hemostasis.

DOI： 10.11641/pde.97.1_66

DOI： 10.7888/juoeh.43.363_references_DOI_ULo7m6YEEb702jil3LHVRFGsztG

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Other Link： https://search.jamas.or.jp/link/ui/2021104126

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

We propose an artificial skin with a flexible thin film and a tactile function that requires no external power supply. The proposed skin is made from a lamination of an electret, an elastomer and two electrodes. The electret is a material in which electric charges are stored semi-permanently. In this study, an electret with a thickness of 15µm was made by corona discharge after dropping amorphous fluororesin on a 10µm thick copper electrode. After that, an elastomer was applied to the opposite electrode with a thickness of 20 µm. These were laminated each other to produce an artificial skin. The results of experiments in which the pressure was applied to the prototype skin showed that the detected, voltage was 2V, which was sufficient to used as a sensor for detecting the contact.

DOI： 10.1299/jsmeiip.2020.2a04

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Language：English   Publisher：The Japan Society of Applied Electromagnetics and Mechanics  

The magnetic resonant wireless power transfer (WPT) system has been applied to electrically-driven mobile systems. Although the magnetic resonant WPT system is relatively robust against the misalignment between a transfer (Tx) coil and receiver (Rx) coil, it is difficult to keep the energy transfer when the relative position of the coils changes significantly. This will be a technical issue in the WPT for wearable and implantable devices. To solve this, WPT system with a function of human tracking has been proposed. A simple and fast algorithm using the gradient ascent to calculate optimal coil position based on the position and attitude of a Rx coil was developed. In this paper, basic principle of this system and evaluation results are introduced.

DOI： 10.14243/jsaem.28.271

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

We propose an artificial skin with a flexible thin film and a tactile function that requires no external power supply. The proposed skin is made from a lamination of an electret, an elastomer and two electrodes. The electret is a material in which electric charges are stored semi-permanently. In this study, an electret with a thickness of 15 μm was made by applying amorphous fluororesin on a 10 μm thick copper electrode. After that, an elastomer containing carbon black was applyed to the opposite electrode with a thickness of 250 μm, and these were overlaid to produce an artificial skin of about 300 μm. These were laminated each other to produce an artificial skin. The results of experiments in which the pressure was applied to the prototype skin showed that the detected, voltage was 0.5V, which was sufficient to used as a sensor for detecting the contact.

DOI： 10.1299/jsmermd.2020.2a1-p09

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Energy harvesting from human motion is expected to the energy source for wearable devices. Although the energy density of human motion is high, the frequency of it is a few Hz, which does not match the conventional energy harvester. Due to this, the size of harvester tends to become large in order to get high output. This paper presents an electrostatic induction energy harvester which can generate high power at low frequency in order to power the mouthguard type sensor. To embed into the mouthguard type sensor, the total thickness of the harvester should be less than 0.2 mm to reduce the discomfort. Furthermore, the final goal of power generated of the harvester was set to a few tens of μW. The proposed harvester consists of electrets that can hold a quasipermanent charge on its surface, dielectric elastomers and electrodes. The mechanical energy applied by the biting force is converted to electrical energy by electrostatic induction. The parametric study of the harvester based on the equivalent circuit model was conducted to maximize the power generated. According to the calculation results, the harvester can achieve 22.7 μW with a load resistance of 570 MΩ, which met the requirements for the mouthguard type sensors. The fabrication and evaluation of the harvester based on the calculation results will be conducted in the future work.

DOI： 10.1299/jsmeintmovic.2020.15.10082

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Publisher：Science Impact, Ltd.  

<jats:p>Heart disease is the leading cause of death in men and women around the world and it is a significant problem that requires remedy. Heart failure is where the heart is not pumping blood around the body as effectively as it should. Importantly, heart failure does not mean that the heart
has stopped working, but it does require support in order to get it working better. Over the past few decades, there have been many innovations to help address the problems with heart failure, including developing ventricular assist devices (VADs). A VAD is a mechanical pump that is placed
inside the body to support heart function and blood flow in heart patients. It works by taking blood from a lower chamber in the heart and pumping it to the body and vital organs, in the same way that a healthy heart would. Dr Wataru Hijikata is an expert in mechanical engineering and technology
with a focus on healthcare outcomes. He explains that the first generation of VADs was a pulsatile flow type, but because of the complicated mechanical structure, the size of them was large and they had low durability. He notes that the second generation VAD was a continuous flow type. Because
the blood flow was generated by the rotation of an impeller, the mechanical structure was simple and the size was small. However, the bearings to support the rotating impeller led to low durability. 'Third generation VADs are continuous flow types with contactless support of the impeller by
magnetic bearing or hydrodynamic bearings,' Hijikata outlines. Owing to the contactless support technology, the durability of VADs has been enhanced and the size of the device is small. 'However, while there has been significant progress over the years, VADs are still far from perfect and
there is much room for improvement,' he concludes. With that in mind, a team of researchers based at the Department of Mechanical Engineering in the Tokyo Institute of Technology, Japan, is investigating a means of improving VADs.</jats:p>

DOI： 10.21820/23987073.2019.10.70

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H04909/

Publisher：Springer Science and Business Media LLC  

In Japan, the prevalence of constipation-predominant irritable bowel syndrome (IBS-C) and functional constipation (FC) diagnosed by the Rome III criteria is unclear, as are the demographic profile, quality of life (QOL), and habits of persons with IBS-C or FC.We performed an internet survey of constipation. After extracting 3000 persons fitting the composition of the general Japanese population, we investigated demographic factors, lifestyle, defecation, and laxatives. IBS-C and FC were diagnosed by Rome III criteria. Respondents also completed the Japanese IBS severity index (IBS-SI-J), Japanese IBS QOL scale (IBS-QOL-J), SF-8, Hospital Anxiety and Depression Scale (HADS), and Japanese Health Practice Index (JHPI).There were 262 respondents with FC (8.73%) [73 men and 189 women; mean age: 49.8 ± 13.1 years; mean body mass index (BMI): 21.0 ± 3.3 g/mIn Japan, among the population of under 70 years old, the prevalence of IBS-C and FC (Rome III criteria) was 4.97% and 8.76%, respectively. IBS-C caused more severe symptoms than FC, resulting in impairment of QOL.

DOI： 10.1007/s00535-019-01611-8

DOI： 10.3164/jcbn.19-118_references_DOI_3Qs0sj3JMTlYBZhhgQJHSbl67ss

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Other Link： http://link.springer.com/article/10.1007/s00535-019-01611-8/fulltext.html

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DOI： 10.1109/EMBC.2019.8856414

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Language：English   Publisher：IEEE  

Mouthguard type sensors have been developed to monitor the healthcare-related information, which is expected to be used for pre-illness and preventive medicine. However, a method for supplying the power to these sensors is still an issue to be solved. In this paper, we propose an electrostatic oral cavity generator driven by occlusal force to supply the power for mouthguard type sensors. The proposed generator is a sheet form and consists of the lamination of the electret, dielectric elastomer and copper electrode. In this paper, we estimated the power generation with a piezoelectric generator and the proposed electrostatic generator. Then, the generators were designed and fabricated. The generated power of the prototype electrostatic generator was 18.0 μW. It was about 560 times larger than that of a piezoelectric generator with the area equivalent to four pairs of molars. Although the generated power was still smaller than the required power to drive the mouthguard sensor, we considered they can be comparable with each other by optimizing the design parameters of the generator.

DOI： 10.1109/EMBC.2019.8856933

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Language：English   Publisher：IEEE  

DOI： 10.1109/EMBC.2019.8857735

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We have developed a magnetic levitation system with an intelligent function. In the system, sinusoidal current is intentionally superposed to electromagnets and the levitating rotor is vibrated. By measuring the phase difference between the displacement of the rotor and current in the electromagnets, the change of the bearing gap and viscosity of working fluid can be detected. The proposed function is applied to the detection of thrombus in a magnetically levitated artificial heart. The experimental results with the porcine blood showed the phase difference increased to two degrees when the thrombus was generated in the pump. Then, the function was further developed for preventing the pump thrombus. By intentionally levitating the impeller with the frequency of 300 Hz and the amplitudes of 2.5 μm, the pump thrombus generated on the impeller was decreased compared with the thrombus without vibration.

DOI： 10.1299/jsmemovic.2019.16.b302

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Mouthguard type sensors have been developed to monitor the biometric information. In order to realize battery-less intraoral sensors, we propose an intraoral electrostatic energy harvester driven by occlusal force. The proposed energy harvester consists of lamination of the electrodes, electret and dielectric elastomer. The energy harvester converts mechanical energy applied by occlusal force into electrical energy by electrostatic induction. In this study, we measured the relationship between the thickness of the electret and the power generation. The experimental results showed the electret of 10 μm thickness was suitable for the proposed energy harvester and it achieved 18.0 μW power generation with the area of 400 mm² under the force equivalent to occlusal force.

DOI： 10.1299/jsmeiip.2019.1d07

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Thrombus is one of the major problems in ventricular assist devices (VADs). However, method for detecting thrombus in early stage has not been established yet. In this study, we propose an intelligent function that the VAD itself can detect thrombus automatically and alert it to medical staffs. In the proposed method, thrombus formation inside a blood pump is detected by monitoring blood viscosity. This viscosity measurement is performed by using magnetic levitation system for the impeller. Hence, it can be implemented without any additional sensors or mechanisms in principle. For verification of the method, at first, we visualized inside of the pump during thrombus formation with measuring blood viscosity by using erythrocytes removed porcine blood. The result showed that the viscosity of the blood increased as blood coagulation progressed. Then, we conducted in vitro principle verification experiments with three different whole porcine blood. In all experiments, the measured blood viscosity increased and small thrombus was observed inside the pump. From these results, we confirmed that the proposed method has a possibility to detect and predict the thrombus in early stage.

DOI： 10.1109/EMBC.2018.8513137

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Language：Japanese   Publisher：The Japanese Society of Internal Medicine  

DOI： 10.2169/naika.107.1357

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I029166220

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

For a robot that works in shared space with human, collision avoidance control or impact absorption control will be required for the safety issues. Compliance control will be an effective way for impact absorption without any additional sensors, however, it sometimes yields second collision because the robot is controlled to come back to the equilibrium point. To avoid the recollision, the robot has to change its position i.e. it has to be controlled to another equilibrium. In this paper, we propose a controller design method that stabilizes the robot to equilibrium manifold. A virtual potential is defined so that it has stationary region on the specified equilibrium manifold, and a controller is designed based on the gradient of the potential. The proposed method is evaluated through simulations and experiments using prototyped double inverted pendulum system.

DOI： 10.1299/jsmermd.2018.2a2-e15

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Throwing an object by powered robot system is an effective way for object manipulation in long distance. The focus of the throwing is on the accuracy of the landing point with respect to model uncertainties or disturbances. Moreover, the robot system sometimes has zero adjustment error in the initial position on its joint angle. So far, we have proposed a sensitivity analysis method of throwing with a feed-forward/back controlled manipulator. The sensitivity of the landing point with respect to zero adjustment error has been calculated, and the robust throwing with small sensitivity has been designed. In this paper we design robust controller with small sensitivity by optimizing feed-back gain instead of robust throwing motion, and evaluate the effectiveness of the proposed method using a prototyped three-link manipulator.

DOI： 10.1299/jsmermd.2018.2p2-e11

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DOI： 10.1109/EMBC.2018.8513105

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DOI： 10.1109/WPT.2018.8639256

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Hepatitis C virus (HCV), dengue virus (DENV) and Japanese encephalitis virus (JEV) belong to the family Flaviviridae. Their viral particles have the envelope composed of viral proteins and a lipid bilayer acquired from budding through the endoplasmic reticulum (ER). The phospholipid content of the ER membrane differs from that of the plasma membrane (PM). The phospholipase A(2) (PLA(2)) superfamily consists of a large number of members that specifically catalyse the hydrolysis of phospholipids at a particular position. Here we show that the CM-II isoform of secreted PLA(2) obtained from Naja mossambica mossambica snake venom (CM-II-sPLA(2)) possesses potent virucidal (neutralising) activity against HCV, DENV and JEV, with 50% inhibitory concentrations (IC50) of 0.036, 0.31 and 1.34 ng/ ml, respectively. In contrast, the IC50 values of CM-II-sPLA(2) against viruses that bud through the PM (Sindbis virus, influenza virus and Sendai virus) or trans-Golgi network (TGN) (herpes simplex virus) were > 10,000 ng/ml. Moreover, the 50% cytotoxic (CC50) and haemolytic (HC50) concentrations of CMII- sPLA(2) were > 10,000 ng/ml, implying that CM-II-sPLA(2) did not significantly damage the PM. These results suggest that CM-II-sPLA(2) and its derivatives are good candidates for the development of broadspectrum antiviral drugs that target viral envelope lipid bilayers derived from the ER membrane.

DOI： 10.1038/s41598-017-16130-w

DOI： 10.1016/j.toxicon.2020.12.007_references_DOI_GswaWZLQkOaME1nNCIvQj3wD3Mb

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Other Link： https://www.nature.com/articles/s41598-017-16130-w

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Publisher：Trans Tech Publications, Ltd.  

<jats:p>Proton beam writing was carried out into high purity semi-insulating 4H-SiC bulk substrates. Luminescent defects created in the SiC by proton beam writing using 1.7 MeV-proton micro beams were investigated at room temperature using confocal laser scanning microscope. As a result, photoluminescence peak around 900 nm associated with silicon vacancy was observed for the irradiated SiC without post implantation process such as annealing. The overall depth profile of photon counts detected from irradiated areas is in good agreement with simulated vacancy depth profile. This suggests that silicon vacancy can be applied to ion tracking detector. In addition, since silicon vacancy is known as single photon source of which spins can be controlled at RT, PBW is expected to be a useful tool to fabricate spin qubits.</jats:p>

DOI： 10.4028/www.scientific.net/msf.897.233

DOI： 10.1088/1361-6463/aad0ec_references_DOI_SMgcS7E0tdWAszyxFQufHPiznnJ

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15H03967/

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>The results of conventional researches have concluded that a human motion is generated by torque change minimization algorithm. It requires information of both initial and final position (Point-to-point control), while human motion sometimes does not have information of the final position in the real world. In this paper, we propose an online torque change minimization algorithm. Human motions are measured by a motion capture system, and it is shown that human motion has small torque change. The proposed method is applied to the same motion and the effectiveness of the proposed method is evaluated. Finally, the proposed method is also applied to experiments of a two-link manipulator.</p>

DOI： 10.1299/jsmermd.2017.1A1-N11

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<p>Free-throw in basketball is extremely dynamic and sensitive to the error of the joint angle through the motion. The purpose of this research is to design a trajectory which is robust against the initial error of the joints using inverse dynamics analysis and sensitivity analysis of motion capture data of free-throw. For those analyses, the dominant joint angle for free-throw is identified. The free-throw data of some participants are acquired, and they are evaluated and classified as novice or expert. The sensitivity of the experts shows small value comparing novice one, and a trajectory which has lower sensitivity is designed for the novice.</p>

DOI： 10.1299/jsmermd.2017.2A2-D01

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<p>Throwing an object by a powered robot system is an effective way for object manipulation in long distance. The focus of the throwing is on the accuracy of the landing point with respect to model uncertainties or disturbances. So far, we have proposed a sensitivity analysis method of throwing with a feed-forward controlled manipulator, while feed-forward/back controlled one is considered in this paper. The dynamic sensitivity analysis method is developed based on the conventional method and its evaluation is executed by using a prototyped three-link manipulator. The effectiveness of the proposed method is evaluated and a robust throwing with low sensitivity is obtained that realizes small variance of the landing point.</p>

DOI： 10.1299/jsmermd.2017.1P1-H07

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DOI： 10.1299/jsmekanto.2017.23.1601

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DOI： 10.1299/jsmekanto.2017.23.1511

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A conventional power supply method using a drive line for a ventricular assist device causes infection diseases, which decreases patient&rsquo;s quality of life and survival rate. A possible solution is to use a transcutaneous energy transmission system utilizing electromagnetic induction. However, it is necessary for the coil to be located on the body surface accurately because of short transmission distance. In order to avoid infection diseases as well as increase the transmission distance, we proposed the new system utilizing magnetic resonant coupling that embedded flexible coils into clothes to transfer energy. In this paper, we evaluated the influence of the electric characteristics of the human body on the transmission efficiency by using both phantom and pork. The measured transmission efficiency with a gap of 30 mm was 67 % in phantom and 70 % in pork while that in air was 80 %.

DOI： 10.1299/jsmeiip.2017.F-04

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DOI： 10.1109/WPT.2017.7953865

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Language：Japanese   Publisher：府中町 (広島県) : マツダ財団  

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We proposed an active in vivo power generation system using electrical muscle stimulation as an alternative to an implanted battery and a-transcutaneous drive line. In this system, skeletal muscle contraction generated by applying electrical stimulation was used to drive a power generator. In this paper, an electromagnetic induction type one was designed to be compact, durable and efficient. The muscle contraction is transmitted to an oscillator supported by parallel leaf springs through a non-contact clutch mechanism using magnetic force. The experimental electric power generation was 20.9 μW, and the energy efficiency was 24.7%.

DOI： 10.1299/jsmermd.2016.1a1-02a6

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A sensorless noninvasive method for measuring blood viscosity has been developed for a magnetically-levitated centrifugal blood pump. The blood viscosity can be calculated from the measured phase difference between the input current to the magnetic bearing and the impeller displacement. The experimental results using porcine blood, which has a non-Newtonian property, showed the difference between the viscosity measured by a cylinder viscometer and one by the magnetic bearing was 0.3 mPa・s. In the range of 0.5 to 4.5 L/min, the variation of the measured viscosity was less than 0.2 mPa・s. The results indicate the proposed method can be applied to measure the blood viscosity for clinical use.

DOI： 10.1299/jsmeiip.2016.f-1-1

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2016.1.0_3548

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identifier:oai:t2r2.star.titech.ac.jp:50303288

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DOI： 10.1109/MEMSYS.2016.7421708

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To realize a lens drive actuator in mobile camera utilizing MEMS technology, micro-pitch and multi-pole magnetization of a sintered Nd-Fe-B magnet of 500 μm in thickness was discussed in this paper. First, the Nd-Fe-B magnet was bonded on a glass substrate using polyimide adhesive to buffer the thermal stress due to the difference of their linear expansion coefficients. Secondly, some slits were processed by a dicing at an interval of 650 μm. Then, each uniformly-magnetized and divided magnet part was alternately heated by a laser beam and each heated part was reversely magnetized by the leakage flux generated from both non-heated adjacent magnets. The micro-pitch and multi-pole Nd-Fe-B magnet generated the magnetic field of 0.48 T (p-p) at a distance of 100 μm from the surface, which is about 90% of that of simulated one.

DOI： 10.1299/jsmemnm.2015.7._29pm3-pn-_1

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In the rotor systems having oil film bearings and/or fluid seals, there is a possibility of fluid-induced vibration such as oil whip and oil whirl at high rotational speed. The stability analysis methods of the rotor systems are necessary, not only in the design phase but also under operation. In this study, we propose an approximate stability analysis method by utilizing the fluid force model developed by Bently and Muszynska and experimentally excited rotor responses at a low rotational speed. The proposed method enables the prediction of the onset of self-excitation. In order to evaluate the proposed method, the Hardware-In-the-Loop (HIL) simulator, which can simulates rotor vibration in real time, was constructed. From the simulation results, it became clear that the self-excitation was precisely estimated by the proposed stability analysis.

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In order to avoid infections caused by a percutaneous power supply cable for an implantable artificial heart, we propose a wireless power transmission system utilizing a magnetic resonant coupling technology, which can transmit electric power with wider gap than that in an electromagnetic induction technology. In order to compensate for decreasing the transmission efficiency due to the relative movement between a transmission coil and a receiver coil, coupling coefficient between the coils is enhanced by controlling attitude of the transmission coil according to the position and attitude of the receiver coil. In this study, effect of enhancing the transmission efficiency owing to both controlling the attitude of the transmission coil and matching the impedance was evaluated. Moreover, a motion capture Kinect is used for measuring the position and attitude of a patient implanting the receiver coil. The measurement accuracy of the Kinect was evaluated.

DOI： 10.1299/jsmermd.2015._1a1-d06_1

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As a method for power supply, we proposed an active in vivo power generation system using an electrical muscle stimulation technology as an alternative to an implantation of batteries and a wireless power transmission. In this system, contractile force generated by applying electrical stimulation to skeletal muscle was used as an energy source. In this paper, based on the results of muscle contraction characteristics by electrical stimulation, an electromagnetic induction type power generation mechanism was designed and fabricated. The power generation performance of the proposed generator was evaluated using the gastrocnemius muscle of a toad and the net power generated in the experiment was 112μW.

DOI： 10.1299/jsmermd.2015._1p1-f07_1

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In order to realize high-frequency and multi- dimensional laser beam focus positioning during laser beam cutting, a maglev 3-DOF lens driving actuator is developed. The objective of this paper is the design and fabrication of a compact maglev lens driving actuator which can drive the lens in both the axial and radial directions, and can be accommodated in the laser head of a conventional laser cutting machine.

DOI： 10.1299/jsmemipe.2015._MoP-40-1_

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DOI： 10.18494/sam.2015.1068

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In order to supply electricity to medical implantable devices, we propose an in vivo power generation system using an electrical muscle stimulation technology as an alternative to a percutaneous power supply and an implantation of batteries. To choose an effective power generation method using contraction of a part of the muscle, we investigated properties of the muscular contraction resulting from the electrical stimulation. Using the gastrocnemius muscle of a toad, we measured the muscular tension in the isometric contraction and the amount of shrinkage in the isotonic contraction. As a result of each measurement, the maximal tension of 1.1 N and the maximal distance of 3.2 mm were measured, respectively. It was concluded that the application of the piezoelectric generation was unsuitable because the isometric contraction had a long period. Therefor it suggested that the electromagnetic induction type that utilizing shortening of the muscle was desirable for a generator of the proposed system. Future works include optimization of the electrical stimulation signal considering muscle fatigue, investigation of the muscle contraction properties under the various load, and design of the power generation mechanism.

DOI： 10.1299/jsmemecj.2014._j2410102-

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

DOI： 10.11522/pscjspe.2014a.0_681

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DOI： 10.11522/pscjspe.2014a.0_133

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

DOI： 10.11522/pscjspe.2014a.0_679

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Language：Japanese  

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Publisher：Wiley  

<jats:sec><jats:label /><jats:p>We have studied the temperature dependence of optical transitions in dilute GaAsN alloys using photoreflectance (PR). A delocalized‐state transition is clearly observed in PR spectra while several localized‐state emission lines due to isoelectronic centers appear in photoluminescence spectra. The energy of optical transitions observed in PR spectra is in agreement with the excitonic transition energy in photoluminescence excitation spectra, clearly showing that the optical transitions in PR spectra are excitonic transitions. We analyzed the temperature dependence of the excitonic transition energies using the Bose–Einstein statistical expression, and found that even dilute alloys follow the same trend as GaAsN alloys with higher nitrogen concentrations. We discuss the coexistence of localized and delocalized states in dilute GaAsN alloys in terms of the random distribution of N atoms.</jats:p></jats:sec>

DOI： 10.1002/pssa.201300462

DOI： 10.1002/crat.202000143_references_DOI_M52BqHSFOdzDrBQgtQb6E5Yd9Hq

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-24360004/

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A sensorless flow rate measurement has been proposed to control a flow rate in a magnetically levitated centrifugal blood pump without any flow sensor. The proposed algorithm consists of a linear function of the flow rate and the ratio of rotational torque to rotational speed of the impeller. In the range between 0 and 10 L/min with a working fluid of water, the error of the estimated flow rate using directly measured torque was less than 0.51 L/min, which was about a half of the equivalent value using the torque estimated from motor power consumption. Using several working fluids whose viscosity ranged from 0.75 to 3.29 mPa・s, the viscosity was estimated with the error of less than 0.16 mPa・s, from the directly measured torque when the outlet was clamped. Estimated flow rate, compensated by the estimated viscosity, showed the error of less than 0.77 L/min in the range of up to 10 L/min.

DOI： 10.1299/jsmeiip.2014._f-2-1-1_

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Publisher：American Association for the Advancement of Science (AAAS)  

<jats:title>Soft, Selective CO Sorption</jats:title>
<jats:p>
Many industrial processes produce CO, which could be used as a chemical feedstock, but separation of CO from other gases, especially N
<jats:sub>2</jats:sub>
, is too difficult to be economically viable.
<jats:bold>
Sato
<jats:italic>et al.</jats:italic>
</jats:bold>
(p.
<jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6167" page="167" related-article-type="in-this-issue" vol="343" xlink:href="10.1126/science.1246423">167</jats:related-article>
, published online 12 December 2013) now report that a porous coordination polymer containing Cu
<jats:sup>2+</jats:sup>
ions can selectivity bind CO through serial structural changes reminiscent of allosteric effects in proteins. The separation of CO-N
<jats:sub>2</jats:sub>
mixtures can be achieved with a low input energy for CO desorption.
</jats:p>

DOI： 10.1126/science.1246423

DOI： 10.1002/chem.201602087_references_DOI_HA0Id4AFF1NA3712rUdZdGwQJt6

PubMed

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22000009/

Language：Japanese  

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Language：Japanese   Publisher：CROP SCIENCE SOCIETY OF JAPAN  

DOI： 10.14829/jcsproc.236.0_132

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A disposable extracorporeal centrifugal blood pump utilizing a simply-structured radial controlled magnetic bearing and a torque transmission mechanism has been developed to enhance the durability of the disposable pump head and to reduce blood trauma such as hemolysis and thrombus formation. The prototype blood pump satisfied a requirement of a flow rate of 5 L/min against a head pressure of 800 mmHg. Under sinusoidal base excitation of the maximum acceleration of 9.8 m/s^2 from 10 to 200 Hz and impulse base excitation of 78.4 m/s^2 in the axial and radial directions, the impeller could levitate stably within amplitude of 35 μm in the radial direction, which was smaller than the fluid gaps of 0.3 mm. The normalized index of hemolysis of the prototype was 5.4 ± 0.8 mg/100L, which was about a half of the equivalent value of a commercialized pump having mechanical bearings (BioPump BPX-80). After in-vivo studies with calves for one to two weeks, no thrombus formation was found inside the pump heads.

DOI： 10.1299/jsmekanto.2009.15.213

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

DOI： 10.11522/pscjspe.2009S.0.43.0

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Language：English  

A magnetically levitated centrifugal blood pump (MedTech Dispo) has been developed for use in a disposable extracorporeal system. The design of the pump is intended to eliminate mechanical contact with the impeller, to facilitate a simple disposable mechanism, and to reduce the blood-heating effects that are caused by motors and magnetic bearings. The bearing rotor attached to the impeller is suspended by a two degrees-of-freedom controlled radial magnetic bearing stator, which is situated outside the rotor. In the space inside the ringlike rotor, a magnetic coupling disk is placed to rotate the rotor and to ensure that the pump head is thermally isolated from the motor. In this system, the rotor can exhibit high passive stiffness due to the novel design of the closed magnetic circuits. The disposable pump head, which has a priming volume of 23 mL, consists of top and bottom housings, an impeller, and a rotor with a diameter of 50 mm. The pump can provide a head pressure of more than 300 mm Hg against a flow of 5 L/min. The normalized index of hemolysis of the MedTech Dispo is 0.0025 +/- 0.0005 g/100 L at 5 L/min against 250 mm Hg. This is one-seventh of the equivalent figure for a Bio Pump BPX-80 (Medtronic, Inc., Minneapolis, MN, USA), which has a value of 0.0170 +/- 0.0096 g/100 L. These results show that the MedTech Dispo offers high pumping performance and low blood trauma.

DOI： 10.1111/j.1525-1594.2008.00576.x

PubMed

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Language：English  

DOI： 10.1109/aim.2008.4601723

DOI： 10.1109/tmag.2015.2456338_references_DOI_4dCtw19jTRb6mLrsfta3ScNcDIw

Web of Science

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Language：Japanese   Publisher：The Japan Joint Automatic Control Conference  

DOI： 10.11511/jacc.50.0.29.0

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Language：Japanese   Publisher：The Japan Joint Automatic Control Conference  

DOI： 10.11511/jacc.50.0.31.0

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

In order to implant a maglev blood pump, a biocompatible metallic material should be used in its contact surface with blood or organs. However, the titanium partition wall placed between the maglev rotating impeller and an eddy current displacement sensor may cause a decrease of sensitivity and dynamic range of the sensor. In this study, the measurement characteristics of the eddy current displacement sensor placed behind a titanium wall were investigated experimentally. The sensor satisfied required sensitivity and dynamic range for magnetic levitation when the thickness of the titanium alloy wall was much thinner than its skin depth.

DOI： 10.11522/pscjspe.2006A.0.869.0

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

We have developed a magnetically–levitated (MagLev) disposable centrifugal blood pump with a simply–structured magnetic coupling to realize a durable and low cost disposable pump head. In this report, principles of the proposed magnetic bearing and magnetic coupling are described and applied to a disposable centrifugal blood pump. The pump satisfies the required performance (250 mmHg, 5 l/min) for artificial heart–lung machines, and the amplitude of the impeller oscillation in the controlled directions decreased to 8 mm at 2,000 rpm by repetitive control.

DOI： 10.11522/pscjspe.2006S.0.867.0

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Language：Japanese   Publisher：The Society of Life Support Engineering  

DOI： 10.5136/lifesupport.18.Supplement_40

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Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/bf02806937

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Publisher：Wiley  

<jats:title>Abstract</jats:title><jats:p>A dry developable negative working resist composition comprised of poly(methyl isopropenyl ketone) (PMIPK) and 4‐methyl‐2,6‐di(4′‐azido‐benzylidene) cyclohexanone‐1 was examined. The main photochemical product formed in the resist pattern was found to be a secondary amine which crosslinks PMIPK. Post‐annealing forms a hydrogen‐bonded product which shows a powerful electronic excitation energy quenching effect. The quencher is more powerful than the aromatic compound arising from the azide by post‐annealing only. The residual resist thickness of the negative pattern is about 80 percent of the initial thickness of the coating in spite of all the azide compound remaining in the resist coating. The obtained dry developed resist pattern has a high dry etch resistance. Etchings of Si and SiO<jats:sub>2</jats:sub> were performed by plasma and reactive ion etching, respectively.</jats:p>

DOI： 10.1002/pen.760231804

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/kikaib.48.527

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Publisher：ASME International  

<jats:p>The purpose of this paper is to find an optimum surface geometry of vertical condenser tubes where condensation takes place on the outer surfaces. The guiding principle on optimum condensation performance is to make the thickness of condensate liquid on the surfaces as thin as possible. A vertical tube with longitudinally parallel tiny fins is preferable because condensate is made thinner over the widest possible region. According to an analysis, there are four controlling factors for the optimum fin; sharp leading edge, gradually changing curvature of fin surface from tip to the root, wide groove between fins to collect condensate and horizontal discs attached to the tube to remove condensate. The analytical result is checked by experiments using R-113. The optimum fin shape, fin pitch and spacing of discs are found by numerical calculations for R-113 and water.</jats:p>

DOI： 10.1115/1.3244439

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Publisher：The Japan Society of Applied Physics  

An attempt has been made to establish a practical dry development procedure for submicron pattern lithography in LSI fabrication process with RF discharge plasma under low gas pressure. Poly methyl iso-propenyl keton resist film containing 4, 4'-diazidoe diphenyl ether on a silicon wafer was etched in oxygen plasma at 1.0 torr, 13.56 MHz and 100 W RF power during a few minutes after exposure to deep UV rays through a chrominum mask and heating at 140°C for 30 minutes.

DOI： 10.11470/oubutsu1932.50.145

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Publisher：Elsevier BV  

Abstract This study reveals that, on a finned surface, there exists a region of high heat transfer coefficients in the trough between the crests of fins. A theoretical analysis had predicted a local thinness of the condensate film produced by the capillary action in the trough. This is confirmed by optical measurements of the film thickness in a flow of ethyl alcohol along the model vertical walls. The results of this experiment agree well with the theoretical prediction. Taking these effects into account, the performance of a vertical finned surface is computed using condensation of R-113 and water.

DOI： 10.1016/0017-9310(80)90151-9

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Publisher：Begellhouse  

DOI： 10.1615/ihtc6.170

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/kikai1938.44.2041

DOI： 10.1299/jsmemag.81.714_488_9

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I1948817

Event date： 2025

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Event date： 2024.11

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2024.7

Language：English   Presentation type：Oral presentation (general)  

Plasma skimming in spiral groove bearings (SGBs) has the potential to reduce hemolysis by guiding the red blood cells to escape from the narrow ridge gap with high shear stress force, to the larger groove gap. In our previous study, we designed an optimal SGB-PS that aims to improve plasma skimming inside the bearing gaps and verified its effectiveness under whole blood conditions up to 40% hematocrit level. This study extends our work by evaluating the load-carrying capacity of the optimized SGB design. We first analyzed the load-carrying capacity numerically by calculating the hydrodynamic force based on the Reynolds equation. Then we designed and manufactured an experimental device to measure the generated hydrodynamic force under comparable conditions. Our results indicate that the hydrodynamic force generated by the SGB-PS meets the requirements for our hydrodynamically levitated rotary blood pump and aligns well with our numerical analysis. This research contributes to improving the performance of the SGB for hemolysis resistance in hydrodynamically levitated rotary blood pumps.

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Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

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Event date： 2023

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Event date： 2023

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Applicant：株式会社豊田中央研究所, 株式会社豊田自動織機, トヨタ自動車株式会社, アイシン精機株式会社

Application no：特願2014-066650  Date applied：2014.3

Announcement no：特開2015-192495  Date announced：2015.11

Patent/Registration no：特許第5901678号  Date issued：2016.3

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Applicant：株式会社豊田中央研究所, 株式会社豊田自動織機, トヨタ自動車株式会社, アイシン精機株式会社

Application no：特願2014-066650  Date applied：2014.3

Announcement no：特開2015-192495  Date announced：2015.11

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Applicant：株式会社豊田自動織機, 株式会社豊田中央研究所

Application no：特願2014-062994  Date applied：2014.3

Announcement no：特開2015-182703  Date announced：2015.10

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Applicant：株式会社豊田中央研究所

Application no：特願2013-233127  Date applied：2013.11

Announcement no：特開2015-093542  Date announced：2015.5

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Applicant：株式会社豊田中央研究所

Application no：特願2013-233127  Date applied：2013.11

Announcement no：特開2015-093542  Date announced：2015.5

Patent/Registration no：特許第6331341号  Date issued：2018.5

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