RESUMEN
This paper describes the application of a proposed spiral coil to the transformer of a transcutaneous energy transfer system for a totally implantable artificial heart. To reduce the number of rectifier components in the power receiving circuit, the shape of the power receiving transformer was reviewed. The results indicated that the power transmission efficiency between the transformers was almost the same as that of the receiving transformer with the same shape. In addition, the calculations indicated that the power transmission efficiency including that of the power receiving circuit was increased, and the number of components in the power receiving circuit was reduced.
Asunto(s)
Corazón Artificial , Suministros de Energía Eléctrica , Transferencia de Energía , Diseño de EquipoRESUMEN
When patients are fitted with a totally implantable artificial heart (TAH), they need to be implanted with two additional devices: one for the transmission of energy and one for information. However, this is a cumbersome process that affects the quality of life of the recipient. Therefore, we investigated the use of electromagnetic coupling for the transmission of energy and information and the possibility of unifying two transcutaneous transformers for the simultaneous transmission of energy and information. While unifying the transformers, it is important to suppress the electromagnetic coupling between energy and information transmission. Therefore, we ensured that the electromagnetic fields generated from the transformer windings for the transmissions of information and energy intersected perpendicularly. If the fields are perpendicular, the electromagnetic coupling between the energy and information transmissions will be suppressed significantly. The characteristics of the simultaneous transmission of information and energy using the unified transcutaneous transformer, developed experimentally, were evaluated by changing the number of windings used for the transmission of information. The electromagnetic coupling between the energy and information transmissions was suppressed by determining the direction of the magnetic field. Moreover, the optimum number of transformer windings required for the simultaneous transmission of energy and information was determined. We concluded that the externally coupled transcutaneous transformer unified for the simultaneous transmission of energy and information performed with good transmission characteristics.
Asunto(s)
Suministros de Energía Eléctrica , Corazón Artificial , Implantación de Prótesis , Calidad de Vida , Campos Electromagnéticos , Diseño de Equipo , HumanosRESUMEN
This paper reports on the current density and specific absorption rate (SAR) analysis of biological tissue surrounding an air-core transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue is analyzed by the transmission line modeling method, and the current density and SAR as a function of frequency, output voltage, output power, and coil dimension are calculated. The biological tissue of the model has three layers including the skin, fat, and muscle. The results of simulation analysis show SARs to be very small at any given transmission conditions, about 2-14 mW/kg, compared to the basic restrictions of the International Commission on nonionizing radiation protection (ICNIRP; 2 W/kg), while the current density divided by the ICNIRP's basic restrictions gets smaller as the frequency rises and the output voltage falls. It is possible to transfer energy below the ICNIRP's basic restrictions when the frequency is over 250 kHz and the output voltage is under 24 V. Also, the parts of the biological tissue that maximized the current density differ by frequencies; in the low frequency is muscle and in the high frequency is skin. The boundary is in the vicinity of the frequency 600-1000 kHz.
Asunto(s)
Suministros de Energía Eléctrica , Electrónica/instrumentación , Corazón Artificial , Modelos Cardiovasculares , Efectividad Biológica Relativa , Telemetría/instrumentación , Transductores , Carga Corporal (Radioterapia) , Simulación por Computador , Diseño Asistido por Computadora , Transferencia de Energía , Diseño de Equipo , Análisis de Falla de Equipo , RadiometríaRESUMEN
Transcutaneous energy transmission (TET) that uses electromagnetic induction between the external and internal coils of a transformer is the most promising method to supply driving energy to a totally implantable artificial heart without invasion. Induction-heating (IH) cookers generate magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with the external and internal coils of the transcutaneous transformer. This will affect the performance of the TET and the artificial heart system. Hence, it is necessary to improve the magnetic field immunity of the TET system. During operation of the system, if the transcutaneous transformer is in close proximity to an IH cooker, the electric power generated by the cooker and coupled to the transformer can drive the artificial heart system. To prevent this coupling, the external coil was shielded with a conductive shield that had a slit in it. This reduces the coupling between the transformer and the magnetic field generated by the induction cooker. However, the temperature of the shield increased due to heating by eddy currents. The temperature of the shield can be reduced by separating the IH cooker and the shield.
Asunto(s)
Suministros de Energía Eléctrica , Fenómenos Electromagnéticos , Corazón Artificial , Transferencia de Energía , Diseño de Equipo , MagnetismoRESUMEN
The electromagnetic compatibility of implantable or wearable medical devices has often been evaluated using human phantoms to electrically mimic biological tissues. However, no currently existing test fixture can measure the electrical characteristics of gel-like materials. In this paper, we report the development of a new test fixture that consists of a coaxial tube whose outer conductor is divided along the axial direction into two sections, which facilitates filling and removal of gel-like materials in order to measure their electrical characteristics. Using this test fixture, we measured the electrical characteristics of a cow's muscular tissues up to 1 h post-mortem; these measurements allowed us to obtain the relative permittivity and conductivity of the biological tissue, which should help to enable the design of new human phantoms.
Asunto(s)
Equipos y Suministros Eléctricos , Músculos/citología , Animales , Bovinos , Impedancia Eléctrica , Fenómenos Electromagnéticos , CarneRESUMEN
Transcutaneous energy transmission is useful for improving patient quality of life and for supplying energy to implantable devices noninvasively. To supply highly efficient energy transmission through the skin, it is necessary to increase the coupling factor between the coils and increase the inductance of each coil. In this study, the optimal shape required for the coils to increase the coupling factor was investigated.
Asunto(s)
Suministros de Energía Eléctrica , Prótesis e Implantes , Algoritmos , Transferencia de Energía , Diseño de Equipo , Humanos , Calidad de Vida , Tecnología InalámbricaRESUMEN
Human body communication (HBC) is a new communication technology that has presented potential applications in health care and elderly support systems in recent years. In this study, which is focused on a wearable transmitter and receiver for HBC in a body area network (BAN), we performed electromagnetic field analysis and simulation using the finite difference time domain (FDTD) method with various models of the human body. Further we redesigned a number of impedance-matched electrodes to allow transmission without stubs or transformers. The specific absorption rate (SAR) and transmission characteristics S21 of these electrode structures were compared for several models.
Asunto(s)
Impedancia Eléctrica , Tecnología Inalámbrica , Anciano , Electrodos , Campos Electromagnéticos , Diseño de Equipo , Humanos , Japón , Masculino , Modelos Teóricos , Procesamiento de Señales Asistido por Computador , Interfaz Usuario-ComputadorRESUMEN
We proposed the calculation method of the ventilation threshold using the noncontact respirometry under pedal stroke motion. By the simultaneous measurement with the expiration gas analyzer, we examined the effectiveness of the proposal method. There was high correlation over 0.8 between ventilation variations calculated by our proposed method and the expiration gas analyzer. On the other hand, the correlation between ventilation thresholds calculated by our proposed method and the expiration gas analyzer is 0.735. In this experiment, the sufficient examination seemed to be difficult on the correlation, since the difference between the systemic aerobic capacities of the examinees is small.
Asunto(s)
Prueba de Esfuerzo/instrumentación , Ventilación Pulmonar , Prueba de Esfuerzo/métodos , Espiración/fisiología , Humanos , Mecánica Respiratoria/fisiologíaRESUMEN
This paper reports on the electromagnetic influences on the analysis of biological tissue surrounding a prototype energy transmission system for a wireless capsule endoscope. Specific absorption rate (SAR) and current density were analyzed by electromagnetic simulator in a model consisting of primary coil and a human trunk including the skin, fat, muscle, small intestine, backbone, and blood. First, electric and magnetic strength in the same conditions as the analytical model were measured and compared to the analytical values to confirm the validity of the analysis. Then, SAR and current density as a function of frequency and output power were analyzed. The validity of the analysis was confirmed by comparing the analytical values with the measured ones. The SAR was below the basic restrictions of the International Commission on Nonionizing Radiation Protection (ICNIRP). At the same time, the results for current density show that the influence on biological tissue was lowest in the 300-400 kHz range, indicating that it was possible to transmit energy safely up to 160 mW. In addition, we confirmed that the current density has decreased by reducing the primary coil's current.
Asunto(s)
Endoscopios en Cápsulas , Endoscopía Capsular/métodos , Diseño Asistido por Computadora , Suministros de Energía Eléctrica , Magnetismo/instrumentación , Modelos Biológicos , Telemetría/instrumentación , Simulación por Computador , Diseño de Equipo , Análisis de Falla de Equipo , Dosis de Radiación , Radiometría , Efectividad Biológica RelativaRESUMEN
We proposed the non-contact measurement method of the respiratory movement under pedal stroke motion, by the application of optical technique. By the simultaneous measurement with the expiration gas analyzer, we examined the effectiveness of the proposal method. As the results, we clarified that the calculated value obtained by our proposal method is highly correlated with the tidal volume expiration measured by the expiration gas analyzer.
Asunto(s)
Prueba de Esfuerzo/instrumentación , Mecánica Respiratoria/fisiología , Prueba de Esfuerzo/métodos , Espiración/fisiología , Humanos , Intercambio Gaseoso PulmonarRESUMEN
This paper reports on the electromagnetic influences on the analysis of biological tissue surrounding a prototype energy transmission system for a wireless capsule endoscope. Specific absorption rate (SAR) and current density were analyzed by electromagnetic simulator in a model consisting of primary coil and a human trunk including the skin, fat, muscle, small intestine, blood and backbone. SAR and current density as a function of frequency and output power were analyzed. The SAR was below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). At the same time, the results for current density show that the influence on biological tissue was lowest in the 300-400 kHz range, indicating that it was possible to transmit energy safely up to 100 mW.
Asunto(s)
Endoscopios en Cápsulas , Suministros de Energía Eléctrica , Modelos Biológicos , Radiometría/métodos , Efectividad Biológica Relativa , Telemetría/instrumentación , Carga Corporal (Radioterapia) , Simulación por Computador , Transferencia de Energía , Humanos , Dosis de Radiación , Telemetría/métodosRESUMEN
This paper reports on the specific absorption rate (SAR) and the current density analysis of biological tissue surrounding an air-core type of transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue surrounding the transformer was analyzed by the transmission-line modeling method, and the SAR and current density as a function of frequency (200k-1 MHz) for a transcutaneous transmission of 20 W were calculated. The model's biological tissue has three layers including the skin, fat and muscle. As a result, the SAR in the vicinity of the transformer is sufficiently small and the normalized SAR value, which is divided by the ICNIRP's basic restriction, is 7 x 10(-3) or less. On the contrary, the current density is slightly in excess of the ICNIRP's basic restrictions as the frequency falls and the output voltage rises. Normalized current density is from 0.2 to 1.2. In addition, the layer in which the current's density is maximized depends on the frequency, the muscle in the low frequency (<700 kHz) and the skin in the high frequency (>700 kHz). The result shows that precision analysis taking into account the biological properties is very important for developing the transcutaneous transformer for TAH.