Радіоелектронні і комп'ютерні системи (Sep 2019)
NON-CONTACT ELECTRICAL SUPPLY OF IMPLANTS
Abstract
The issues of long-term implants using in the human body are considered. Particular attention is paid to the problem of contactless supply of power to artificial organs with significant energy consumption. Using non-contact energy supply to a fully implanted technical device reduces the risk of infections getting into the patient's body as compared to the use of a power line that is output through internal tissues to the skin surface. The well-known developments of artificial heart apparatus were used as the object of analysis. Their main technical characteristics are considered. The maximum power consumption of these devices is about 20 watts, including models AbioCor. The design of the AbioCor was produced as a fully implanted contactless power unit, but the project was not completed. Although the principle of contactless power supply is undoubtedly an innovative step in the development of implant designs. As a result of the technical implementation of this principle, the following was obtained: it is advisable to use an alternating magnetic field with an inductive coupling between an external and an internal inductor for non-contact energy supply of implants; the use of frequencies of an alternating magnetic field of ~ 100 kHz makes it possible to obtain a compromise solution between the required depth of penetration into biotissues, insignificant heat formation in them and the size and mass of inductors. Under such conditions, the location in the body of the receiving inductor can be determined by medical recommendations. Evaluation experiments were carried out to determine the effective scheme of inclusion of the transmitting and receiving circuits, and the effect on the transmission coefficient of the electrophysical properties of the environment between them. It is shown that for working out of technical solutions of hardware realization of contactless power supply, implantation elements can be placed in saline solution as a model of bioenvironment. It is recommended to use serial element base and circuit solutions used for contactless power supply of radio electronic devices. Also, a quantitative assessment of the additional heat load of the implant on the human body was carried out, since part of the energy of the apparatus and its work, in accordance with the efficiency, inevitably goes into the heat eventually. A simplified calculation of the impact of implant energy losses on the thermal state of the body showed that overheating by 1 °C would be achieved provided the complete insulation of the area, on average, 8.6 hours. This proves the non-critical overheating of the body with implants, and allows the maintenance of a stable body temperature by physiological mechanisms.
Keywords
