植込み型電子装置への超音波による制御信号伝送方式

抄録

A transmission system of control data from outside of human body into inside to change the operation conditions of implanted electronic apparatus is presented. Since the system is to be operated in the atmospheric noises caused by electromagnetic field existing in the surroundings of human life, the media, frequency and modulating type of the data transmission were examined. So pulse amplitude modulated ultrasonic waves of 1MHz, 600bit/s, was selected. The tranmitter consists of key board, microcomputer, modulator and sending transducer, while the receiver consists of wave receiver, demodulator, microcomputer and control circuit. New data input on the key board are converted into asynchronous format signal by the microcomputer, and pulse modulates the amplitude of ultrasonic carrier waves. The received signal is, meanwhile, converted to control signal by the microcomputer to be input into implanted apparatus. For application of this system to cardiac pacemaker, the transmitted data signal is composed of 8-bit opening flag, 8-bit pulse rate data, 4-bit pulse voltage data, 4-bit pulse with data and 8-bit closing flag. Those datas are sent 6 times repeatedly so as to prevent transmission error. Received data are compared with one another, and, when all the data are same, the microcomputer accepts them as the new data and transmitted into implanted apparatus to change operation condition. An experimental transmission test of this system took place with 25mm thick beef meet, likening to human body. In this test, lead zicronate titanate ceramic transducer of 40mm dia. and 1MHz resonance frequency were applied to wave transmitter and receiver, and the operation conditions of pacemaker could be changed to such extent as 42-124pulse/min of pulse rate, 1.0-4.0V of pulse voltage and 1.0-3.0ms of pulse width.