Wireless Telemetry System for a SAW Based Microvalve

Inductively coupled RF telemetry is an optimal method for both power supply and data transmission in long term artificial implants due to small size, high reliability, and extended life span of the device. In this research, we propose the use of the same technique for secure remote interrogation and powering of a human implantable, Surface Acoustic Wave (SAW) correlation based, passive microvalve. This is carried out by interrogating the microvalve with a Barker sequence encoded BPSK signal. In this paper we present the development of a FEM model for the derivation of the induced voltage on a miniature (2.5×2.5×1 mm), inductively coupled, bio-compatible spiral antenna/coil, interrogated by a 7.5×7.5×0.2 cm spiral antenna/coil in the near field. The amount of power transferred at a 30-160 MHz range was derived using the S21 coupling response when the two antennas are separated by a human body simulant of 5 cm depth. Furthermore, the effect of varying magnetic coupling on the induced voltage, due to the misorientation of coils/antennas is analysed