Implantable Wireless Microsystem for Physiological Functions Control

This work present a new solution for wireless control of functional electrical implantable systems. A microsystem, with integrated antenna, is proposed to replace the cables implanted during standard surgical procedure. The integrated antenna allows the transmission of energy from an external controller to the internal actuator, avoiding therefore long transmission cables within the body, quite susceptible to failures. The main target under analysis is a solution for controlling the inferior urinary system. The use of such device in restoring the urinary function of injured persons, employing sacral anterior root stimulation (S2-S5), is known to be extremely effective in increasing bladder volume, promoting full emptying of the bladder, reducing enormously the bladder infections and improving greatly the patient´s quality of life. The feasibility of implanting the proposed microsystem directly next to the base of the spine, is examined. Experimental data is obtained to characterize: tissue attenuation for different carrier frequencies, misalignment between the external and internal antenna and distance between them. It was verified the possibility to use a frequency of 13.5 MHz for a tissue thickness of 4 cm.