A Smart Temperature Sensor and Controller for Bioelectronic Implants

Abstract

Bioelectronic implants have advanced significantly to aid in prostheses and rehabilitation, such as for sensory and motor functions restoration. These implants mainly constitute wireless power transfer, biopotential sensing or electrical stimulation, which invite the risk of localized heating surrounding the implanted hardware. In this paper, a smart $\pmb{0.18}\ \mu \mathbf{m}$ CMOS technology based implantable temperature sensor has been proposed that can be incorporated alongside an implant. The sensor instinctively responds to an unusual temperature fluctuation near the implant and can shut down the system automatically so as to passively regain normal body temperature. The sensor chip has been designed to operate in the region of $\pm \pmb{1}\ ^{\circ}\mathbf{C}$ from base temperature of 37°C (normal human body temperature). The system operates on the basic principle of difference in temperature coefficient between two types of resistor. The proposed sensor consumes only $\pmb{10}\ \mu \mathbf{A}$ current at 2.4 V supply voltage. The sensor has shown reliable performance for simulation process corners and can operate over a wide DC supply voltage range of 2.4 V to 3.6 V.