A 0.5µVrms 12µW patch type fabric sensor for wearable body sensor network

Abstract

A 0.5μVrms, 12μW wirelessly powered patch type fabric sensor is presented for wearable body sensor network to continuously monitor personal bioelectric signals. Thick film electrodes are screen printed on the fabric with various metal components and their impedances of ≈100kΩ are characterized. A 2-stage nested chopped analog readout front end (AFE) is optimized for the fabric sensor with reduced electrode referred noise performance of 0.5μVrms. A 10b folded SAR ADC reduces capacitive DAC (CDAC) size and relaxes the power budget of ADC driver by 94%. The proposed fabric sensor operates with system resolution of 9b and CMRR>106dB. The chip fabricated with 0.18μm CMOS technology, the fabric sensor stacked by screen printed inductor (diameter=3cm and # turns=4) can measure the ECG and EMG signals with wirelessly transmitted power through inductive coupling.