Bio-Potential Sensing System With Monolithically Integrated Electrode Array and Analog Front-Ends on a Flexible Substrate

Based on a 300-°C, indium-gallium-zinc oxide (IGZO) thin-film transistor (TFT) technology, a bio-potential sensing system consisting of an electrode array and analog front-ends (AFEs) monolithically integrated on a flexible polyimide (PI) substrate is described. Blanket thermal predrive-in of hydrogen under metal-coverage has been conducted to boost the conductivity of the source/drain (S/D) regions of a TFT, thus increasing the current-drive capability of the TFT. Polyethylene terephthalate (PET) as a temporary substrate has been employed during laser lift-off (LLO) of the flexible substrate, thus mitigating stress-induced film cracking and improving TFT yield. The fabricated AFE exhibits a differential gain of 62 dB and a bandwidth of 900 Hz. The utility of the system has been demonstrated by electrophysiological mapping of the forearm muscles when actuating a grip dynamometer.