Battery-powered Wearable Utilizing Flexible Printed Circuit-based Organic Electrochemical Transistor Embedded with Simple Circuits of Voltage Divider and Regulator for Biosignal Measurement
With the distinctive advantages of high transconductance, low operating voltage, mixed ionic-electronic conductivities, and dynamic versatility, organic electrochemical transistor (OECT) has emerged as a promising wearable technology capable of measuring various biophysical and biochemical signals. Despite the intensive research efforts towards enhancing its wearability, challenges related to signal conversion, voltage sourcing, and manufacturing scalability are seldom addressed. Herein, we report a compact and easy-to-build integrated module that provides stable biasing from batteries while enabling current-to-voltage conversion and additional amplification of OECTs responses. Given the known amplitude of target signals, transistor bias and amplification gain can be adjusted easily on site by tuning two key resistance values and ensuring sufficient battery voltage. Furthermore, the flexible OECTs in this work were fabricated through an industrial manufacturing process for flexible printed circuits (FPC), in which the polymeric channel material and device architecture were both customized to accommodate the fabrication constraints. Notably, preliminary measurements based on the battery-powered unit comprising our OECT and module demonstrate significantly amplified bio-signals compared to electrodes. The successful acquisition of on-body electrocardiogram voltages further underscores the potential of this platform to support current and future OECT interfaces.