An Active Multielectrode Array for Collecting Surface Electromyogram Signals Using a-IGZO TFT Technology on Polyimide Substrate

The surface electromyogram (sEMG) signals produced by living bodies play a significant role in biological applications. However, an active multielectrode array (MEA) having a high spatiotemporal resolution, flexibility, and high gain is still an enormous challenge for accurate sEMG detection. Here, a flexible active MEA based on the diode-connected load inverter is proposed and fabricated for collecting sEMG signals using amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) technology on the polyimide (PI) substrate. To obtain the good gain effect and low-noise active MEA, the width–length ratio of the transistors and the suitable impedances are systemically designed. Moreover, the optimized circuit exhibits good bias stability, excellent uniformity in electrical performance, and outstanding mechanical durability, which can ensure reliable sEMG detection. With the combination of the a-IGZO TFTs, the active MEA has an approximate 15-dB signal gain under a low driving voltage of 5 V. Measuring the sEMG of the muscle groups below the thumb with our developed flexible active MEA, the amplitude value of sEMG signals is successfully amplified and the noise fluctuation is obviously reduced. Thus, the active MEA has certain advantages in large-area preparation, stability, flexibility, and high gain, which opens a new avenue for the accurate sEMG signal measurements.