Active Electrode With a High-Gain a-IGZO TFT Bootstrap Amplifier for Surface Electromyography Signal Acquisition

Surface electromyography (sEMG) signals are crucial bioelectrical signals that offer valuable insights into muscle activity and motor control. However, sEMG signals are susceptible to interference from various sources, including environmental factors and physiological crosstalk, power noise, and motion artifacts. These interferences can compromise the quality and accuracy of the sEMG signals. The challenge remains to achieve high temporal and spatial resolution for detecting sEMG signals. In this study, novel active electrodes with a high-gain pixel-level amplifier were developed using amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) technology to collect sEMG signals. To achieve high signal gain, a wide input voltage range, and low noise, we designed a bootstrap negative feedback amplifier circuit based on a-IGZO TFTs. The active amplifier circuit exhibited a signal gain of approximately 21.9 dB at a driving voltage of 15 V and a gain bandwidth of 1.5 kHz. Compared with the traditional passive electrode, the signal-to-noise ratio (SNR) of the signal collected by the active electrode is 194% of the passive electrode, and the signal reliability is significantly improved. As a result, the active electrodes present distinct advantages in terms of stability, flexibility, and high gain. This innovation paves the way for high-quality acquisition of surface EMG signals.