A Fully Integrated 11.2 mm2 a-IGZO EMG Front-end Circuit on Flexible Substrate Achieving up to 41dB SNR and 29MΩ Input Impedance

摘要： A biopotential front-end circuit is designed and fabricated using a-IGZO TFTs on flexible plastic substrate. Its input chopper provides both noise reduction and Frequency Division Multiplexing among multiple front-ends in an array. Measurements of the front-end at chopping frequencies from 5 to 8 kHz show a gain in the range of 24.9 - 23.1 dB, bandwidth of 5.4 to 5.2 kHz, input noise in the EMG band ranging from 125 μVRM S to 31.4 μVRM S, and an input impedance of 29.6 to 23 M ?. At different chopping frequencies, the SNR in the EMG band is respectively 29, 32.3, 38, 41 dB, enough to monitor Muscle Fibre Conduction velocity. This is achieved in a total area of 11.2 mm2 and with 1.3 mW power consumption. In-vivo recordings of EMG from the forearm of a person using the fabricated front-end and standard gel electrodes have been performed. The measurements show EMG bursts with a maximum amplitude of 1.6 mV, which is within the physiological range for this muscle. The proposed circuit achieves an 8.9X reduction in size compared to previous front-ends fabricated on flexible foil for EMG applications, enabling a spatial resolution in the order of a few millimetres, with great benefit for the diagnosis of neuromuscular disorders.