Millimeter-Sized 0.1pM-LoD Wireless 16-Channel Organic Electrochemical Transistors Based Electrochemical Sensing SoC

This paper proposes a millimeter-sized, high-sensitivity, wide-dynamic-range 16-channel electrochemical sensing SoC with integrated thin-film organic electrochemical transistor (OECT), utilizing ultrasonic wireless power and backscatter wireless communication technology. A bidirectional current conveyor and resistor (CC+R) potentiostat with duty-cycle control is introduced to minimize the static current consumption by reducing the duty cycle of the OECT amplification process. Additionally, the programmable gain amplifier's (PGA's) sampling capacitor is repurposed for small current-to-voltage conversion, extending the measurement range with minimal overhead. The system further integrates an active full-wave rectifier with backscatter amplitude modulation, supporting a wide range of received pulse amplitudes, variable time-of-flight (ToF), and tunable ultrasound frequencies. The design is fabricated using a 180 nm CMOS process. Experimental result features a sensing current measurement range of 184 dB, with a minimum current noise of 1.25 pA${}_{\text{rms}}$. The power consumption of the single-channel system is 16.3 $\mu W$. The design was validated for the detection of inflammatory factors, achieving a limit of detection (LoD) as low as 0.1 pM and the linearity with $R^{2}$ greater than 0.95.