Low-Cost Extended-Gate Field Effect Transistor Sensing System Based on A Channel Structured Reference Electrode

This paper reports a low-cost extended-gate field effect transistor based nitrate sensor using a microfluidic channel based Reference Electrode (μcRE). The μcRE is integrated with a MOSFET to increase potential stability for long-term measurement. The sensor also includes a readout circuit to save or remotely transmit data to a smartphone. The μcRE exhibits a 0.5 mV/hour drift rate and the sensor offers a 0.997 R-Squared value to the linear fitting for potentiometric measurement of nitrate in water.