A Microfluidic pH Sensor with Temperature Compensation Based on Extended-Gate Field-Effect Transistor

PH sensors are widely used in food processing, health monitoring, water quality monitoring, and many other fields. The pH sensor applied in the health monitoring field can realize the real-time measurement of human health information and timely prevent the occurrence of diseases by improving people's health levels. However, these sensors have some challenges in body fluid collection and temperature compensation. Here, we developed a pH sensor based on an extended-gate field-effect transistor (EGFET) with microfluidic channels and a temperature sensor to overcome these challenges. The sensor is prepared using a low-cost, solution-based process in which a temperature sensor is used for body temperature measurement and temperature compensation, and a microfluidic channel is used for body fluid collection. This pH sensor can measure both body temperature and pH of body fluid, where the temperature coefficient of resistance (TCR) of the temperature sensor is up to 5.17%, and the measurement result of body temperature is only 0.17 ℃ different from that of the gold standard. The pH sensitivity is 58.41 mV pH−1, and the pH value is only 0.066 deviating from the standard pH value. The sensor is expected to be used on a large scale in the applications of wearable health monitoring.