Temperature-Compensated pH Microelectrode Array Sensors Based on Copper-Oxide/Polyaniline Modification

pH is an important indicator of water quality. Therefore, developing accurate, efficient, and economical pH sensors is crucial. This paper presents a low-cost and highly robust miniature pH sensor chip with a temperature compensation function. The chip was manufactured using microelectricalmechanical systems technology. The surface of the chip comprised three three-electrode pH sensors and a Pt resistance temperature sensor. Moreover, CuO/polyaniline was modified for use as a pH-sensing material in the chip. To compensate for the temperature, a sandwich-plate sensor was utilized, which was integrated with a platinum-resistance heater. The experimental results show that the pH sensor had a high sensitivity of 0.288 mA/pH and high linearity of $R^{2} = 0.9998$ . Furthermore, the response time of the chip was less than 4 s, the sensitivity of the temperature sensor was $0.949\Omega /^{\circ }\text{C}$ , and the sensitivity of the temperature variations to the power of the heater was 0.3126 °C/mW. Finally, the pH sensor chip was further calibrated via multiple linear regression. Compared with commercial pH meters, the chip demonstrated high accuracy and remarkable temperature compensation.