Research on a Miniature Multiparameter Water Quality Sensor Chip and a System with a Temperature Compensation Function

Abstract

This paper presents a multiparameter water quality sensor chip with temperature compensation. The sensor chip was manufactured using microelectromechanical system (MEMS) technology. The surface of the chip integrated pH, dissolved oxygen (DO), ammonia nitrogen, and temperature sensors. To compensate for the solution temperature, the chip was also designed with a sandwich, plate-type serpentine Pt resistance heater. The experimental results showed that the pH sensor had a high sensitivity of 0.288 mA/pH with good linearity ( $R^2=0.9998$ ), the sensitivity of the temperature sensor was 0.949 Ω/°C, the sensitivity of the ammonia nitrogen sensor was 0.1139 mA/ppm, the sensitivity of the dissolved oxygen (DO) sensor was 2.22 μA/ppm, and the sensitivity of the temperature changes with respect to the heater power was 0.3126°C/mW. Compared with a single water quality parameter sensor, the as-prepared sensor chip could simultaneously detect multiple parameters of a water sample and had a good temperature compensation effect. Moreover, the sensor chip was small in size, rugged, and highly accurate.