Implementation of A High-precision pH Sensor

摘要

A high-precision pH sensor based on electrochemical principle is proposed in the paper. The principle of the sensor, the performance parameters of MCU, hardware architecture and experiment are introduced. The NEC microprocessor, which is low-power and high stability, is adopted as core processor. The three operational amplifiers same-phase parallel amplifying circuit not only matches the impendence of the pH combination electrode, but also eliminates the impact of wire resistance on pH measurement. The system's capacity of resisting disturbance is improved. Using 18-bit AD converter, which has programmable amplifier on chip, improves measurement accuracy. Both theoretical analysis and experimental results show the effectiveness of the pH sensor. A full description of the pH sensor and implementation are presented.