Abstract:

The present study investigates a circuit system for measuring micro-capacitive sensors based on the principle of differential operation, by which the correlation between the effective value of the output voltage and the capacitive sensor to be measured is theoretically explored, and the relationship between the sensor’s capacitance and the output voltage is verified. The Wien bridge oscillator circuit acts as a stable signal source, and the capacitive sensor to be measured is connected to the differential operation circuit, thus the output signal is strained by the capacitive sensor to be measured. The output signal of the differential circuit is converted by the main control chip from analog signal to digital signal, and the sensor measurement result can be printed on the serial port or sent to the external receiving device via wireless module, making the measurement of small capacitive sensor smarter. The present system demonstrates that it is a complete linear correlation between the sensor capacitance and output voltage, and the result is easy to process and not susceptible to distributed capacitance. In addition, this system can realize multi-range sensors’ measurement by adjusting the resistance value of the differential circuit , whose structure is concise and has good anti-interference performance.