Research On Water Content Measurement With One Sided Capacitance Sensor

Water content measurement instrument works with the principle that permittivity of water is far more bigger than common material. Generally speaking, capacitance sensor needs two plates, the measured medium is kept inside the two plates. In many practical applications, the application of two-plates capacitance sensor is restricted, such as measurement of wall leakage, measurement of terrestrial heating leakage, measurement water content of floor, etc. Based on the practical needs, the paper develops capacitance water instrument. Beginning from the perspective of increasing the depth and decreasing the power consumption, the paper develops water measuring platform and completes primary experiment and model machine in the laboratory environment, the main work is listed as follows:(1)Establish ideal model for the one sided capacitance sensor, and calculate the value of capacitance of the ideal model.(2) Analyze the water measurement system framework, measuring theory and power supply, etc。accomplish design and debug of the portable instrument powered by lithium battery。design low-dissipation sine wave powered circuit,C/V conversion circuit, phase-sensitive demodulation circuit, low pass filtering circuit, and also select the low-dissipation16-bit MSP430F169MCU as circuit chip for the kernel control and data-processing of the flat capacitance sensor. Achieving low dissipation of the whole system.(3) Conduct the experiment of capacitance sensor, select parallel plate capacitance sensor。(4) Complete primary experiment and execution of model machine in the laboratory environment。...