Mathematical Model and Circuit Design of Capacitance Sensor for Water Content of Plant
Ruxin Li · Jieshui guan'gai · 2008
At present,the judgment of water content condition of plant is mostly through the soil and environment moisture.On thebasis of the study onthe work principle of the parallel plate capacitance sensor,the method,in which capacitance sensor is adopted tod as solid phase,liquid phase and gas phase,is put forward in this paper.The mathematical model with the parallel and series connection of threephase mediumfor the water content measurement is established and numerical si mulationis conducted.It is found that the plate ca-pacitance value has corresponding relation with the water content of measured medium.So the parallel plate capacitance sensor candirectly measure the water content of plant and the problems of ti me-lag andlowaccuracy are solved.The model-establishing methodof parallel connection of three phases mediumcan be taken as the opti mal solution for the theory analysis of sensor systems.Moreo-ver,based on the theory analysis,the structural design of sensor circuit is preli minarily analyzed and introduced in this paper.