Permittivity measurement of wood based on an uniplanar capacitance sensor

An uniplanar capacitance sensor is a core device of high-precision instrument applied to measure wood moisture content, permittivity, etc. In nature, it is a special case of a capacitance sensor of unspecific form. This paper describes the numerical solution to a mathematical model of uniplanar capacitance sensor. An uniplanar capacitance sensor with specific size was taken as an example in this study, and discrete difference scheme - a numerical analysis method - was utilized to establish the discrete approximate model, which is convenient to calculate and study the mathematical model of partial differential equations established in previous research work. The approximate model obtained was adopted to analyze the working conditions of an uniplanar capacitance sensor and to find out the relationship between the permittivity e of wood and the capacity C of capacitance sensor. This result can be applied to the practice of engineering and the method presented in this study is easily extended to uniplanar capacitance sensors of general size and structure.