Corn Moisture Measurement using a Capacitive Sensor

Corn moisture content is the main factor of effecting corn safe transportation and storage, and is also an indispensable measurement part when it is used to feed, food and industry. Due to large particle size, corn will produce large gap during measuring moisture content. Because air has much influence on dielectric constant of the device, moisture content is not precision. In all kinds of corn moisture measurement methods, capacitance method becomes the main method with simple structure, low cost and online measurement. This paper designs a sensor for measuring the corn moisture that uses a capacitance detection circuit based on the relationship between the capacitance and the dielectric constant of the corn. In addition, different operating modes of the detection circuit are analyzed. The relationship between the moisture content of corn and the sensor capacitance is obtained through experiment and a binary cubic equation is obtained by the least squares fitting method.