A Simple Chickpea Grain Moisture Measurement System

Different varieties of chickpea grains are harvested extensively in India subcontinent. Moisture measurement in chickpea grains is essential in maintaining the seed quality, its food value, crops harvest and to prevent wastage. There is no dedicated moisture meter for chickpeas. This paper investigates capacitive sensors to evaluate the moisture content of various chickpea grains. Two different types of capacitors such as a dual parallel plate and a single parallel plate are designed and fabricated with proper care of parasitic capacitances in a cost effective manner. Experiments were conducted on four types of grains such as brown chickpea (small, medium size), green chickpea and Kabuli (big size) to determine the electrical response parameters at 100 kHz frequency with moisture variation from 8 to 30% (weight). The sensor capacitance value and the moisture content of grains are correlated linearly. Finally, the sensor was interfaced to an electronic circuit to calibrate the voltage signal to display moisture directly. Key distinguishing features of the sensors are high sensitivity, high precision (average standard deviation < 0.05 %), and inexpensive fabrication. The calibration curves can be used to measure moisture as well as type of grains (identification). The relative permittivity of the grain can be directly determined using the double parallel plate sensor. The method adopted for measurement is sample, fast and non-destructive.