Design and Fabrication of Nondestructive Capacitive Sensors for the Moisture Measurement in Chickpeas and Mustard Seeds

Abstract

Moisture in food grains, including chickpea and mustard seeds, plays a crucial role in their storage and processing, thus ensuring food quality. It helps in the improvement of preservation techniques. Moisture in these materials is an age-old problem; hence, it is important to monitor it in real time. The conventional gravimetric method is manual and time-consuming; some online electrical techniques are available in which grains are considered as a dielectric material, but they are relatively complex and costly. This present work describes a nondestructive concentric fringing field (CFF) capacitive sensor to detect moisture (4–33% by absolute weight) of chickpea grain and (12–30% by absolute weight) mustard seed. First, the proposed CFF sensor was modeled, and then three distinct concentric sensors were designed, simulated, fabricated, and experimentally validated to determine moisture in chickpea grains and mustard seeds. The capacitance values of all the sensors approximately linearly varied with the changes in the moisture of the grains. The average sensitivity of the most sensitive sensors was close to 20 fF/% wt for chickpeas and 31 fF/% wt for mustard seeds. The proposed sensor is sensitive, nondestructive, easy to use, inexpensive, and fast.