A Low Cost Field Usable Portable Digital Grain Moisture Meter with Direct Display of Moisture (%)

Moisture content of grain is one of the important parameters always considered when deciding the quality and price of grain, at the stage of harvesting, storage, processing and marketing. Grain having excess moisture content, if stored for long duration, will spoil due to insect/fungus infestation. Portable, field usable, and easy-to-use direct moisture (%) display Grain Moisture Meter is a necessity for the benefit of farmers. The types of Grain Moisture Meters available in the market are with look-up tables, which cause inconvenience when carrying out measurements. We have developed a grain moisture meter, which due to its novel design, eliminates this problem and gives moisture (%) directly on a LCD display. The novelty of this instrument is that it is compact, easy-to-use, portable, and field usable. The moisture meter is based on the principle of dielectric constant variations due to change in moisture. Changes of moisture content affect the dielectric constant of the grain, which in turn makes variation in capacitance. The resultant capacitance variation is converted to voltage variation and calibrated in terms of moisture percentage. On the basis of rigorous experiments the meter has been calibrated for wheat, paddy, soybean, sunflower & mustard. However, the user can calibrate the meter at his level for other grains also. The developed instrument is working satisfactorily for all practical purposes in the range of 5-25 % of grain moisture with an accuracy of ± 1% .