RESISTIVITY OF COTTON LINT FOR MOISTURE SENSING

The international cotton industry needs an inexpensive yet accurate method to determine the moisture content of cotton. Basic studies were conducted to ascertain the applicability of electrical resistance to measuring moisture content. The resistance of cotton lint samples of varying moisture content, which were loaded into a series of acrylic holders with aluminum ends and compressed to 0.3 g/cm3, was measured. The holders varied in sample thickness from 1 to 4 cm and in sample cross-sectional area from 1 to 40 cm2. The resistance was found to vary with sample thickness as expected, but the resistivity did not vary with sample cross-sectional area in the expected way. Relationships relating sample moisture content to sample resistance and sample geometry were examined. Models were found which fit the data well; the residuals varied inversely with sample moisture content and sample circumference.