Evaluation of the Performance of a Newly Developed Wireless Temperature and Moisture Sensor for Rice under Various Levels of Temperature, Moisture Content, and Dockage

Abstract. Monitoring on-farm, in-bin natural air drying process of rice is critical to achieve optimum milled rice quality, milling yields, and maximize profits to growers and processors. Engineering tools such as temperature/humidity cables with sensors for grain condition monitoring, and mobile applications have emerged to provide significant improvements in quality control and automation of the drying process. This research seeks to improve the performance of a recently developed, novel wireless probe for sensing temperature and moisture content of rice. The specific objective is to test the accuracy and precision of the measurements over a wide range of rice temperature (20°C to 60°C), moisture content (13% to 25% wet basis), and dockage levels (0 to 10% by weight). Wireless probes designed and built in collaboration with Deacon Technologies LLC were used in this study. The probes were calibrated against thermocouple readings for temperature measurements and standard oven method measurements for moisture content. Experiments were performed in triplicates using three different probes and three metal containers with rice samples to check the accuracy of the probes and to determine the variability amongst different probes. The probes were accurate due to the strong regressions found between the measured and true values of temperature and moisture content. The ANOVA analysis showed that there was no significant difference within different probes both for temperature (p = 0.17) and moisture content (p = 0.48) measurements. Calibration equations were developed to further reduce the variance in the probe measurements. Both for temperature and moisture content measurements, the calibration equation coefficients were statistically significant with positive slopes and small standard errors (less than 0.5). Thus, these probes could be handy for on-farm in-bin rice temperature and moisture monitoring; with the merits of portability, easy set-up and tear down, low initial and maintenance cost, and precise and accurate measurements. Keywords: Calibration, Dockage, Moisture content, On-farm in-bin drying, Rough rice, Temperature, Wireless probe.