Thick Film Thermistor Sensor for Measuring Temperature Profile of Ground Top Layer

Abstract

© 2018 IEEE. A row of NTC thick film segmented thermistors was used to form a novel ground temperature profile sensor named GST-1, with numerous measuring points, densely packed and equidistantly distributed over half a meter length. The sensor was protected against humidity by conformal coatings, silicone resin, plastic mini wire trunking conduit and aluminum tube that were vertically positioned in the hole drilled in the clay-silt top layer of the ground. Steinhart-Hart equation and data processing by Excel were used for conversion of thermistor DC resistances to temperature values. The ground temperature profiles measurements were performed early in the morning (7.00 am) and early in the afternoon (14.00 pm) each day over a long period of time. The air temperatures were also recorded and compared to ground temperatures. Detailed measuring results obtained by the novel sensor where presented daily and monthly as a function of sensors positions (depth) and time (days). Sensitivity, accuracy and long-term stability of the sensor were also discussed. Keywords: Temperature sensors, thick film thermistors.