Printed Electronics by Plasma Spraying: Case Study for High Temperature Sensors

Temperature sensors are critical components in many industrial and research applications, particularly in harsh environments where high temperatures, corrosion and mechanical stress are prevalent. In this paper, we investigate the use of plasma spray technique as a versatile and simple method to print multipoint thermocouples and resistance temperature detectors (RTDs) based on NiCr-NiAl coatings on steel and ceramic substrates using stencil masking and laser scribing. The thickness of alumina the dielectric layer was optimized using metal-insulator-metal test. The thermoelectric properties of the printed thermocouples were investigated up to 1000 °C. The thermal independency of printed thermocouples and the capability of multilocation measurement at the surface on the same substrate was demonstrated. The thermoelectric properties of the printed RTD were investigated up to 850 °C. The electrical resistance of the RTD sensor is linear with the temperature variation from room temperature to 500 °C. The oxidation effect of the printed sensor metallic layers at high temperature was investigated and discussed.