Wireless Passive Ceramic Sensor for Far-Field Temperature Measurement at High Temperatures

A passive wireless high-temperature sensor for far-field applications was developed for stable temperature sensing up to 1000 degrees C. The goal is to leverage the properties of electroceramic materials, including adequate electrical conductivity, high-temperature resilience, and chemical stability in harsh environments. Initial sensors were fabricated using Ag for operation to 600 degrees C to achieve a baseline understanding of temperature sensing principles using patch antenna designs. Fabrication then followed with higher temperature sensors made from (In, Sn) O2 (ITO) for evaluation up to 1000 degrees C. A patch antenna was modeled in ANSYS HFSS to operate in a high-frequency region (2.5-3.5 GHz) within a 50 x 50 mm2 confined geometric area using characteristic material properties. The sensor was fabricated on Al2O3 using screen printing methods and then sintered at 700 degrees C for Ag and 1200 degrees C for ITO in an ambient atmosphere. Sensors were evaluated at 600 degrees C for Ag and 1000 degrees C for ITO and analyzed at set interrogating distances up to 0.75 m using ultra-wideband slot antennas to collect scattering parameters. The sensitivity (average change in resonant frequency with respect to temperature) from 50 to 1000 degrees C was between 22 and 62 kHz/degrees C which decreased as interrogating distances reached 0.75 m.