Wireless Passive Temperature Sensors Using Integrated Cylindrical Resonator/Antenna for Harsh-Environment Applications

Wireless passive temperature sensors for harsh-environment applications based on cylindrical microwave cavity resonators are presented herein. Slot antennas are integrated with sensors with zero additional volume. The resonant frequencies of the sensors are determined by the dielectric constants of the ceramic materials, which monotonically increase versus temperature. Silicoboron carbonitride (SiBCN) ceramic materials, which are very robust inside harsh environments featuring high temperatures and corrosive gases, are optimized in this paper to reduce dielectric losses and increase sensing ranges and accuracies. A robust interrogation antenna is developed to wirelessly measure the sensors up to 1300 °C. Two sensors based on Si₆B₁ and Si₄B₁ ceramics are measured up to 1050 °C and 1300 °C, respectively, with a sensitivity of ~0.78 MHz/°C at 1050 °C. This type of wireless, passive, and robust sensor can be used for many harsh-environment applications, such as gas turbines.