All-Ceramic LC Resonator for Chipless Temperature Sensing Within High Temperature Systems

The primary focus of this work is to fabricate and evaluate electroceramic based LC resonators for wireless sensing at high temperatures. An all-ceramic planar LC resonator was fabricated on a polycrystalline Al
₂
O
₃
substrate by using tin-doped indium oxide (ITO) as the electrode material. The LC resonators were deposited on the substrate by a novel two-step micro-casting technique. The resonator was designed using the ANSYS Maxwell package to operate within a wide frequency bandwidth from 10 to 80 MHz. A similar all-ceramic inductor was fabricated and used as the interrogator antenna to collect the wireless response at high operating temperature. The wireless characterization was performed by a radio frequency (RF) signal generator and an
in-situ
spectrum analyzer from 500 - 1200°C. The microstructural, chemical, and electrical stability of the LC resonator was investigated by SEM, 4-point conductivity, and XRD. Additionally, a robust adaptive signal processing algorithm was developed to analyze the wireless response of multiple LC resonator. The adaptive algorithm developed in this work is data driven and does not require a predefined model to analyze the wireless response from the LC resonator.