Development and Performance Study of a Wireless Passive Temperature Sensor Based on Polymer-Derived Ceramic Composites-PZT Thin Film

This study presents a wireless, passive temperature sensor based on an LC resonant circuit. An interdigital capacitor (IDC) sensitive layer was fabricated by blending lead zirconium titanate (PZT) powder into a liquid-phase polymer-derived ceramics (PDC), forming a robust dielectric layer. Using HFSS simulations, the IDC structure and inductor dimensions were designed, and a theoretical resonant frequency was determined. Guided by these simulations, a flexible masking technique was employed to produce IDC electrodes on an alumina substrate. Leveraging the viscosity characteristics of the PDC solution, the sensitive layer was applied between the electrodes and subsequently crosslinked and pyrolyzed to form the capacitor. Wireless signal transmission was realized through electromagnetic induction, and the wireless response was collected via a network analyzer connected to a receiving inductor coil. The experimental results show that the thin-film sensor pyrolyzed at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$800~^{\circ }$ </tex-math></inline-formula>C exhibits superior dielectric properties and achieves the highest quality factor (Q-factor). As the temperature increases from room temperature to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$825~^{\circ }$ </tex-math></inline-formula>C, the resonant frequency decreases from about 5.6 MHz to approximately 4.8 MHz. Under these conditions, the sensor demonstrates a sensitivity of −0.439 kHz/°C.