Solution-processed dielectric films and Au RF antenna for temperature sensing

Sensing temperature is important for a wide variety of applications such as control systems and instrumentation which are integral to various industrial sectors and in research settings. To date, many prior studies have favored the use of the resistive thermistor approach given its simplicity. However, such devices are less sensitive to temperature changes compared to frequency-dependent approaches which are gaining momentum for detection. The importance of high sensitivity and reliable methods using a frequency-based approach for detecting temperature changes should thus be apparent, particularly if such sensors are also fabricated using low-cost approaches which are amenable toward miniaturized wireless platforms at the same time. In this study, Au rectangular single-arm spiral antennas with varying sizes were fabricated and RF S-parameter measurements were conducted over the frequency range of 300 kHz to 20 GHz. Solution-processed, two-dimensional (2D) hexagonal boron nitride (h-BN) was used with cyclohexanone and terpineol as solvents, and the films were characterized using dc current-voltage and frequency-dependent capacitance measurements. We also characterized our solution-processed h-BN films using Raman spectroscopy. The shift in the resonant frequency through the addition of h-BN over the underlying Au antenna was observed as this dielectric was coated on top of the antennas and the temperature response of the resonance frequency was measured. Alongside the experimental measurements, we also present results from our simulation analysis conducted using High Frequency Structure Simulator (HFSS) from ANSYS.