Temperature Resolution Analysis of Resonant MEMS Temperature Sensor Based on Quality Factor Optimization

The TianQin mission, as a space-based gravitational wave detection, aims to establish a gravitational wave observation window in the megahertz (mHz) frequency band. The temperature control for the core payload in this context demands extreme precision, needing to be better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu $ </tex-math></inline-formula>K/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup>. Compared to resistive and optical temperature sensors, resonant MEMS temperature sensors (RMTSs) offer advantages such as small-size, low-power consumption, and dense integration. However, existing works hitherto indicate that RMTS need further enhancement in temperature resolution to meet this requirement. This study proposes an optimization approach for the temperature resolution of RMTS by quality factor optimization of a double-ended tuning fork (DETF) resonant structure. A theoretical modeling of RMTS incorporated with frequency noise analysis and amalgamated a temperature sensitivity simulation render an accurate analytical model for the temperature resolution of RMTS. Further analysis and optimization of the quality factor are conducted encompassing the relationship between mechanical thermal noise and quality factor. Moreover, the frequency background noise and temperature resolution of the optimized RMTS with respect to variations of geometric parameters of the resonant structures were evaluated, in terms of quality factor and resonant frequency ratios. Compared to RMTS without optimization, the frequency background noise of optimized RMTS is reduced by up to 7.35 times, whereby in the frequency range of 0.1 mHz–1 Hz, the temperature resolution is better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu $ </tex-math></inline-formula>K/Hz<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup>. Additionally, noise suppression and sensitivity enhancement strategies in this study can also be applied to other types of resonant sensors.