Dual-Mode Thermal-Piezoresistive Coupled Resonators for Fast and Stable NIR Measurements With Differential Output

This study reports a resonant Near-Infrared (NIR) detector based on dual-mode, self-oscillating Thermal-Piezoresistive Coupled Resonators. The resented device alleviates the current trade-offs between resolution and response time in Microelectromechanical Systems (MEMS) thermal detectors. The thermal-piezoresistive coupled resonators operate simultaneously in the in-phase and out-of-phase modes and the frequency difference between two modes is selected as the output metric. The square-shaped coupling area of the coupled resonators acted as the NIR sensing region because of its low thermal resistance. Our design demonstrated a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$700~\mu {s}$ </tex-math></inline-formula> response time, achieving 700-fold improvement compared to the conventional single-frequency output methods. Further, the differential output method inherently compensates for temperature drift, significantly increasing the immunity of device to thermal crosstalk by a factor of 25. A noise equivalent power density resolution of 253 pW/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sqrt {\textit {Hz}}$ </tex-math></inline-formula> is achieved.