High-Sensitivity Thermal Sensing Based on a Single Strain-Assisted Resonator

Microresonator-based temperature sensors offer stable and high-resolution temperature detection. However, typical temperature-sensing techniques based on resonators suffer from design complexity and low sensitivity. In this study, we present a simple high-sensitivity temperature sensor that comprises a sealed electrostatically actuated clamped–clamped silicon microbeam resonator. The sensor’s high sensitivity is attributed to the thermal-strain effects due to the mismatch between the thermal expansion coefficients of the composite materials. And the sensitivity is further enhanced by operating the resonator near the buckling zone via in situ Joule heating. In addition, The sensor operates at a single drive frequency that corresponds to the resonant frequency at the maximum temperature. A change in temperature induces a thermal strain that shifts the resonant frequency, which changes the output voltage. This considerably simplifies the readout system from the typical frequency-tracking method to the proposed amplitude tracking method. The encapsulated sensor achieves a minimum detectable temperature of 0.0196 °C and an absolute temperature coefficient of frequency of 1757 ppm/°C. These results demonstrate the great potential of the proposed sensor for efficient resonant thermal sensing with high resolution, enhanced sensitivity and a simplified readout scheme.