Design and performance analysis of a novel displacement-based temperature sensor

In this paper, we present a proof-of-concept for a novel temperature sensing approach that combines the thermal expansion and a compliant mechanism. The objective is first to demonstrate its feasibility at the macroscale, develop and validate an FEM model at the macroscale and then scale down the FEM model to verify the possible implementation of the mechanism at the microscale. The sensing approach relies on a mechanical compliant mechanism that amplifies the thermal expansion of a structure. A testing platform equipped with an IR thermometer, thermocouple, a power supply, and laser distance sensors, is implemented to demonstrate the operability of the proposed sensing mechanism. A numerical model of the sensor is developed using the FE software Ansys. The numerical results show a good agreement with their experimental counterparts at the macro scale. The model is then used to numerically investigate several configurations, namely single, double, triple and quadruple compliant mechanisms. The amplification factor is found the highest when using the double compliant mechanism. A temperature sensitivity of 28.5 μm/°C is achieved for this compliant mechanism. The numerical analysis also demonstrated that the performance obtained at the macro scale, can be conserved for microscale devices. However, buckling of some elements is observed for the microscale system which degrades the performance of the sensor when subjected to relatively large displacements. The microscale FEM model shows the possible prevention of buckling issues by slightly modifying the geometry of the compliant mechanisms. The present study is expected to provide baseline and guidance for the implementation of the sensing approach for MEMS devices.