Investigation of geometric parameters on the performance of MEMS calorimetric wall shear stress sensors using numerical and experimental approaches

Fluid flow over surfaces is a fundamental phenomenon in various engineering applications, where the determination of wall shear stress plays a crucial role. Calorimetric wall shear stress sensors, based on micro-electromechanical systems (MEMS) technology, offer promising solutions for wall flow conditions due to their ability to detect flow direction and fluctuations in wall shear stress with high temporal resolution. This paper presents a comprehensive investigation into the influence of geometric parameters on the performance of calorimetric wall shear stress sensors. Both experimental and numerical methodologies are employed to explore parameters such as the distance between detectors and heaters and the size of the cavity. Numerical simulations demonstrate the effects of inter-beam distance on measurement range and sensitivity, highlighting trade-offs between enhanced range and potential sensitivity compromise. Additionally, the influence of cavity size, particularly depth, on sensor sensitivity is elucidated, with optimal sensitivity observed at depths exceeding 100 µm. Experimental studies corroborate numerical findings, providing valuable insights into practical sensor behavior. Furthermore, the study compares sensors with different cavity shapes, offering insights for sensor design and fabrication. Overall, this investigation enhances our understanding of calorimetric wall shear stress sensors and their potential applications in engineering contexts, guiding future research and development efforts in sensor technology.