An Ultrathin and Fast Response Flexible Shear Stress Sensor With Improved Thermal Efficiency

In this letter, we introduce an ultrathin flexible shear stress (FSS) sensor with improved thermal efficiency by suspending the fabricated sensor on a flexible Polyimide (PI) substrate. Remarkably, through a dedicated microelectromechanical system fabrication process, the thickness of the proposed FSS sensor film is reduced to an ultrathin level of 6 μm. Consequently, the suspended FSS sensor can overheat by 25 °C with just 9 mW of heating power, leading to a 134% enhancement in thermal efficiency compared to the nonsuspended counterpart. When the FSS sensor is configured in a 50 °C constant temperature mode, it exhibits a prominent sensitivity of 1.99 V
²
/Pa
^1/3
within the input shear stress of 0–2.5 Pa, while its heating power is less than 17 mW. In addition, the square and sinusoidal wave testing indicates that the configured sensor system has a fast response time of 1.2 ms and a bandwidth of 630 Hz. Moreover, the impact of tilt angle on sensor output was examined both theoretically and experimentally, revealing a strong similarity between the results. This suggests that the proposed sensor holds promise for applications in fluid dynamics and aerodynamics.