Conformable, programmable and step-linear sensor array for large-range wind pressure measurement on curved surface

The wind pressure measurement, especially on curved surfaces is imperative in revealing flow characteristics. The flexible sensor with high linear sensitivity over large pressure range is still a significant challenge, especially for commutatively positive and negative pressure measurement. Here, we propose a conformable, range-programmable capacitive sensor that can extremely extend the measuring range but with high linear sensitivity. The key point is to precisely control the reference pressure of the flexible capacitive sensor array through microchannel network. The proposed sensor with reference pressure 0 kPa keeps stable at a highly-linear sensitivity of 0.28 kPa−1 in an initial measurement regime from 0 to 3 kPa, beyond which the linearity changes significantly. Via the tunable reference pressure, the linear ranges can be customized arbitrarily according to different flight conditions and measured positions, but without any deterioration of sensitivity. The theoretical model is built for the flexible capacitive sensor with tunable reference pressure, agreeing well with the experimental and finite element method results. Additionally, the bending effect is discovered when the flexible sensor is conformed on curved surfaces. This surface-mounted sensor skin is tested on a plate and is integrated with acquisition circuits on a standard airfoil NACA0012 in a wind tunnel and compares with the standard destructive method of pressure taps. It shows great potential applications in measuring wind pressure on curved surfaces, such as for “Fly-by-Feel” of unmanned aerial vehicles and wind tunnel test.