A Flexible Flow Sensor for Detecting Airflow Velocity and Incident Angle

A flexible flow sensor is proposed to measure the airflow velocity and incident angle. The sensor consists of a polyimide (PI) substrate, a flat cantilever beam and a graphene piezoresistor. The cantilever beam deforms under the action of fluid-structure interaction (FSI), resulting in changes in the resistance of the graphene piezoresistor. The piezoresistor was prepared by spraying coating of graphene inks using a patterned parylene mask and then encapsulated by coating another polyimide layer to form a sandwiched structure. Experimental results indicate that the flow sensor has a wide detection range of flow velocity (0-30 m/s) and incident angle (0-25°), with a high resolution of 0.94 m/s and 0.23°, respectively. Compared with curved cantilever, the flat cantilever achieves higher sensitivity to the incident angle, and smaller disturbance to the flow field. The arrangement of the flow sensors on an airfoil is discussed for estimation of flight parameters.