Underwater flexible shear-stress sensor skins

This paper reports the development of underwater flexible shear-stress sensor skins that enable not only the acquisition of shear-stress distributions on non-planar surfaces but also a reliable packaging scheme. The sensor skin fabrication consists of two steps: the fabrication of shear-stress sensors on silicon wafers and the fabrication of flexible skins by forming arrays of silicon islands sandwiched by two polyimide layers. The fabricated sensor skin has been packaged on a metal plug and bonding pads were folded to the back side through a slit on the plug. Wire bonding was performed on the back side to improve the reliability and minimize flow interference. The packaged sensor skin has been installed on a water tunnel and successfully tested.