This paper describes the development of a capacitive wall shear stress sensor capable of measuring time-resolved skin friction in a two-dimensional plane. The differential microelectromechanical systems-based sensor features a 1 mm by 1 mm floating element on a 7 mm circular die. This proof-of-concept device utilizes backside wire bonds instead of through-silicon-vias or frontside wire bonds to minimize surface roughness. A modulation/demodulation scheme is incorporated to measure mean and fluctuating wall shear stress in both planar directions. Average sensitivities of 1.22 mV/Pa and 1.76 mV/Pa are found at 1 kHz for the x- and-y axes, respectively.
