Technology for fabricating dense 3-D microstructure arrays for biomimetic hair-like sensors

This paper reports high-density arrays of 3-dimensional (3-D) high-aspect ratio MEMS structures that can imitate biological hairs. Hair has many properties, including high aspect ratio (long and small footprint), large surface area, mechanical flexibility and robustness, and customized material properties. Hair sensors can be made in large arrays, provide high sensitivity through local neural processing, and offer a multiplicity of functions. In nature, hairs typically exist in large-scale arrays, offering distributed sensing functions, redundancy, and improved stability, sensitivity, and dynamic range. In this paper, we present a fabrication technology for forming highly dense 3-D arrays of microstructures useful for a variety of sensing applications, which realize some of these biological advantages. We have fabricated 4×4, 5×5, and 10×10 accelerometer arrays, achieving a sensor density of ~100 sensors/mm². Initial testing shows accelerometer resonant frequencies and static capacitance values that vary with proof mass and hair/spring dimensions as expected.