Parylene-coated bioinspired artificial hair cell for liquid flow sensing

In this work we report the design and development of a biomimetic waterproof Si/SiN multilayered cantilever whose internal stress gradient bends the beam out of the plane enabling flow velocity detection in water. A water resistant parylene conformal coating has been deposited on the artificial hair cell for waterproof operation. The sensing mechanism is represented by a piezoresistive strain-gauge along the cantilever beam. A set-up for analysing sensor responsivity in air and water has been used and its electrical behavior is reported. Responsivity of 0.7 mV/(cm/s) is recorded and a linear response of sensor read-out signal amplitude with respect to flow pulses up to 30 Hz. Parylene conformal coating is demonstrated to be an efficient method for water sealing and can be effective in the post-fabrication for tuning the micromechanical cantilever properties