Spectral Analysis and Characterization of a Membrane-Based Artificial Hair Cell Sensor

A fully hydrogel-supported, artificial hair cell (AHC) sensor based on bilayer membrane mechanotransduction is designed with sensitivity and versatility in mind. Thanks to fabrication improvements from previous generations, the sensor demonstrates peak current outputs in the nanoamp range and can clearly measure inputs as high as 2k Hz. Characterization of the AHC response to base excitation and air pulses show that membrane current oscillates with the first three bending modes of the hair. Output magnitudes reflect of vibrations near the base of the hair. A 2 DOF Rayleigh-Ritz approximation of the system dynamics yields estimates of 19 N/m and 0.0011 Nm/rad for the equivalent linear and torsional stiffness of the hair’s hydrogel base, although double modes suggest non-symmetry in the gel’s linear stiffness. The sensor output scales linearly with applied voltage (1.79 pA/V), avoiding a higher-order dependence on electrowetting effects. The free vibration amplitude of the sensor also increases in a linear fashion with applied airflow pressure (18.4 pA/psi). Based on these sensitivity characteristics, an array sensing strategy for these sensors is proposed.