Active Artificial Hair Cells for Use in Fluid Environments

Artificial hair cells (AHCs) are sensors inspired by biological hair cells. These devices often have lower sensitivities and poorer frequency resolutions than their biological counterparts. This is especially true when AHCs are placed in fluid. In the authors’ previous work, active AHCs were developed which used nonlinear feedback control to mimic the cochlea’s nonlinear amplifier. Incorporating this nonlinear control law can improve the AHC’s sensitivity, frequency selectivity, and dynamic range. This work examines an active artificial hair cell partially submerged in water. The fluid loading on the sensor adds inertia and significantly increases damping. A model of the sensor in air is developed and then modified to incorporate the added inertia and damping from the fluid. Simulation and experimental results show that the active artificial hair cell can overcome the added fluid inertia and damping to amplify oscillations due to low input levels and create a sharper frequency response. The resulting sensor is better suited to operate in fluid environments for flow sensing than an otherwise passive device. These sensors could potentially develop into replacements for damaged hair cells in the fluid-filled cochlea.