Study on Developing Micro-Scale Artificial Hair Cells

Abstract

The cochlea, in the mammalian inner ear, transduces acoustic waves into electrical signals that are transmitted to the brain. One of the critical functions of the cochlea is its biological nonlinear behavior that amplifies faint sounds and compresses high sound levels. Previously, authors mimicked the aforementioned nonlinear characteristics in piezoelectric augmented structural cantilevers through nonlinear feedback controllers. The present effort is a continuation of the previous studies in the development of micro-electro-mechanical system (MEMS) scale artificial hair cells (AHCs).

The current research investigates the potential of transforming MEMS scale cantilevers, initially designed for use as scanning thermal microscopy probes, into micro-scale artificial hair cells. These cantilever structures are fabricated by employing electron beam- and photo-lithography, together with Low Pressure Chemical Vapor Deposition (LPCVD), metal evaporation, dry- and wet-etching on n-type silicon wafer substrates. In this work, dynamic characterization of these micro-structures is the focus. A series of dynamic tests are conducted on the MEMS micro-structure as it is subjected to base excitation. The dynamic characteristics of the MEMS system are investigated by varying the excitation levels and evaluating the limits of the structure’s linearity. Based on the experimental findings the potential of using these MEMS cantilevers as active artificial hair cells is evaluated.