Fabrication of biomimetic 3-D structured diaphragms

Abstract

We report on a new approach to the fabrication of 3-D structured diaphragms using integrated surface and deep reactive ion etching (DRIE) bulk silicon micromachining on a silicon-on-insulator (SOI) wafer. Polysilicon diaphragms of 1 mm × 2 mm × 1.2 μm, and 1 mm × 2 mm × 2.4 μm parylene diaphragms, which are designed for a biomimetic directional microphone and a differential microphone, respectively have been successfully fabricated by our method. The membranes have 20 μm-thick silicon proof masses, solid stiffeners, hollow stiffeners, and 20 μm-deep corrugations to mimic the tympanal membranes of the fly's ears. Acoustic measurements of the diaphragm using laser vibrometry have demonstrated high directional sensitivity of the device.