Bimaterial electromechanical systems for a biomimetical acoustic sensor

Abstract

Full-field optical measurement of curvatures in ultra-thin-film-substrate systems in the range of geometrically nonlinear deformations Bimaterial planarized micromechanical beams have been designed, simulated, and fabricated with lengths in the range 800-5800 lm and distance to substrate 0.8-4.0 lm. The beams are to be used as vertical-mode resonant gates on p-type field-effect transistors for implementing an adaptable MEMS acoustic sensor inspired by the human ear. A process for fabricating planar bilayer double-clamped beams made of silicon nitride (SiN) and aluminum (Al(1%Si)) has been developed. The planar design and bimaterial approach allow the fabrication of relatively straight beams with length up to 5800 lm with the possibility of controlling the degree of static deflection of the beams. The fabricated beams have shown a maximum deflection of $300 nm and a transverse concave shape with respect to the substrate due to the bilayer nature of the structure. From wafer curvature measurements, the stress in the SiN and Al(1%Si) is 200 and 280 MPa, respectively. Finite element simulations and analysis of the profile of the beams have demonstrated that the films' stress magnitude influences the longitudinal and transverse profile of the beams. The fabricated devices resonate mechanically in the range 15-160 kHz. Preliminary electrical characterization of the devices has shown drain currents in the lA range for gate voltages of À20 to À25 V and drain voltages of À5

Design principles of hair-like structures as biological machines

“…Three states are possible depending on the external force applied and the effective stiffness of the system: hair bundles may be monostable, bistable switches or may spontaneously oscillate [44]. The transduction mechanism of stereocilia has inspired a range of cantilever-based acoustic sensors with aspect ratios of up to 700 to enhance sensitivity [45][46][47][48][49][50].…”

MEMS design and modelling based on resonant gate transistor for cochlear biomimetical application

“…High frequency detection Low frequency detection Mastropaolo et al 2012;Wang et al 2012). In this paper, the mathematical model of RGT device employed in cochlear model has been developed.…”

Toward a neuromorphic microphone

“…Conceptually, beams would vibrate at a range of frequencies, and RGFETs would be placed to pick up this vibration and amplify it (see Koickal et al, 2011 ). It proved difficult to integrate the technologies although advances were made in the creation of long narrow beams (as discussed in Mastropaolo et al, 2012 ). It appeared that the stiffness of the beams, and tension in them after manufacture meant that driving the system acoustically to create measurable results proved impossible.…”