科研之友
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摘要
We studied the mechanical bistability of strained metal/oxide microstructures that were released from the substrate except at a central attachment point. The devices' planar layout was symmetric, but the symmetry was broken when the structures were released from the substrate. Residual stress caused each structure to curl up from the substrate along one of two 90A degrees axes. This configuration suggested that the structures could be bistable as long as there was not plastic deformation-but only by completely flattening, constraining and re-releasing the device. We investigated other switching paths by simulation and experiment. Finite element modelling in ANSYS showed that the device could be reversibly switched between shapes by applying a single point force. Experiments showed that reversible, repeatable switching could also be achieved by the distributed force of gas flow in the plane of the substrate, with larger devices switching at slower flow velocities. Experimentally characterized devices with edge lengths between 700 and 550 microns showed switching in the airflow velocity range of 2-5 m/s, with the threshold flow rate governed by the height and projected area of the device. These bistable surface-machined microdevices could serve as mechanical memory cells, passive threshold sensors, and archivers of peak flow events.
- 出版日期2017-7
