DESIGN AND FABRICATION OF COMPLIANT MICROMECHANISMS AND STRUCTURES WITH NEGATIVE POISSONS RATIO

This paper describes a new way to design and fabricate compliant micro mechanisms and material structures with negative Poisson's ratio (NPR) . The design of compliant mechanisms and material structures is accomp lished in an automated way using a numerical topology optimization met hod. The procedure allows the user to specify the elastic properties o f materials or the mechanical advantages (MA's) or geometrical advanta ges (GA's) of compliant mechanisms and returns the optimal structures. The topologies obtained by the numerical procedure require practicall y no interaction by the engineer before they can be transferred to the fabrication unit. Fabrication is carried out by patterning a sputtere d silicon on a plasma-enhanced chemical vapor deposition (PECVD) glass with a laser micromachining setup. Subsequently, the structures are e tched into the underlying PECVD glass, and the glass is underetched, a n in one two-step reactive ion etching (RIE) process. The components a re tested using a probe placed on an x-y stage. This fast prototyping allows newly developed topologies to be fabricated and tested within t he same day. [188]