Resonant Spiral Micromachined Structure and the Effects of a Curved Geometry

This paper reports on an innovative double anchored silicon beam covered with an Aluminum Nitride (AIN) piezoelectric layer and shaped as an Archimedean spiral. The spiral is an alternative to a long double-arm cantilever with conjoint ends. A simplified analytical model is compared to a finite element model and results show a difference between the fundamental resonance frequencies. This difference is further analyzed by comparing the spiral to a double arm cantilever connected at its end. Besides being much more compact, its multiple curvatures increase the natural resonant frequency when compared to a cantilever.