Modeling, Design, Fabrication, and Demonstration of a Digital Micromirror With Interdigitated Cantilevers

We present the modeling, design, fabrication, and measurement results of a novel digital micromirror based on a new actuator called interdigitated cantilevers. In contrast to conventional micromirrors that rotate through the twisting actuation of a hinge, this micromirror has a symmetric bidirectional rotation through a bending actuation of interdigitated cantilevers hidden under a mirror plate. For the static and dynamic characteristics of the proposed micromirror, analytical models were developed first on the basis of the Euler-Bernoulli beam equation, as well as both distributed and lumped-parameter models. The results of the developed analytical models are in good agreement with those of a finite-element-method (FEM) simulation, having just a 10% deviation. On the basis of these analytical models, we successfully designed, fabricated, and evaluated a micromirror with a mirror size of 16 mum times 16 mum. The fabricated micromirror has a mechanical rotation angle of plusmn10deg, a pull-in voltage of 54 V, a resonant frequency of 350 kHz, and a switching response time of 17 mus. The measurement results compare favorably with those of analytical models and FEM simulations, with deviations of less than 15% and 10%, respectively.