A multi-step DRIE process for a 128 × 128 micromirror array
ABSTRACT A multi-step DRIE process for fabricating a vertical comb-driven micromirror array with five different heights was developed. This process was used to fabricate a dual-axis 128 × 128 micromirror array with a high resonance frequency.
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ABSTRACT: Polymers can be used to constitute "artificial muscles" that actuate under an electric stimulus. These polymers include dielectric elastomers and thermally expandable polymers. They are insulating and relatively compliant. Their electric activation is enabled with integration of electrodes, heat conductors or heaters. However, the electrodes or heaters are stiff and inevitably restrain actuation of the polymers. Confinement effects on the polymers need to be clarified before the polymers are effectively exploited as actuation materials. The present theoretical and numerical study suggests that the constrained thermal expansion delivers more powerful actuation than the constrained dielectric elastomer does. Understanding of the confinement effects motivates development of various layout designs of the embedded electrode, heaters or skeletons for the compliant polymers. However, fabrication of the micro-actuators using a thermally expandable polymer is more successful than that using a dielectric elastomer. Based on the present research, a new class of polymer thermal micro-actuators with embedded heat conductors (or skeletons, in the other words) is developed. This actuator design features an adequate actuation strain, a large actuation stress, high work energy density and improved heat transfer. It outperforms many other thermal actuator designs based on either pure polymers or silicon. Various layout designs of heaters and skeletons are developed for thermally expandable polymers. These include meandering skeletons of symmetric, asymmetric and V- shapes. Polymer actuators with the different skeleton layout could deliver varying characteristics of motion and force. The generated motion can be rectilinear, curvilinear, in-plane or out-of-plane. The design embodiments confirm that the confined thermally expandable polymers are effective for actuation.
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ABSTRACT: This paper presents pull-in analysis of torsional MEMS scanners actuated by electrostatic vertical combdrives with general comb gap arrangements and cross sections. The analysis is based on a 2-DOF actuator with a single voltage control. Three failure modes of the scanners are identified as in-plane twist, transversal motion, and out-of-plane twist. For each failure mode, analytical expressions of pull-in deflection are obtained by applying 2D analytical capacitance models to the derived pull-in equations. From these, the dominant pull-in mechanism is shown to be in-plane twist for scanners with high-aspect-ratio torsional springs. The analytical calculations for both symmetric and asymmetric capacitances are shown to be in good agreement with simulation results. The optimum scanner design is achieved when the pull-in deflection matches the capacitance maximum angle. The condition can be expressed in terms of the ratio of the comb thickness to the comb gap, which is smaller than the typical aspect ratio of deep reactive ion etching. The optimum tradeoff between the maximum deflection angle and the number of movable combs is achieved by adjusting the overlap of the movable and fixed combs and the distance of the comb sets from the axis of the rotation.Journal of Microelectromechanical Systems 11/2008; DOI:10.1109/JMEMS.2008.2004824 · 1.92 Impact Factor
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ABSTRACT: The intensive investment in optical microelectromechanical systems (MEMS) in the last decade has led to many successful components that satisfy the requirements of lightwave communication networks. In this paper, we review the current state of the art of MEMS devices and subsystems for lightwave communication applications. Depending on the design, these components can either be broadband (wavelength independent) or wavelength selective. Broadband devices include optical switches, crossconnects, optical attenuators, and data modulators, while wavelength-selective components encompass wavelength add/drop multiplexers, wavelength-selective switches and crossconnects, spectral equalizers, dispersion compensators, spectrometers, and tunable lasers. Integration of MEMS and planar lightwave circuits, microresonators, and photonic crystals could lead to further reduction in size and costJournal of Lightwave Technology 01/2007; 24(12-24):4433 - 4454. DOI:10.1109/JLT.2006.886405 · 2.86 Impact Factor