| Microactuators are the essential parts for microelectromechanical systems (MEMS) that require movable components. The widely used electrostatic comb-drive actuators are limited to only a few microns of travel. Actuators with larger travel range capability are desirable in optical applications. Many types of mechanical power transmission mechanisms for long-range driving purposes have been reported. In general, they can be categorized into walking actuation, orthogonal coupling actuation, impact actuation, and clamp-and-pull actuation. The travel range of these microactuators is extended to tens of microns, or even hundreds of microns. However, most of these devices require not only relatively large footprint (>1mm2) but also large driving voltages (10's of volts to more than 100 volts). Moreover, either two sets of actuators or complicated phase-matching operation is required for those to have a bi-directional actuation capability. Complex driving mechanisms also pose serious stability and reliability problems. These drawbacks hinder them from being employed, in particular, in high device density arrays systems, such as a fiber-optic switch matrix.; We have developed a novel polysilicon surface-micromachined electro-thermal vibromotor that is capable of bi-directional travel, long-range and fast speed actuation. With features like CMOS-compatible driving voltages and small footprint, it is especially suitable for arrayed applications. The electro-thermal vibromotor is a slider-based device. Mechanical forces are transferred to the slider through contact friction from the vibrating thermal actuators on the sides. The contact condition can be controlled through input drive voltages or frequencies, which results in two modes of operation—push mode and pull mode, which allows the slider to move in opposite directions. Push mode has finer step size that is suitable for position-tuning applications, while pull mode has faster actuation speed that is desirable in switching applications.; Through modeling and characterization, better device performance for specific applications has been achieved with optimized device designs and operation methods. We have demonstrated three different devices based on the electro-thermal vibromotor, including a fiber-optic shutter switch, a large optical switch matrix, and a tunable wavelength filter. An actuation speed as high as 15.6 mm/s has been demonstrated with 10.5V, 20kHz drive signal. Stable and repeatable switching actuation was demonstrated with 15% duty-cycle pulsed drive signal. |
