0000000000773432
AUTHOR
R. Rix
Muscular MEMS—the engineering of liquid crystal elastomer actuators
A new class of soft-matter actuator, the liquid crystal elastomer (LCE), shows promise for application in a wide variety of mechanical microsystems. Frequently referred to as an 'artificial muscle', this family of materials exhibits large actuation stroke and generates considerable force, in a compact form which may easily be combined with the structures and devices commonly used in microsystems and MEMS. We show here how standard microfabrication techniques may be used to integrate LCEs into mechanical microsystems and present an in-depth analysis of their mechanical and actuation properties. Using an example from micro-optics and optical MEMS, we demonstrate that their performance and fle…
A thermotropic liquid crystal elastomer micro-actuator with integrated deformable micro-heater
We present a liquid crystal elastomer (LCE) actuator with large stroke and fast reaction time. LCEs show a large macroscopic shape change when heated above the phase transition (≈120°C). Buried wafer-level fabricated micro-heaters offer optimal thermal reaction times and compact design of the actuators. A relative length change of λ = 1.28 was obtained with 320 mW power consumption. Heating the device from room temperature takes τrise = 19.7 s, cooling below the phase transition temperature from the fully contracted state needs τfall - 5.6s. We verify that the displacement may be accurately controlled by varying electrical input power.
Iris-Like Tunable Aperture Employing Liquid-Crystal Elastomers
A liquid-crystal elastomer (LCE) iris inspired by the human eye is demonstrated. With integrated polyimide-based platinum heaters, the LCE material is thermally actuated. The radial contraction direction, similar to a mammalian iris, is imprinted to the LCE by a custom-designed magnetic field. Actuation of the device is reproducible over multiple cycles and controllable at intermediate contraction states.
Smart artificial muscle actuators: Liquid crystal elastomers with integrated temperature feedback
Abstract We present a smart, thermally stimulated liquid crystal elastomer actuator with an integrated heater and temperature sensor based on deformable polyimide wiring technology. Due to optimal thermal contact to the active material, heating from room temperature to the point of maximum contraction takes only 19.6 s; cooling requires only 5.6 s. The integrated temperature sensor allows closed-loop operation and characterize the thermomechanical properties of the material: open-loop positioning precision was found to be better than 45 μm and no inherent drift or hysteresis were observed. The maximum force generated by the actuator was 133 mN, corresponding to 76 kPa of stress. This ultra-…