Smart artificial muscle actuators: Liquid crystal elastomers with integrated temperature feedback

• Thermotropic liquid crystal elastomer actuators. Integrated deformable wiring (Pt heater and sensor).
• Temperature sensors allows for closed loop control.
• Fast response (19.6 s from room temperature); high stroke (30%).
• Moderate generated force (133 mN). 45μm open loop precision at the edge of the phase transition.
• Hysteresis- and drift free operation.

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-compact actuator with integrated feedback is useful in applications that require large stroke in confined space.