Liquid Crystal Elastomer Based Thermal Microactuators and Photothermal Microgrippers Using Lateral Bending Beams

The remarkable properties of liquid crystal elastomers (LCE) for spatially controlled actuation are utilized to perform complex tasks such as to mimic versatile motion of living organisms and cilia in soft robotics. As opposed to the common out-of-plane bending in flat LCE films, many planar micro-electro-mechanical and microfluidic systems typically operate based on the lateral movement of the functional parts. The challenge of implementing the in-plane bending of LCE actuators is often associated with the limited capability for miniaturization of the existing techniques, along with the requirement for post-fabrication assembly. In this paper a method for fabrication of thermally actuated LCE beams for in-plane bending applications, which is based on direct laser writing and micromolding is reported. Mesogenic alignment is modified near the sidewalls of the channel structures patterned with vertical microgrooves. The method allows monolithic fabrication of LCE-based microgrippers for micromanipulation and microassembly applications in life sciences and in manufacture of microsystems. It is shown that the photothermally driven microgrippers can perform soft grasping of micro-objects, providing large gripping strokes with relatively low actuation stimuli. The fabrication method offers more design opportunities for LCE-based microactuators and a useful route toward realization of gripping and cargo transportation functionality in microrobotics.