Researchers at the University of Warsaw Faculty of Physics have used liquid crystal elastomer (LCE) technology to develop a bioinspired micro-robot that mimics the gait of a caterpillar to climb slopes, squeeze through slits and transport loads. The 15-millimeter-long soft robot harvests energy from green light and is controlled by a spatially modulated laser beam.

The 15-millimeter-long robot harvests energy from green light. Image source: University of Warsaw Faculty of Physics.The 15-millimeter-long robot harvests energy from green light. Image source: University of Warsaw Faculty of Physics.For decades, scientists and engineers have worked to build robots mimicking different modes of locomotion found in nature. Most of these designs have had rigid skeletons and joints driven by electric or pneumatic actuators.

In nature, however, many creatures with soft bodies—earthworms, snails and larval insects—can move in complex environments using different strategies. Up-to-date attempts to create soft robots that imitate the movements of these animals have been larger scale (typically, tens of centimeters), mainly due to difficulties in power management and remote control.

Using LCEs—smart materials that can exhibit large shape change under illumination with visible light—it is now possible to pattern these soft materials into three-dimensional forms with a pre-defined actuation performance. The light-induced deformation allows an LCE structure to perform complex actions without numerous discrete actuators.

The University of Warsaw researchers—led by Piotr Wasylczyk, head of the Photonic Nanostructure Facility, together with colleagues from LENS Institute, in Florence, and the University of Cambridge—developed the natural-scale soft caterpillar robot with an opto-mechanical LCE monolithic design. The robot body is made of a light-sensitive elastomer stripe with patterned molecular alignment. By controlling the traveling deformation pattern, it mimics the gait of the caterpillar.

According to the researchers, designing soft robots calls for new paradigms in mechanics, power supply and control. Rethinking materials, fabrication techniques and design strategies could open up new areas of soft robotics in micro- and millimeter-length scales, including swimmers (both on-surface and underwater) and even flying robots.

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