Light‐Driven Gripper Grown on Optical Fibers

Researchers at the Faculty of Physics, University of Warsaw, used the liquid crystal elastomer technology to demons­trate a series of micro-tools grown on optical fibers. The 200-micro­meter gripers are controlled remotely, without electric wiring or pneu­matic tubing, with green light delivered through the fibers – absorbed light energy is directly converted into the gripper jaws’ action.

The optical pliers next to the mandibles of a Formica polyctena ant for comparison. (Source: UW Physics)

Gripping objects is a funda­mental skill for living organisms, from the micro­scopic rotifers, through the amazing dexterity of the human hand, to the jaws of predatory whales and soft tentacles of giant squids, and is also vital for many ever-shrinking techno­logies. Mechanical grippers, powered by electric, pneumatic, hydraulic or piezo­electric servos, are used at scales down to millimeters, but their com­plexity and need for force trans­mission prevent minia­turization. The researchers together with colleagues from the AGH University of Science and Techno­logy in Cracow, Poland, have now used liquid crystal elastomer micro­structures that can change shape in response to light to build a light-powered micro-tool – optical pliers. The device was built by growing two bending jaws on the tips of hair-sized optical fibers.

Liquid Crystalline Elastomers (LCEs) are smart materials that can reversibly change shape under illu­mination with visible light. In their proto­type, scientists combined the light-powered LCEs with a novel method of fabri­cating micro­meter-scale structures: when UV light is sent through the optical fiber, a cone-shaped structure grows at the fiber tip. The light-induced mechanical response of thus grown micro-structure depends on the orienta­tion of mole­cules inside the elastomer element and can be controlled to get bending or contrac­ting micro-actuators. The new elastomer growth technique readily offers a variety of micrometer-scale, remotely controlled func­tional structures – building blocks for the micro-toolbox. (Source: U. Warsaw)

Reference: M. Zmyślony et al.: Optical Pliers: Micrometer‐Scale, Light‐Driven Tools Grown on Optical Fibers, Adv. Mat., online 6 July 2020; DOI: 10.1002/adma.202002779

Link: Photonic Nanostructure Facility, Faculty of Physics, University of Warsaw, Warsaw, Poland

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