Travelling Light

Sluicing around our circulatory systems, drug molecules eventually end up where they’re needed but they’re also prone to the swirling currents around organs and tissues. The answer may be tiny soft robots, artificial devices designed to swim through pulsing fluids or gently sway molecules to where they need to be. Surrounded by water, this tiny gear (10 million times smaller than a windmill in a sandcastle) spins anticlockwise after a blast of green laser light and clockwise with red light. Different areas on the gear’s blades heat up in the changing wavelengths, producing a turning force by a process known as the Marangoni effect. Elsewhere, researchers use similar tricks of light to steer devices around corners – prototypes for tiny 'freighters' that may one day deliver chemical cargos to specific destinations around the body.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video by Kai Hou and colleagues
• Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing P. R. China
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY-NC 4.0)
• Published in Science Advances, September 2021