These Robotic Arms Are Powered by Algae. Watch How They Move

Researchers at Delft University of Technology have built tiny soft robotic arms that bend when algae on their surface photosynthesise. The work explores how living cells can be integrated into functional materials, and could inform soft robots that respond to their surroundings while using little external energy.

The arms, about three-quarters of an inch long and as thick as a credit card, use two hydrogel layers; algae-driven changes in local acidity make one layer swell or shrink, causing the arm to bend. Light triggers the process, but significant movement takes hours. Demonstrations included a four-fingered gripper lifting a hollow metal sphere and a hook picking up a rubber ring, both very light objects. The algae need no genetic modification, and potential future uses include agricultural equipment, lab fluid control and underwater robotics.