TU Delft researchers develop algae-powered soft robot arm

Researchers at TU Delft have developed a flexible, soft robot arm that operates without mechanical motors, hydraulics, or compressed air. The proof-of-concept consists of a small strip, approximately two centimeters long and one millimeter thick, composed of two different hydrogel layers containing microalgae.

The device is powered by the natural metabolism of the algae. When exposed to light, the algae perform photosynthesis, converting CO2 into sugars and absorbing nitrogen. This process alters the pH level of the hydrogel. Because the two layers react differently to these pH changes, they swell at different rates, causing the strip to bend. When the light is removed, the algae consume the stored sugars and release CO2, lowering the pH and causing the actuator to bend in the opposite direction within ten seconds.

Lead researcher Marie-Eve Aubin-Tam and PhD candidate Fan Jiang noted that the technology could be particularly useful for delicate tasks in underwater environments, such as picking up and moving small, fragile objects. The microalgae act as a largely self-sufficient energy source.