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

Robotic grippers can now pick up and manipulate objects using only light as an energy source.

Researchers at Delft University of Technology have developed soft robotic arms that move using algae. These bioactuators, about three-quarters of an inch long, consist of two hydrogel layers colonized by algae. The algae's photosynthetic activity, driven by light, alters the local pH, causing one hydrogel layer to swell or shrink. This differential change in volume controls the bending of the robotic arm. Specifically, algae absorb carbon dioxide and fix nitrogen during photosynthesis, making the environment more basic, which causes the hydrogel to swell significantly. When it's dark, algae respire, releasing carbon dioxide, returning the pH to acidic levels and causing the hydrogel to shrink. This pH-responsive mechanism allows for controlled movement. The team demonstrated a four-fingered gripper that closes under light and a hook-shaped gripper that can pick up small objects. These algae-powered robots require only light as an external energy source and possess minimal environmental impact.

This development signals a new direction in soft robotics, moving towards bio-integrated systems that leverage natural processes for actuation. The algae's ability to autonomously respond to light by altering their local environment offers a pathway for self-sustaining and minimally invasive robotic components. The localized effect of the algae's metabolic processes means these bioactuators could be suitable for applications where precise control with minimal disruption is key, such as in sensitive environments or intricate machinery.

The integration of algae as a power and control mechanism for robots bypasses the need for complex electronics or external chemical baths, suggesting a future of simpler, more resilient robotic designs. While current speeds are slow, the potential for long-term operation with minimal input positions these bioactuators for niche applications like automated agricultural tasks or microfluidic control systems, as well as general underwater robotics.