MIT inventors of tiny artificial muscles that beat the wings of robotic insects have now added electroluminescent particles that allow them to emit colored light in flight, similar to fireflies.
The artificial muscles, called actuators, are made by alternating ultra-thin layers of elastomer and carbon nanotube electrode material and then rolling the stack of layers into a smooth cylinder. When a voltage is applied, the electrodes squeeze the elastomer and the mechanical tension flaps the wing.
To make them glow, electrical and computer engineering professor Kevin Chen and his team embedded zinc sulfate particles into the elastomer and used a very thin layer of nanotubes to avoid blocking the light. Because the particles only light up in the presence of a strong, high-frequency electric field, they use a high voltage to create that field in the actuator and then drive the robot at a high frequency. It ends up just 2.5% heavier and flight performance is not compromised.
This capability could allow robots to communicate with each other and brings micro-scale robots closer to flying on their own outside of the lab. These lightweight devices can’t carry sensors, so researchers have to track them using infrared cameras that don’t work well outdoors. Now scientists have shown they can track these robots using emitted light and three smartphone cameras.
The team is working to incorporate control signals so the robots can turn lights on and off during flight to communicate. On a search and rescue mission, for example, they could call for help.
Larger robots can use tools like Bluetooth or wireless to communicate, “but for a small robot with limited power, we’re forced to think of new modes of communication,” Chen says. “This is an important step in flying these robots in outdoor environments where we don’t have a fine-tuned, state-of-the-art motion tracking system.”