Biomimetics—the use of designs and systems found in nature to inspire engineering solutions—has been a fertile field of innovation. A recent example comes from the University of Illinois at Urbana-Champaign, where researchers are developing so-called bio-bots.
Less than 1 cm in size, the bio-bots are constructed from flexible 3D-printed hydrogels and living cells. The muscle cells are jolted with electrical pulses to create contractions, and, thus, movement. It’s one small step toward biological machines that can be stimulated, trained, or programmed to do work, say researchers. Possible applications include drug-delivery systems, surgical robotics, smart implants, and mobile environmental analyzers, but the possibilities are, in fact, endless. The research group led by Rashid Bashir, Abel Bliss Professor and head of bioengineering at the U. of I, published its work in the online early edition of Proceedings of the National Academy of Science
“Skeletal muscles cells are very attractive because you can pace them using external signals,” says Bashir. “For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it’s part of a design toolbox. We want to have different options that could be used by engineers to design these things.”
The design is inspired by the muscle-tendon-bone complex found in nature. A backbone of 3D-printed hydrogel is strong enough to give the bio-bot structure but flexible enough to bend like a joint. Two posts serve to anchor a strip of muscle to the backbone, in the way that tendons attach muscle to bone, but the posts also act as feet for the bio-bot. The frequency of electric pulses control the bot’s speed. A higher frequency causes the muscle to contract faster, thus speeding up the bio-bot’s progress as seen in the video below.
Moving forward, the researchers want to achieve greater control over the bio-bots’ motion. By integrating neurons, for example, they can be steered in different directions using light or chemical gradients. They also hope to engineer a hydrogel backbone that allows the bio-bot to move in different directions based on different signals. Thanks to 3-D printing, engineers can explore different shapes and designs quickly.
“The idea of doing forward engineering with these cell-based structures is very exciting,” says Bashir. “Our goal is for these devices to be used as autonomous sensors. We want it to sense a specific chemical and move toward it, then release agents to neutralize the toxin, for example. Being in control of the actuation is a big step forward toward that goal.”
Graphic courtesy Janet Sinn-Hanlon, Design Group@VetMed.
