If you're going to deploy robots in biological settings – for example, inside the body – it makes a lot of sense to build those robots out of actual biological body parts. Muscle, for example, is a very effective, biodegradable replacement for an electric actuator that can run in a nutrient-rich fluid without the need for any other power source. Bio-robotics experts in Illinois have demonstrated a bio-bot built from 3-D printed hydrogel and spinal muscle tissue that can "walk" in response to an electrical signal. Their next step will be trying to incorporate neurons that can get the bot walking in different directions when faced with different stimuli.

Less than a centimeter in length, the "bio-bot" responds to electrical impulses that cause the muscle to contract. Previous versions, using heart muscle tissue, were also able to "walk" but were not controllable, as heart tissue contracts constantly of its own accord, where spinal muscle responds to external electrical stimuli.

Using muscle tissue to power a robot is undeniably cool – but what purpose does it serve? Well, according to study leader, Professor Rashid Bashir, biological tissue has several advantages over other robotic actuators: "[Muscle] is biodegradable, it can run in fluid with just some nutrients and hence doesn't need external batteries and power sources – and it could eventually be controlled by neurons in our future work."

These features open up a range of potential uses. Bio-robots could operate inside the body in medical applications, or be used outdoors in environmental services.

This first bio-robot is a simple design – two feet, a flexible spine and a contracting muscle – but with the technology proven, Bashir and his team are looking to start extending toward more complex machines.

Initially, they'll look at designing a more complex hydrogel backbone that gives the robot the ability to move in more than one direction. They're also looking at integrating neurons to steer the tiny bots around, either using light or chemical gradients as a trigger. This would be a key step toward being able to design bots for a specific purpose.

“The idea of doing forward engineering with these cell-based structures is very exciting,” Bashir said. “Our goal is for these devices to be used as autonomous sensors. We want it to sense a specific chemical and move towards it, then release agents to neutralize the toxin, for example. Being in control of the actuation is a big step forward toward that goal.”

The following video by Caroline Cvetkovic, Doug Litteken and Ritu Raman takes us through the bio-bot research project.

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