Famed sci-fi author Arthur C. Clarke called them biots—biological robots that use real muscle tissue to walk or crawl. While they’ve been created in the lab, today’s biobots are currently little more than strips of muscle that inch across surfaces like caterpillars. But researchers predict machines guided by primitive artificial brains of their own, machines that could one day travel inside the body to conduct minimally invasive surgery or even venture out into the world to clean up pollution.
Biorobotics is a term that loosely covers the fields of cybernetics, bionics and even genetic engineering as a collective study.
Biorobotics is often used to refer to a real subfield of robotics: studying how to make robots that emulate or simulate living biological organisms mechanically or even chemically. The term is also used in a reverse definition: making biological organisms as manipulatable and functional as robots, or making biological organisms as components of robots.
Bioengineer Rashid Bashir at the University of Illinois, Urbana-Champaign, and his colleaguescreated their first bio-bots in 2012. The team used heart muscle cells, which contract spontaneously, potentially making them difficult to control for use in future applications. This week, though, the researchers debuted a biobot made with skeletal muscle, the same kind found in limbs, which suggests biobots could be controlled precisely for complex activities.
“Our goal is to harness the power of mammalian cells, which have evolved over billions of years to do what they do,” Bashir says.
The researchers created their new 6-mm-long biobots using 3D printers. First they printed scaffolds made of a hydrogel similar to the polymer material making up soft contact lenses, creating a bench-like structure consisting of stiff pillars connected by a flexible plank. Next they deposited living rat skeletal muscle cells, which formed a strip of muscle connecting both feet of the scaffold’s pillars.
In experiments, the scientists placed their biobots in lab dishes filled with a warm, electrically conductive fluid. When the dishes were zapped with a series of electrical pulses, the biobots moved by inching across the dishes at rates of a little more than one-third of an inch per minute. The researchers detailed their findings in the journal Proceedings of the National Academy of Sciences.
The biobots created so far are relatively simple. “We now have a toolbox of cells and polymer materials that can be used by engineers to design new biological machines,” Bashir says.
Currently biobots need to be surrounded by warm fluids to survive. Still, this means they could find applications in the body, either crawling around or even swimming.
“You can imagine biobots reaching someplace inside the body to remove a small bit of tissue for minimally invasive surgery,” says study coauthor Taher Saif, a mechanical engineer at the University of Illinois at Urbana-Champaign. Also, “instead of having drugs going all over the body, maybe designed to specifically go after some chemical targets, you can have a biobot with neurons and sensors to more intelligently go after specific targets.”
To work outside the body, biobots will likely need some kind of shell, perhaps one made of polymer. If it worked, “you can imagine them removing a toxin from the environment, many groups of them acting like scavengers to sense and consume things that need to be removed or made less toxic,” Saif says.
“In the long term, essentially anything that a current robot does could be envisioned as being done by a biological robot. In particular, tasks that require fine motor control might be best suited to a biobot hand or arm,” Kamm says. “Some of the advantages in using biological systems is that they could adapt to changing demands and self-repair.”