These tiny self-propelled bio-bots swim like sperm.

A team of engineers at the University of Illinois at Urbana-Champaign has built the first synthetic structures that can move through the viscous fluids of biological environments unaided.

“Micro-organisms have a whole world that we only glimpse through the microscope,” explained Taher Saif, the University of Illinois Gutgsell Professor of mechanical science and engineering. “This is the first time that an engineered system has reached this underworld.”

According to the team of engineers, the bio-bots are modeled after single-celled structures with long tails called flagella — for instance, sperm. Engineers begin by constructing the body of the bio-bot from a bendable polymer. Then they culture heart cells near the confluence of the head and the tails. Amazingly, the cells self-align and synchronize to beat together, sending a wave down the tail that propels the sperm-like bio-bot forward. The cells must beat as one, in the correct direction, for the tail to work properly.

“It’s the minimal amount of engineering – just a head and a wire,” Saif said. “Then the cells come in, interact with the structure, and make it functional.”

The engineers also built two-tailed bots, which they found can swim even faster than the one-tailed bots. What does the future hold for these self-propelled bio-bots? Saif and his team envision future bots that could sense chemicals or light and travel toward a target to deliver drugs.

“The long-term vision is simple,” Saif posited. “Could we make elementary structures and seed them with stem cells that would differentiate into smart structures to deliver drugs, perform minimally invasive surgery or target cancer?”

Read more about the achievement in the journal Nature Communications.