Tiny Swimming Bio-Bots Boldly Go Where No Bot Has Swum Before

The alien world of aquatic micro-organisms just got new residents: synthetic self-propelled swimming bio-bots.

A team of engineers has developed a class of tiny bio-hybrid machines that swim like sperm, the first synthetic structures that can traverse the viscous fluids of biological environments on their own. Led by Taher Saif, the University of Illinois Gutgsell Professor of mechanical science and engineering, the team published its work in the journal Nature Communications.

"Micro-organisms have a whole world that we only glimpse through the microscope," Saif said. "This is the first time that an engineered system has reached this underworld."

The bio-bots are modeled after single-celled creatures with long tails called flagella - for example, sperm. The researchers begin by creating the body of the bio-bot from a flexible polymer. Then they culture heart cells near the junction of the head and the tail. The cells self-align and synchronize to beat together, sending a wave down the tail that propels the bio-bot forward.

This self-organization is a remarkable emergent phenomenon, Saif said, and how the cells communicate with each other on the flexible polymer tail is yet to be fully understood. But the cells must beat together, in the right direction, for the tail to move.

"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."