Engineers at the University of Illinois have created a new "species" of swimming micro-organisms. They hope these could one day develop into "smart structures" that could help with delivering drugs or targeting cancer.
These wonders of modern engineering are a miniature mix of biological and engineered components. Unlike complex but morally ambiguous famous movie "cyborgs," though, these bio-bots consist of just a simple head and tail - similar to single-celled, long-tailed swimming creatures such as sperm.
The body is made from flexible polymer, while the swimming motion is actually provided by a cluster of heart cells. The heart cells have been cultured by the engineers, but within the bio-bots, these biological cells communicate with one another and arrange themselves independently.
The cells need to beat as one in the correct direction in order to make the tail move. When the cells synchronize, they send a wave down the tail that propels the bot forward.
But exactly how the cells do this is not quite understood. "It's the minimal amount of engineering - just a head and a wire," Prof. Taher Saif, of the University of Illinois, says. "Then the cells come in, interact with the structure, and make it functional."
What can swimming bio-bots do for us?
The engineers behind this project have big ideas for their little bio-bots.
"The long-term vision is simple," says Saif. "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?"
These aquatic bio-bots are the latest innovation from a wider program on "emergent behaviors in integrated cellular systems" supported by the National Science Foundation.
In 2012, the same team premiered a similar engineering project, this time involving 7-mm-tall walking bio-bots.
These bio-bots functioned in a similar way to their swimming younger siblings and were made from a combination of 3D-printed polymer and heart cells from rats.
At the time, Rashid Bashir, director of the University of Illinois' Micro and Nanotechnology Laboratory, said:
"The idea here is that you can do it by forward-engineering. We have the design rules to make these millimeter-scale shapes and different physical architectures, which hasn't been done with this level of control. What we want to do now is add more functionality to it."
In both the swimming and walking bots, this extra functionality might mean engineering bots can sense and automatically target particular chemicals. Saif's team has already begun experimenting with multiple-tailed swimming bots, which open up the potential for navigation.
The team has created an animation of how the swimming bio-bots work (below) and an actual video of one of the little guys in action.
"The most intriguing aspect of this work is that it demonstrates the capability to use computational modeling in conjunction with biological design to optimize performance, or design entirely different types of swimming bio-bots," says Roger Kamm, director of the Science and Technology Center on Emergent Behaviors in Integrated Cellular Systems.
"This opens the field up to a tremendous diversity of possibilities. Truly an exciting advance," he adds.