Bio-bots combine cultured cells with polymer structure

Engineers have developed a class of bio-hybrid machines that swim like flagella, 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 Nature Communications.

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

The bio-bots are modelled after flagella, which are single-celled creatures with long tails such as 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-organisation 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.’

The team also built two-tailed bots, which they found can swim even faster. Multiple tails also opens up the possibility of navigation with the researchers envisioning future bots that could sense chemicals or light and navigate toward a target for medical or environmental applications.

‘The long-term vision is simple,’ said 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?’

The swimming bio-bot project is part of a larger US National Science Foundation-supported Science and Technology Center on Emergent Behaviors in Integrated Cellular Systems.

A video of a free-swimming bot can be found here.