By Clinton Colmenares
Photography by Josh Wilson
Rodrigo Martinez-Duarte is using bacteria to create advanced materials
In his lab at Clemson University, mechanical engineer Rodrigo Martinez-Duarte and his students are coaxing bacteria into weaving materials.
“We’re trying to use bacteria as a factory” says Martinez-Duarte, an associate professor in the College of Engineering, Computing and Applied Sciences.
Not just any factory, but a tiny 3D printers of sorts, weaving cellulose fibers into engineered films with a multitude of potential uses, from sensors to battery capacitors to scaffolding for human tissue. The goal is a cleaner, more sustainable material than those currently made from petroleum, like plastic.
For a university with a rich history in textile engineering, it’s fitting that futuristic bacterial nanoweaving has its roots here. And Martinez-Duarte sees unlimited growth potential with highly customized materials.
“Once you have full control of the structure, you can start changing the physical and chemical properties of the structure itself,” he says.
Martinez-Duarte has already established a name for himself among peers by carving out a niche: he’s a mechanical engineer using electrical engineering techniques on living organisms to make advanced materials.
“He’s pushing things forward and is one of the most promising people in our field,” says Rafael Davalos, a professor of biomedical engineering and mechanics at Virginia Tech.
GO TO THE LIGHT
In his Multiscale Manufacturing Lab, students feed acetobacter bacteria a steady diet of sugar water. The bacteria “eat” the sugar water and turn it into cellulose, the same stuff found in trees and cotton. Left to its own devices, the byproduct is a mass of fibers that congeals into what’s technically known as a pellicle: a blob that looks like wet bread.
The challenge is transforming the randomly structured blob into something more useful by wrangling the cells into a more regimented formation. First, the cells have to be separated, which, at the moment, can only be done one at a time. Ultimately, Martinez-Duarte wants to move a whole army of cells, each one marching along specific lines — up, down, over, weaving in and out of each other — laying down cellulose thread as they go.
He’s making steady progress by sorting the cells with a technology called light-induced dielectrophoresis, which uses electric fields to exploit the cells’ natural inclination of attraction or repulsion to electric field gradients.
Martinez-Duarte and his team generate these electric field gradients using light patterns created with a light projector coupled to precise optics. Cells respond to such a gradient by moving either toward or away from it. In videos of their work, cells are seen separating from a cluster and following the light, like a cat chasing a laser pointer.
After showing basic movement of the acetobacter bacteria, Martinez-Duarte is now working to implement designed trajectories using fungal cells.
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