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Scanning electron microscopy image of nanofibers woven into threads. Credit: Christophe Chantre/Harvard University

A new lightweight, portable nanofiber fabrication device may revolutionize several different fields.

The material—developed by Harvard University researchers— could be used for everything from dressing wounds on a battlefield or creating engineered tissue to improving bullet proof vests or creating fashion-forward customizable fabrics.

The Disease Biophysics Group at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) recently announced the development of a hand-held device that can quickly produce nanofibers with precise control over fiber orientation.

By regulating fiber alignment and deposition, scientists can build nanofiber scaffolds that mimic highly aligned tissue in the body or design point-of-use garments that fit a specific shape.

“Our main goal for this research was to make a portable machine that you could use to achieve controllable deposition of nanofibers,” Nina Sinatra, a graduate student in the Disease Biophysics Group and co-first author of the paper, said in a statement. “In order to develop this kind of point-and-shoot device, we needed a technique that could produce highly aligned fibers with a reasonably high throughput.”

The nanofibers have been made using centrifugal force, capillary force, electric field, stretching, blowing, melting and evaporation.

Rotary Jet-Spinning (RJS) and Immersion Rotary Jet-Spinning (iRJS) both dissolve polymers and proteins in a liquid solution and use centrifugal force or precipitation to elongate and solidify polymer jets into nanoscale fibers, making these methods ideal for producing large amounts of materials including DNA, nylon and even Kevlar.

However, before the Harvard experiment they have not been particularly portable.

The new fabrication method—called pull spinning—uses a high-speed rotating bristle that dips into a polymer or protein reservoir and pulls a droplet from solution into a jet. The fiber then travels in a spiral trajectory and solidifies before detaching from the bristle and moves toward a collector.

This is different from other processes that involve multiple manufacturing variables, while pull spinning requires only one processing parameter—solution viscosity—to regulate nanofiber diameter.

Minimal process parameters translate to ease use and flexibility at the bench— and one day in the field.

Pull spinning works with a range of different polymers and proteins and the researchers were able to demonstrate proof-of-concept applications using polycaprolactone and gelatin fibers to direct muscle tissue growth and function on bioscaffolds and nylon and polyurethane fibers for point-of-wear apparel.

“This simple, proof-of-concept study demonstrates the utility of this system for point-of-use manufacturing,” Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics and director of the Disease Biophysics Group, said in a statement. “Future applications for directed production of customizable nanotextiles could extend to spray-on sportswear that gradually heats or cools an athlete's body, sterile bandages deposited directly onto a wound, and fabrics with locally varying mechanical properties.”

The study was published in Macromolecular Materials and Engineering.

     

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