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New Nanofiber Fabrication Device Offers Accurate Point-And-Shoot Capability

Scanning electron microscopy image of nanofibers woven into threads (Christophe Chantre/Harvard University)

A portable, lightweight nanofiber fabrication device that could at some point in time be used to dress shoppers in customizable fabrics or dress wounds on a battlefield has been developed by Harvard researchers.

The research was recently featured in Macromolecular Materials and Engineering.

Nanofibers can be produced in a number of ways. The key applications of these versatile materials include almost everything starting from bullet proof vests to engineering. Nanofibers were developed using capillary force, centrifugal force, blowing, evaporation, stretching, electric field, and melting.

All these fabrication methods have their own advantages and disadvantages. For instance, Immersion Rotary Jet-Spinning (iRJS) and Rotary Jet-Spinning (RJS) are novel manufacturing methods developed in the Disease Biophysics Group at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering.

Both iRJS and RJS dissolve proteins and polymers in a liquid solution and employ precipitation or centrifugal force to elongate and solidify polymer jets into nanoscale fibers. These methods are considered to be great for developing increased amounts of a wide range of materials, including nylon, DNA, and even Kevlar, but until now they have not been specifically portable.

Recently, the Disease Biophysics Group announced the development of a hand-held device capable of developing nanofibers with accurate control over fiber orientation. It is essential to regulate fiber alignment and deposition when constructing nanofiber scaffolds that imitate highly aligned tissue in the body or designing point-of-use garments that fit a particular shape.

Our main goal for this research was to make a portable machine that you could use to achieve controllable deposition of nanofibers. 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.

Nina Sinatra, Graduate Student, Disease Biophysics Group, SEAS

The newly developed fabrication method, called pull spinning, employs a high-speed rotating bristle that dips into a protein reservoir or polymer. This is then followed by pulling a droplet from a solution into a jet. The fiber passes through a spiral trajectory and then solidifies prior to separating from the bristle and moving in the direction of a collector.

One processing parameter, called solution viscosity, is required by pull spinning in order to regulate nanofiber diameter, unlike other processes, which require multiple manufacturing variables. Minimal process parameters translate to effortless usage and flexibility at the bench and, some day, even in the field.

Pull spinning operates with a wide range of proteins and polymers. Proof-of-concept applications were demonstrated by the researchers through the use of the polycaprolactone and gelatin fibers in order to direct muscle tissue growth and function on bioscaffolds, and polyurethane and nylon fibers for point-of-wear apparel.

This simple, proof-of-concept study demonstrates the utility of this system for point-of-use manufacturing. 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.

Kit Parker, Tarr Family Professor of Bioengineering and Applied Physics and director of the Disease Biophysics Group

Coauthors of the research include Leila F. Deravi, Christophe O. Chantre, Alexander P. Nesmith, Hongyan Yuan, Sahm K. Deravi, Josue A. Goss, Luke A. MacQueen, Mohammad R. Badrossamy, Grant M. Gonzalez and Michael D. Phillips.

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