These are scanning electron microscopy images of various scaffold structures and fiber alignments. Images: Christophe Chantre/Harvard University.Researchers at Harvard University have developed a lightweight, portable nanofiber fabrication device that could one day be used to dress wounds on a battlefield or dress shoppers in customizable fabrics. The device is described in a paper in Macromolecular Materials and Engineering.
There are many ways to make nanofibers. These versatile materials – with potential applications that stretch from tissue engineering to bullet proof vests – have been made using centrifugal force, capillary force and electric fields, as well as stretching, blowing, melting and evaporation.
Each of these fabrication methods has pros and cons. For example, rotary jet-spinning (RJS) and immersion rotary jet-spinning (iRJS) are novel manufacturing techniques 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 RJS and iRJS work by dissolving polymers and proteins in a liquid solution, and then using centrifugal force or precipitation to elongate and solidify polymer jets into nanoscale fibers. These methods are great for producing large amounts of a range of different materials – including DNA, nylon and even Kevlar – but they aren’t particularly portable.
The Disease Biophysics Group has now developed a hand-held device that can quickly produce nanofibers with precise control over fiber orientation. Regulating fiber alignment and deposition is crucial when building nanofiber scaffolds that mimic highly-aligned tissue in the body or designing 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," said Nina Sinatra, a graduate student in the Disease Biophysics Group and co-first author of the paper. "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 technique they came up with is called pull spinning, which involves dipping a high-speed rotating bristle into a polymer or protein reservoir and pulling a droplet from the solution into a jet. The fiber travels in a spiral trajectory and solidifies before detaching from the bristle and moving toward a collector. Unlike other processes, which involve multiple manufacturing variables, pull spinning requires only one processing parameter – solution viscosity – to regulate nanofiber diameter. A low number of process parameters translates into ease of use and flexibility at the bench and, one day, in the field.
Pull spinning works with a range of different polymers and proteins. The researchers demonstrated proof-of-concept applications by using it to produce polycaprolactone and gelatin fibers for directing 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," said Kit Parker, a professor of bioengineering and applied physics and director of the Disease Biophysics Group. "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."
This story is adapted from material from the Harvard John A. Paulson School of Engineering and Applied Sciences, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.