Highly Aligned Electrospun Fibers and Mats
materials and coatings
Highly Aligned Electrospun Fibers and Mats (LAR-TOPS-2)
Incorporation of an auxiliary electrode for controlled micro- or nano-fiber placement, orientation, and porosity in electrospun mats
Overview
NASA's Langley Research Center has created a modified electrospinning apparatus for spinning highly aligned polymer fibers. Fiber placement, orientation, and porosity are difficult to control using conventional electrospinning apparatus. Conventional electrospinning creates randomly
oriented fibers that are well suited to nonwoven mats, but not to other applications. Now, NASA Langley has developed the capability to control the alignment and porosity of fibers for mats, which will broaden the range of engineering applications of electrospun materials to include new tissue
engineering scaffolds, membrane filters, textiles, and embedded sensors and actuators. The new apparatus provides a simple and inexpensive means of producing fibers and mats of controlled fiber diameter, porosity, and thickness.
The Technology
Electrospinning offers a versatile way to produce one-dimensional micro- or nanometer mats; however, electrospun fibers are typically collected in a random orientation, which limits their applications. NASA has developed a new apparatus that uses an auxiliary counter electrode to align fibers for control of the fiber distribution during the spinning process. The electrostatic force imposed by the auxiliary electrode creates a converged electric field, which affords control over the distribution of the fibers on the rotating collector surface.
The process begins when a pump slowly expels polymer solution through the tip of
the spinneret at a set flow rate as a positive charge is applied. The auxiliary electrode,
which is negatively charged, is positioned opposite the charged spinneret. The disparity
in charges creates an electric field that effectively controls the behavior of the polymer
jet as it is expelled from the spinneret; it ultimately controls the distribution of the
fibers and mats formed from the polymer solution as it lands on the rotating collection
mandrel. A broad range of fiber diameters can be manufactured by modifying various
parameters of the process and/or polymer solution. Performance data has confirmed
the substantial role that the electric field plays in the significant improvement in fiber
alignment and control relative to using the rotating collector alone.
Prototypes have been produced, and the repeatability of the process has been
confirmed. A patent application has been filed.
Benefits
- Consistency and control of: --Fiber distribution --Porosity --Fiber alignment
- Versatility: adaptable to micro and nano fiber sizes
- Repeatable results: amenable to mass production
- Capable of manufacturing single fibers
- Compatible with most polymer solution systems
- Inexpensive processing method
Applications
- Biomedical - tissue engineering scaffolds for cell formation; drug delivery; wound dressing; membranes
- Military - smart textiles and embedded sensors/actuators
- Filter applications - industrial, environmental, automotive
- Instrumentation - sensors for spectroscopy
- Chemical and biological sensors
- Fuel cells and solar cells