Pull Spinning is a novel nanofiber manufacturing process developed in the Disease Biophysics Group at Harvard SEAS. The original inspiration for the method was the motion of a cat's tongue as it draws milk from a saucer, and the technique has evolved to a portable, point-of-use fiber fabrication system that supports a wide range of polymer and protein materials.

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Unlike many other nanofiber fabrication systems, pull spinning does not rely on a high electric field to extrude nanofibers. Instead, a combination of viscous and centrifugal forces contribute to nanofiber formation:

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• First, a polymer, protein, or biohybrid solution is infused through a needle reservoir.

• Then, a rotating bristle attached to a high-speed motor strikes the droplet that forms at the top of the needle. The bristle pulls and elongates the droplet into a polymer jet within 35 milliseconds.

• As the bristle pulls the jet through one revolution, the solvent evaporates from the polymer solution, forming a single nanofiber.

• As the bristle subsequently contacts the polymer reservoir, the nanofiber is projected linearly toward a collector. This process continues until a network of nanofibers have formed.

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Pull spun nanofabrics can be used for a variety of applications, including muscle tissue engineering and point-of-wear apparel. The combination of minimal processing parameters, portability, high control of fiber deposition, flexible substrate materials distinguish pull spinning as a robust and easy- to-use platform for nanofiber manufacturing. 

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This project was published on the cover of Macromolecular Materials and Engineering.