Scientists make nanofibers using fridge magnet and ferrofluid

Researches from the University of Georgia, Princeton University and Oxford University report a new method for nanofiber production using a permanent magnet and ferrofluid – magnetospinning. Results of this research are published in Advanced Materials journal - http://onlinelibrary.wiley.com/doi/10.1002/adma.201500374/abstract

A ferrofluid is a colloidal dispersion of stabilized magnetic nanoparticles that responds to an external magnetic field: above a critical value for a uniform field the surface of the ferrofluid deforms and a liquid spike is formed on the surface. In addition, as a magnet approaches an interface, the field is nonuniform, the interface always deforms, so the spike moves towards the magnet and forms a liquid bridge. This instability was explored in this work in a new method for drawing polymeric nano and microfibers in which the magnetic force generated by a permanent magnet is used to draw fibers with controlled diameters in the 0.05–5 µm range. As the magnet approaches the ferrofluid the magnetic force attracts the droplet towards the magnet and a liquid bridge between the magnet and the needle is formed. The magnet moves away and draws the polymer fiber while the solvent evaporates. The resulting nanofibers are spooled on a reel that is attached to the opposite side of the stage.

The new method provides excellent control over the fiber diameter and is compatible with a range of polymeric materials and polymer composite materials including biopolymers. This research showcases new technique and demonstrates its advantages to the scientific community. For example, polymers with low dielectric constant cannot be electrospun without adding high dielectric constant ingredients but can be easily magnetospun, for example Teflon© fluoropolymer fibers that are ideal for the design of superhydrophobic materials. Owing to its simplicity and low costs, magnetospinning set-up could be installed in any non-specialized labs for broader uses of magnetospun nanofibers in different methods and technologies. Electrospinning is the most popular method to produce nanofibers in labs now. The total cost of a laboratory electrospinning system is above ~$10K. In contrast, it is possible to build a magnetospinning set-up, such as we utilize, by just using a $30 rotating motor and a $5 permanent magnet. No special equipment is needed for magnetospinning.
Researches showed that the productivity and scalability in magnetospinning is comparable with electrospinning methods and demonstrated universality of the new method by fabricating several examples of different polymeric fibers, including Teflon© fibers, fibers with aligned carbon nanotubes, silver nanowires, and porous fibers – all obtained with the same experimental set-up.