Micro helical polymeric structures produced by variable voltage direct electrospinning

Abstract

Direct near field electrospinning is used to produce very long helical polystyrene microfibers in water. The pitch length of helices can be controlled by changing the applied voltage, allowing to produce both micro springs and microchannels. Using a novel high frequency variable voltage electrospinning method we found the helix formation speed and compared the experimental buckling frequency to theoretical expressions for viscous and elastic buckling. Finally we showed that the new method can be used to produce new periodic micro and nano structures.

Design of a novel co‐electrospinning system with flat spinneret for producing helical nanofibers

“…Kessick and Tepper obtained helical fibers from a combination of one conducting polymer, poly (aniline sulfonic acid) (PASA), and one nonconducting polymer, poly(ethylene oxide) (PEO), by conventional electrospinning. Some other researchers also used conventional electrospinning of single polymer solution or binary polymer blend solution to obtain helices. Using co‐electrospinning technique, the researchers fabricated helical nanofibers from different polymers components.…”

Dynamic regimes of electrified liquid filaments

“…For instance, a variety of functional nanomaterials, such as metal nanowires, graphene nanosheets, carbon nanotubes, and protein nanofibrils, are incorporated into liquid precursors for printing ( 9 – 11 ). Electrically assisted printing techniques have enormous potential to achieve ultrafast and high-resolution printing with enhanced ordering of functional nanoobjects, where the liquid inks often form jets during printing ( 5 , 10 , 12 – 22 ). To engineer the printed structures at different length scales, understanding the dynamic behaviors of a liquid ink filament under an electrical field is crucial.…”

“…For electrified jets that connect the nozzle and substrate at small separation distances, such as on a printing platform, new dynamic behaviors of viscous liquid filaments occur. For example, recent studies show that a viscous filament can be triggered to coil steadily by applied electric stresses ( 18 , 20 , 26 , 35 – 38 ). However, to the best of our knowledge, the electrically induced coiling and electrospinning have not been observed in a single system for at least two reasons.…”

Rapid mixing of viscous liquids by electrical coiling

“…The control of coiling is crucial for manipulating viscous liquids in printing and dispensing applications 11 12 13 14 . For example, the well-defined attributes of coiling can be utilized to print tunable helical structures 15 16 17 18 19 20 21 22 23 . Moreover, the coiling can be used to dispense precursor liquids to form spring-like antenna for micro-electronics 11 13 , pre-mixed epoxy resins to bond electronic components onto integrated electric circuit 14 , and precursor solutions of hydrogel to fabricate scaffolds and arrays 12 .…”

“…For instance, for a jet with a viscosity of 10 3 centistoke, a dispensing height of around 140 millimeter is needed for steady coiling 3 . Thus, coiling-based printing becomes impractical for many applications where the dispensing height must be limited to the micro-meter range 15 16 17 18 19 20 21 22 23 24 25 .…”