Tunable bead-on-string microstructures fabricated by mechano-electrospinning

Abstract

In this paper, bead-on-string microstructures are fabricated by the mechano-electrospinning (MES) process in a continuously tunable manner. The thin jet is pulled onto the substrate by the stable electric field force and tunable mechanical drawing force, and then the bead-on-string structures are generated by means of the force exerted on the jet, which changes from capillary force and resisting viscosity force to friction force at the contact point in the horizontal direction. In a stable bead-on-string formation process, one cycle can be divided into three stages from the point of view of the jet behaviour: being anchored, being stretched, and skipping. The bead size and the bead gap are continuously tunable through the MES process. The fabrication mechanisms of the bead-on-string microstructure are uncovered through theoretical analysis and experimental characterization. When a critical velocity is achieved, the jet directly falls on the substrate without accumulation since the mechanical drawing force in the horizontal direction overtakes the capillary force, which leads the bead-on-string microstructures to a continuous fibre line. It is a flexible and highly controllable method to fabricate bead-on-string microstructures.

Sustained Release of Protein Particle Encapsulated in Bead-on-String Electrospun Nanofibers

“…In electrospinning it is known that a phenomenon of so-called bead-on-string [21,22] can be observed with appropriate spinning parameters. There are various shapes and surface morphologies of beaded nanofibers [22][23][24][25] .…”

Pattern stretchable micro-nano thin film via Electrohydrodynamic Direct-Writing

“…DC high voltage source supplied an electrostatic field between the spinneret and the collector, which drew the polymer solution into Taylor cone and formed charged jet. Applied voltage and solution concentration were the important roles that define the morphology and line width of EDW micro/nano thin film [17,20]. Charged jet would be elongated and thinned by the electrostatical field force during the falling process.…”

“…PEO could be dissolved in various kinds of solvents, such as water, alcohol, etc. [24], and had been widely used to carry out many kinds of experiment in the field of electrospinning [17][18][19][23][24]. The PEO solution properties could be adjusted easily by changing the solution concentration, which contributed significantly to the controlling technology research of mechanical and electrical spinning process.…”

“…When the collector motion speed is larger than the deposition speed, the drag force from the collector would decrease the diameter of charged jet. N. B. Bu et al [17] build up a novel method called mechano-electrospinning, in which the drag force stemmed from the moving collector is utilized to stretch the charged jet and decrease the diameter of electrospinning nanofiber. Due to the short distance between spinneret and collector, solvent in charged jet wasn't evaporated absolutely.…”

Non-contact printing of high aspect ratio Ag electrodes for polycrystalline silicone solar cell with electrohydrodynamic jet printing

“…The surface flow of the printed ink would produce the bulging, which might be also observed in the nanofiber electrospinning. 12 To avoid the bulging happened at low speed, we could optimize the printing speed. We could pattern the fine electrode when the substrate had higher contact angles (lower surface energy).…”