Easy Printing of High Viscous Microdots by Spontaneous Breakup of Thin Fibres

Electro-hydrodynamic jetting is emerging as a successful technique for printing inks with resolutions well beyond those offered by conventional inkjet printers. However, the variety of printable inks is still limited to those with relatively low viscosities (typically < 20 mPa s) due to nozzle clogging problems. Here we show the possibility of printing ordered microdots of high viscous inks such as the poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fibre generated through nozzle-free pyro-electrospinning (PES). The PLGA fibre is deposited onto a partially wetting surface and the breakup is achieved simply by applying an appropriate thermal stimulation, able to induce polymer melting and hence a mechanism of surface area minimization due to the Plateau-Rayleigh instability. The results show that the technique is a good candidate for extending the printability at microscale to high viscous inks, thus extending their applicability to additional applications, such as cell behaviour under controlled morphological constraints.