Simulation of cavitation effects in blister-assisted laser-induced forward transfer of fluids

In Blister-Actuated Laser-Induced Forward Transfer (BA-LIFT), a laser pulse generates a blister in an intermediate polyimide layer to push away the fluid. In this work, a Phase Field model has been proposed to study the transference mechanisms. Simulations and experimental shadowgraphy images for BA-LIFT of water-glycerol mixtures have been compared. The transference mechanism in BA-LIFT is ideally only mechanical and does not explain some secondary effects in the jet expansion that have already been described in other LIFT techniques and associated with the cavitation of a thermally generated vapor bubble.The numerical model can reproduce the expansion of the main jet. The addition of a second push at 9 μs delay allows reproducing the secondary effects. Four possible causes of the second push have been studied: absorption of the laser pulse in the fluid, thermal conduction through the polyimide layer, a mechanical rebound of the elastically deformed blister, or pressure fall due to fluid velocity. After the analysis, the first three explanations have been rejected, and a hypothesis is proposed: the velocity field generated by the blister produces a cavitation bubble in the interface between the polyimide layer and the fluid, whose effects would be the same than the cavitation of the vapor bubble in other LIFT techniques.