Reduction of Transfer Threshold Energy for Laser-Induced Jetting of Liquids using Faraday Waves

Flow-focusing is used in microfluidics to generate droplets that are smaller than the characteristic length scale of the flow geometry. Conventionally, flow-focusing takes place inside micrometer-sized channels due to capillary effects. In this study, we demonstrate that the transient meniscus profile created with Faraday waves on liquid films can enable flow-focusing. Using a magnetic shaker, we generate Faraday waves on a liquid film leading to flow-focusing that increases the resolution of a nozzleless, jet-based printing technique called blister-actuated laser-induced forward transfer (BALIFT). We perform experiments to demonstrate how transient meniscus formation enables jetting at lower laser-pulse energies than the threshold, and use numerical modeling to examine this process at smaller length scales relevant to printing applications.