Film-free laser forward printing of transparent and weakly absorbing liquids

Abstract

A laser-based technique for printing transparent and weakly absorbing liquids is developed. Its principle of operation relies in the tight focusing of short laser pulses inside the liquid and close to its free surface, in such a way that the laser radiation is absorbed in a tiny volume around the beam waist, with practically no absorption in any other location along the beam path. If the absorbed energy overcomes the optical breakdown threshold, a cavitation bubble is generated, and its expansion results in the propulsion of a small fraction of liquid which can be collected on a substrate, leading to the printing of a microdroplet for each laser pulse. The technique does not require the preparation of the liquid in thin film form, and its forward mode of operation imposes no restriction concerning the optical properties of the substrate. These characteristics make it well suited for printing a wide variety of materials of interest in diverse applications. We demonstrate that the film-free laser forward printing technique is capable of printing microdroplets with good resolution, reproducibility and control, and analyze the influence of the main process parameter, laser pulse energy. The mechanisms of liquid printing are also investigated: timeresolved imaging provides a clear picture of the dynamics of liquid transfer which allows understanding the main features observed in the printed droplets.

Exploration of water jet generated by Q-switched laser induced water breakdown with different depths beneath a flat free surface

“…The oscillation times of a cavitation bubble near a rigid wall and free surface were investigated and compared with modified Rayleigh's model [12]. Very recently, a liquid jet on a flat free surface induced by a femtosecond pulsed laser was implemented in a new laser printing technique named film-free laser induced forward transfer (LIFT) to overcome the constraint of solid or liquid film preparation [17]. However, a liquid jet on a flat free surface by using a nanosecond pulsed laser with milli-joule energy has not yet been observed.…”

[INVITED] Laser-induced forward transfer: A high resolution additive manufacturing technology

“…The main difference with previous experiments is that the DRL does not break during the process and then there is no generation of debris from the DRL ablation that could pollute the printed droplets. One can also mentioned a film-free approach that allows printing transparent liquids [65]. The liquid is contained in a reservoir and the receiver is located close to the free surface.…”

Laser-assisted bioprinting at different wavelengths and pulse durations with a metal dynamic release layer: A parametric study

“…Duocastella et al [11] printed a glycerol-water blend using laser with 1027-nm wavelength and 450-fs pulse duration. Desrus et al [12] printed cell medium and a glycerol-water blend, as well as keratinocytes with cell medium using 1030-nm laser wavelength, and 350-fs and 800-fs pulse durations.…”