New laser direct-printing technique

 

Laser direct-writing appears to be a very interesting tool for microfabrication, with applications ranging from the well established microelectronics industry to more emerging fields like lab-on-a-chip manufacturing. The best known additive laser-direct writing technique is possibly laser-induced forward transfer (LIFT). In LIFT, laser pulses are used to transfer small amounts of liquid from a previously prepared donor thin film to a receptor substrate, placed parallel and at a short distance from the film. Thus, LIFT acts as a microprinting technique, in a very similar way to inkjet printing, but with clear advantages over it, like a potentially higher resolution or a much wider range of printable rheologies. However, the LIFT technique is not free from drawbacks, being the preparation of the donor liquid in thin film form the main obstacle for its further implementation in an industrial process.

In our research group we have developed a new laser microprinting technique [1, 2] which allows printing transparent liquids avoiding the drawbacks associated with the preparation of those liquids in thin film form. The principle of operation consists in strongly focusing an ultrashort laser pulse underneath the free surface of the liquid, which is contained in a reservoir. Subsurface absorption of the laser radiation results in the propulsion of liquid away the free surface, leading to material deposition on a substrate facing that surface (Figure 1). We have demonstrated that the technique results in the deposition of uniform circular droplets with excellent reproducibility and resolution (Figure 2), and that it is feasible for printing materials such fragile as biomolecules without harm (Figure 3).

 

 

FIGURE 1

FIGURE 2

FIGURE 3

[1] P. Serra, M. Duocastella, J.M. Fernández-Pradas, J.L. Morenza, Apparatus and method for laser direct-printing. Patent application ES-200901669 (2009)

[2] M. Duocastella, J.M. Fernández-Pradas, J.L. Morenza, D. Zafra, P. Serra, Novel laser printing technique for miniaturized biosensors preparation, Sens. Act. B: Chem., (2009) doi: 10.1016/j.snb.2009.11.055