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LIFT hydrogel printing: A defined route for highly controlled process
decision tree, you can get a successful printing, sequential selection of easily variable parameters
changing the most accessible parameters and for a particular experiment.
analyzing the results without using additional The scheme shows an algorithm that allows for
expensive equipment such as high-speed shooting. quick configuration of the laser printing process
From a practical point of view, the most optimal to achieve the optimal regime, which forms
algorithm for producing “quality” droplets of “quality” droplets from the bioink with the given
a given size is based on the variation of easily parameters. Based on the technical specifications
changeable parameters of the laser, such as energy for the formation of 2D or 3D structures,
per pulse (E) and spot size (SS), as well as at the the optimal diameter of hydrogel droplets is
distance between the donor and acceptor (D). In determined. Subsequently, the parameters of
some cases (for example, if very large or very the experiment, namely, Energy (E), Distance
small droplets are needed), the thickness of the (D), Thickness (T), and Spot size (SS) are set
hydrogel layer (T) on the donor ribbon can also and a trial transfer is performed. Based on the
be varied. results of our works [13,32,44,63,64] and the results
Figure 8 shows a decision tree, which allows of other authors [14,15,54] , for a wide variety of
for achieving an optimal printing regime by hydrogels [24,65,66] , the threshold fluence is 2 – 3 J/

Figure 8. Decision tree for achieving a success story with laser-induced forward transfer. The symbol “↓”
represents a decrease, “↑” an increase, and “↓ ↑” a variation.

88 International Journal of Bioprinting (2020)–Volume 6, Issue 3