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Figure 6. The dependence of the bubble and jet volume on the laser energy for three viscosities
(2.8 cP – left; 75 cP – middle; 165 cP – right).

4. Discussion

This study aimed to develop and validate a mobile LIST printing platform, with a focus on

investigating critical parameters that influence print quality, including head-to-substrate distance,
ink viscosity, and motion compensation. Below, we discuss the key findings in relation to current

limitations and future directions in laser-based DoD printing.

Shape fidelity is crucial in bioprinting because it determines how closely a printed structure

matches its intended design. In drop-DoD printing, maintaining high fidelity in printed structures

requires precise placement of each droplet on the substrate with minimal deviation or splashing.
In this work a printing head-to-target distance of 3 mm was the upper limit for ensuring splatter-

free printing. Distances greater than 3 mm resulted in a significant increase in splatter coverage,
which reached 37.36 ±13.01% at 24 mm. This increase can be attributed to the longer flight

distance of the droplet, which increases its exposure to aerodynamic forces, causing potential
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disruptions in its shape or trajectory . These disturbances may lead to droplet breakup into smaller
droplets or scattering upon impact. To mitigate this, increasing the droplet ejection speed can

reduce flight time and make the process less sensitive to variations in printing head-to-substrate
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distance, thereby improving positional accuracy . However, caution is needed when increasing
jet speed to avoid splashing upon substrate impact or unintended jet penetration, particularly if the

target is soft.

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