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Abstract

We present a mobile drop-on-demand (DoD) printing system based on laser-induced side transfer

(LIST). By replacing the bulky free-space optics used in previous LIST configurations with a fiber-
based laser delivery system, we developed a compact printing head and integrated it as an end-

effector onto a robotic arm. Using model inks with viscosities up to 165 cP and time-resolved

imaging, we investigated printability, printing dynamics, and the effect of printing head-to-
substrate distance on key printing quality metrics. We found that printing quality deteriorates

significantly beyond a 3 mm standoff distance. To address motion-induced printing quality loss on
dynamic substrates, we integrated a custom-built fiber-optic distance sensor that actively maintains

a constant standoff distance in real time. This enabled high-quality printing on moving targets

simulating physiological motion. Additionally, we characterized the influence of ink viscosity and
laser energy on droplet formation dynamics and ejected volume. Our results demonstrate the

feasibility of motion-compensated, laser-assisted DoD printing in dynamic environments, with
potential applications in intraoperative tissue engineering.

Keywords: Laser-induced side transfer (LIST); Drop-on-demand; Distance sensor; Motion

compensation; In situ bioprinting; Robotic

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