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RESEARCH ARTICLE

Laser-assisted bioprinting at different wavelengths

and pulse durations with a metal dynamic release

layer: A parametric study

1*
1
2
1,3
Lothar Koch , Ole Brandt , Andrea Deiwick and Boris Chichkov
1 Laser Zentrum Hannover e.V., Nanotechnology Department, Hollerithallee 8, 30419 Hannover, Germany
2 DeutschesElektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany
3 Leibniz Universität Hannover, Institut für Quantenoptik, Welfengarten 1, 30167 Hannover, Germany

Abstract: For more than a decade, living cells and biomaterials (typically hydrogels) are printed via laser-assisted bio-
printing. Often, a thin metal layer is applied as laser-absorbing material called dynamic release layer (DRL). This layer
is vaporized by focused laser pulses generating vapor pressure that propels forward a coated biomaterial. Different la-
sers with laser wavelengths from 193 to 1064 nanometer have been used. As a metal DRL gold, silver, or titanium lay-
ers have been used. The applied laser pulse durations were usually in the nanosecond range from 1 to 30 ns. In addition,
some studies with femtosecond lasers have been published. However, there are no studies on the effect of all these la-
sers parameters on bioprinting with a metal DRL, and on comparing different wavelengths and pulse durations – except
one study comparing 500 femtosecond pulses with 15 ns pulses. In this paper, the effects of laser wavelength (355, 532,
and 1064 nm) and laser pulse duration (in the range of 8 to 200 ns) are investigated. Furthermore, the effects of laser
pulse energy, intensity, and focal spot size are studied. The printed droplet volume, hydrogel jet velocity, and cell via-
bility are analyzed.
Keywords: bioprinting, laser-assisted bioprinting, laser-induced forward transfer, laser absorption layer, laser paramet-
ric study

*Correspondence to: Lothar Koch, Laser Zentrum Hannover e.V., Nanotechnology Department, Hollerithallee 8, 30419 Hannover, Germany;
Email: l.koch@lzh.de

Received: October 1, 2016; Accepted: November 25, 2016; Published Online: January 25, 2017
Citation: Koch L, Brandt O, Deiwick A, et al., 2017, Laser-assisted bioprinting at different wavelengths and pulse durations with a
metal dynamic release layer: A parametric study. International Journal of Bioprinting, vol.3(1): 42–53.
http://dx.doi.org/10.18063/IJB.2017.01.001.

1. Introduction pulsed laser evaporation direct-write (MAPLE-DW)).
P substrate is usually coated with a thin layer of laser-
For laser-assisted bioprinting (LaBP), a transparent
rinting of proteins, living cells and tissue is a
rapidly growing scientific field. Different print-
absorbing material and a second thicker layer of bio-
ing techniques are applied, mainly extrusion
techniques (also called robotic dispensing or sy- material, typically a hydrogel with embedded cells,
to be printed. Laser pulses are focused into the laser-
ringe based techniques), ink-jet printing, and laser- absorbing layer, sometimes called Dynamic-Rel-
assisted bioprinting (also called biological laser print- ease-Layer (DRL), which is vaporized in the focal
ing, laser-induced forward transfer, or matrix-assisted region, generating a vapor bubble (Figure 1). This

Laser-assisted bioprinting at different wavelengths and pulse durations with a metal dynamic release layer: A parametric study. © 2017 Lothar Koch,
et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License
(http://creativecommons.org/licenses/by-nc/4.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the
original work is properly cited.
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