Biomedical Engineering Reference
In-Depth Information
2.2.3
LASER-INDUCED FORWARD TRANSFER
Laser-induced forward transfer (LIFT) (
Koch et al
.
, 2009, 2012; Gruene et al., 2010
) mainly employs
a high-powered pulse laser and two coplanar glass slides. The experimental setup is described in
Figure 2.3
. The upper slide, called “donor-slide”, is coated with an energy absorption metal layer
and a layer of material containing cells. Laser pulses are focused on the metal layer via the glass
slide, evaporating the laser absorbing layer locally. During the process, the laser pulse generates a
high gas pressure that transfers the underlying cell compound toward the lower slide, referred to as
“collector-slide.” The biological materials containing cells are usually a culture medium or hydrogel
that provides a humid environment, thus preventing cell dehydration. Hydrogel has the additional
function of sustaining cell structure.
2.2.4
MATRIX-ASSISTED PULSED LASER EVAPORATION DIRECT WRITING
The setup of matrix-assisted pulsed laser evaporation direct writing (MAPLE DW) (
Ringeisen et al.
,
2004;
Patz et al
.
, 2006; Doraiswamy et al
.
, 2007
) is similar to the LIFT system shown in
Figure 2.3
. Instead
of using a glass slide for the “donor-slide,” MAPLE DW employs an optically transparent quartz sup-
port called “ribbon.” The ribbon is coated with biological materials, such as Matrigel
®
or bioceramic.
The biomaterials with cells are referred to as “matrix”. The substrate, similar to the “collector-slide”,
may or may not be covered with hydrogel. Laser is focused on the interface of the quartz support and
a laser-absorptive layer containing cells. The laser beam causes evaporation of part of the biomaterial
layer, which generates gas bubbles locally. The gas bubbles result in the release and propulsion of the
cell-seeded matrix to the receiving substrate.
FIGURE 2.3
A schematic of LIFT (
Gruene et al.
,
2010; Koch et al.
,
2012; Ringeisen et al.
,
2004
).
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