Biomedical Engineering Reference
In-Depth Information
VALVE
COMPRESSED AIR
DISPENSER
FAN
HEAT SINK
HEAT PIPE
HYDROGEL
PELTIER
DEVICE
MIST
SPRAY
NOZZLE
3D PLATFORM
HEATER
PC
Fig. 9.6
Schematic illustration of an extruding/aspiration patterning set-up. The main difference
with other nozzle-based systems is established through the incorporation of a mist spray, thus
preventing desiccating of the fabricated constructs
enables switching between the modes. In a closed configuration, compressed air is
supplied to the nozzle and the hydrogel is extruded onto the substrate, or refilled
into the aspirated groove. By opening the valve, the compressed air is directed
through the valve, and the hydrogel solution is aspirated by Bernoulli suction. To
prevent desiccating (to maintain the viability of the cells), a mist spray is used to
create a supersaturated atmosphere inside the box.
The most recent trend is the use of hydrogel systems and cell encapsulation strat-
egies to fabricate gel/cell hybrid constructs [
189-
195
]. The 3D-Bioplotter and other
similar techniques can be seen as the most straightforward hydrogel/cell manufac-
turing method for designing complex inner and outer architectures, without the need
for an additional support structure. In some cases, the developed machine contains
multiple nozzles with different designs (sometimes even printer-based). In litera-
ture, “Cell Assembler” and “Bioassembly Tool” are commonly found machine
names that have a similar working principle. Work of Chang et al. [
196
] examined
the effect of nozzle pressure and size on cell survival and functionality. A quantifiable
loss in cell viability was seen, which was caused by a process-induced mechanical
damage to cell membrane integrity. It was suggested by the authors that cells might
require a recovery period after manufacturing.
9.3.2.2
Current Limitations and Hydrogel Feasibility
for Nozzle-Based Systems
An overview of the combination nozzle-based systems/hydrogel materials is sum-
marized in Table
9.2
. Lately, cell encapsulation strategies have been frequently
Search WWH ::
Custom Search