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3D printed fabric silicone composite
silicone sheet therapy provides a more effective
result in reducing the scar thickness. Since the
amount of pressure induced by a pressure garment
also depends on the mechanical properties of the
fabric, the influence of 3D printed silicone gel on
the mechanical behavior and tension decay after
repeated extensions of the warp-knitted fabric used
for pressure therapy garments was also determined
to provide new insights into the wider application
of 3D printing, such as clinical applications,
flexible electronics and wearable products, and
development of soft robotics and actuators.
2 Materials and methods
2.1 3D modeling and fabrication
The geometry of the hands of a patient with HS
was obtained using a structured light handheld 3D
scanner (Artec Eva, Luxembourg). After scanning
was completed, the scanned images were registered
using Artec Studio 13. The registered point cloud
data were then imported into processing software
(Materialise Magics) and converted into 3D mesh
models for the fabrication process. The models for
printing were based on the amount of redness and
protrusion of the HS and point cloud data. After
obtaining the desired models, the model meshes
and coordinates were adjusted with reference
to the required orientation and dimensions of
silicone gel, as well as the method of garment
prototyping before the fabrication process took
place.
Warp knitted fabric made of a blend of nylon
(83%) and spandex (17%) with a total weight of
165 g/m and 0.226 mm in thickness, which is the
2
typical type of fabric used for pressure therapy
garment, was applied as the reinforcement of
the composite. In consideration of the adhesion
of the fabric and printed silicone gel, two print
mixtures with two different viscosities were
prepared. A biocompatible silicone elastomer
(SILBIONE RTV 4410 1:1 A and B) was mixed
®
with 0.2 and 2 wt% of a silicone thickener
(THI-VEX ), respectively, and degassed for
TM
3D printing onto the fabric. The 3D printing was
carried out using a 3D-printer (3D-Bioplotter
®
Manufacturer Series) and the settings and
72 International Journal of Bioprinting (2020)–Volume 6, Issue 2
printing toolpaths are shown in Table 1 and
Figure 1, respectively.
To characterize the mechanical properties of
the printed composite, the samples were additively
manufactured at 20 × 100 × 2.24 mm for cyclic
tensile testing, the size stated in ASTM D5169
Standard Test Method for Shear Strength (Dynamic
Method) of Hook and Loop Touch Fasteners and
ASTM D638-14 Standard Test Method for Tensile
Properties of Plastics (Type V specimens) to test the
adhesive force and tensile properties, respectively.
The adhesive behavior of three different samples
was evaluated. The 3D printing parameters of the
samples are listed in Table 2. Note that, pigment
was added into the print mixture for visualization
and surface morphology investigation purposes,
and no pigment was added to the samples for the
mechanical characterization. Furthermore, the
surface morphology of the ASTM D5169 samples
was observed using an optical microscope.
Table 1. Parameters of different print mixtures of
3D-Printing process.
Print mixture SILBIONE RTV 4410 1:1 A
®
and B+0/0.2/.2.0 wt% THI-
VEXTM
Nozzle diameter (mm) 0.4
Printing speed (mm/s) 20
Build Platform 70
temperature (°C)
Head temperature (°C) 0
Path width (mm) ~0.6
Inner structure pattern(°) 0,90
3D: Three-dimensional
Figure 1. 3D printing toolpath.