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3D printed fabric silicone composite
A C

D

B

E

Figure 2. Schematic of workflow and production process of additively manufactured silicone inserts:
Three-dimensional (3D) scanned geometry of (A) hypertrophic scars (HS) with refined insertion models
and (B) hand with refined web insertion models. Photo of 3D printed: (C) Insertion for the HS; (D) and
(E) web insertion for webspace between second and third digits; Scale bar: 10 mm.

materials. After that, the 3D models were refined, of pressure at the interface between the scar and
and the model orientation was adjusted for printing. garment for effective scar reduction by combining
Finally, the 3D models were imported into the 3D- and reinforcing the pressure, hydration, and static
printer (3D-Bioplotter Manufacturer Series) for electricity stimulation together .
[17]
®
the additive manufacturing process. Figure 2C-E is
the photo of the silicone inserts which can function 3.2 Mechanical performance of fabricated
as orthoses to prevent web space contractures composites
during therapy [17,33] . When comparing the 3.2.1 Adhesion force
traditional manual insert material production and
the 3D printing process, the 3D printing production To achieve an additive manufactured product with
process minimizes human errors in orthosis design high resolution, a print silicone mixture with high
and achieves a reliable and repeatable geometry of viscosity needs to be used. However, high viscosity
inserts. Once the silicone insert was 3D printed on silicone mixtures do not easily diffuse through
fabric, it could be sewn as a part of the pressure fabric; hence, resulted in poor shear strength of
garment to increase pressure onto the specific body the 3D printed silicone and fabric. To prevent the
region and prevent the distal migration of scars. pressure garment fabric and 3D printed silicone
For silicone gel sheet therapy, the planar shape of inserts from separating during wearing, a multi-
silicone gel sheet is usually larger than the size of material printing approach was adopted to improve
HS regardless of the 3D body shapes and curvatures, the force of the adhesion. The schematic of this
thus leading to displacements, ill-fitting, and approach is shown in Figure 4. During the printing
discomfort during the treatment, Figure 3A and B. process, a lower viscosity (around 7400 Mpa·s)
When comparing with silicone gel sheet therapy, silicone mixture was used in the first printed layer,
the accurate geometric shape of the printed silicone while a higher viscosity (around 1,080,000 Mpa·s)
inserts prevents negative impacts such as excessive silicone mixture was used in the other printed
sweating, pruritus, and contact dermatitis of the layers. The viscosity curve of the silicone print
healthy skin next to the HS, Figure 3C. Moreover, mixtures with different thickener contents at 0°C,
the silicone inserts can administer the right amount which is the temperature of the print head, as a

74 International Journal of Bioprinting (2020)–Volume 6, Issue 2