Page 526 - IJB-10-4

International Journal of Bioprinting 3D printed substrate for adhesion tests

and the patches were evaluated via probe tack and peel liner, with dry coat weights of 5 ± 0.25, 10 ± 0.5, and
adhesion testing. Furthermore, the novel 3D-printed 15 ± 0.75 mg/cm . The adhesives were then dried at 90°C
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probe/plate was used to evaluate the adhesion properties of for 30 min in the oven. The dried release liner was then
the marketed Salonpas patch. Fused deposition modeling kept at room temperature for 5 min before laminating with
(FDM) was selected as the 3D printing method due to a backing membrane using the JM18 laminator. Adhesives
its affordability and the wide range of FDA-approved were also laminated manually on glass slides. Adhesive
2
compatible polymers it utilizes. The FDM process patches of 0.79 cm were then cut and weighed to confirm
involves extruding a filament of molten polymer through the weight of dried adhesive on the release liner (Figure S1,
a precisely controlled nozzle according to a computer- Supporting Information).
generated program to print the desired structure layerwise.
FDM is a widely used cost-effective 3D printing technique 2.3. 3D printing and post-processing of probes
for developing personalized medical devices, utilizing The Standard Tessellation Language (STL) file (Figure 1a)
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various thermoplastic materials and large build areas of the probe with similar dimension as stainless steel probe
for specific user requirements. Nonetheless, FDM 3D (Figure 1c) (diameter: 7 mm; radius: 1˝) was first created
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printing features limited printing resolution and the using Autodesk Fusion 360 software.
inability to accommodate complex geometries compared 2.3.1. Printing temperatures
to light-based printing methods (e.g., stereolithography A critical challenge encountered during the optimization
[SLA] and digital light processing [DLP]). To address of 3D printing parameters for probe fabrication was
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these limitations, we meticulously optimized the printing thermally induced dimensional instability or warping.
parameters and employed additional post-processing Successful probe production necessitated meticulous
techniques. This approach ensures that the probes achieve control over a complex interplay between the printing
the desired surface morphology, essential for mimicking chamber and the build platform temperatures. Multiple
the roughness of human skin. probes were printed at different parameters, i.e., (i) 60°C
chamber with a 0°C build platform, (ii) 100°C chamber
2. Material and methods with a 0°C build platform, (iii) 80°C for both the chamber
2.1. Materials and build platform, and (iv) 70°C chamber with a 90°C
Polypropylene (PP) filaments were obtained from Braskem build platform (Table S1, Supporting Information).
(United States of America [USA]). Silicone-based PSAs, 2.3.2. Layer thickness
including PSA-4501, PSA-4502, PSA-4602, PSA-4202, To evaluate the effect of layer thickness on probe print
PSA-4301, and PSA-4302, were gifted by DuPont (USA). A quality, probes were printed at layer thicknesses of 30, 50,
texture analyzer (TA.XTPlus) and a TA-57R SS probe were 100, and 200 µm with optimized print parameters, i.e.,
purchased from Texture Technologies Corp. and Stable 70°C chamber temperature, 190°C nozzle temperature,
Micro Systems, Ltd. (USA). Ethyl acetate was obtained and 90°C platform temperature. The probes were also
from Sigma-Aldrich (USA). An Elcometer 3580/1 casting observed for warping (Table S2, Supporting Information).
knife film applicator (width: 50 mm) was obtained from
Elcometer Inc. (USA). The JetMounter JM18, an electric 2.3.3. Print orientation
18˝ pressure-sensitive cold mount laminator, was procured Probes were printed in horizontal and vertical orientations
from My Binding LLC (USA). Scotchpak™ 9735, 9733, and with optimized printing parameters, i.e., 70°C chamber
9723 Backing Polyester Film Laminates and Scotchpak™ temperature, 190°C nozzle temperature, 90°C platform
9744 Fluoropolymer-coated Release Liner were gifted by temperature, and 200 µm layer thickness.
3M (USA). The Dremel printer was procured from Dremel
(USA), and the MethodX 3D printer was obtained from 2.3.4. Post-processing optimization
Makerbot (USA). A Veeco Dektak 150 diamond probe The optimized PP probes (Figure 1b) were post-processed
surface profilometer was obtained from Bruker (USA). for different durations (i.e., 1 and 2 min) to optimize the
Salonpas pain relief patches (six patches; 14.4 × 9.2 cm) post-processing time and match the roughness of the skin.
were obtained from Hisamitsu America Inc. (USA). Post-processing optimization was performed using an
automated setup that includes a robotic arm (Lynxmotion
2.2. Adhesive coating smart servo [LSS] Arm; RobotShop, VT, USA); a probe
To evaluate the adhesion properties of PSA coating, mount to mount the probe on the stepper motor; and a
silicone-based amine- and non-amine-compatible PSAs, stepper motor to rotate the probe along the probe sander
including PSA-4102, PSA-4302, PSA-4202, PSA-4501, for probe-surface smoothening (Figure 1d). Briefly, the
PSA-4502, and PSA-4602, were coated onto the release probe was mounted on the probe mount; the probe sander

Volume 10 Issue 4 (2024) 518 doi: 10.36922/ijb.3735