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International Journal of Bioprinting 3D printed substrate for adhesion tests

Figure 8. Marketed Salonpas patch adhesion test. Effect of substrate material on adhesion properties. (a) Probe tack test of Salonpas patches displays
significantly lower peak adhesive force for PP probes compared to SS probes. (b) Peel adhesion test of Salonpas patches displays significantly lower peel
force for PP plates compared to SS plates. Results are expressed as mean ± standard deviation (n = 3). ****p < 0.0001; *p < 0.05.

Our preliminary study also suggests that deformations Furthermore, utilizing human cadaver skin can be costly
(unevenness or holes on the surface) affect the contact and is thus not a cost-effective option. 35,41,44–47 PP probes
angle measurement of polar (water) and non-polar and skin (adhered to the SS probe) displayed a significant
(diiodomethane) solvents, resulting in variations in SE reduction (p < 0.001) in peak adhesive force compared to
measurements. Therefore, evaluating the SE of the probe the SS probe (SE > 700 mN/m), strongly suggesting that
surface is crucial to confirm its lack of deformations. Our the SE of a probe surface substantially affects the peak
SE measurements revealed that PP probes did not exhibit adhesive force. Additionally, our peel adhesion test results
any significant difference between the measured (34.62 indicated significantly lower peel adhesive force for the PP
mN/m) and reported SE values (29 mN/m), inferring plate compared to the SS plate.
that the SE of PP probes is similar to that of human skin
(25–56 mN/m). 39 Similar observations were also reported by Kowalski et
al., who studied tack properties of acrylic PSAs crosslinked
Probe tack test results displayed no significant
differences between PP probes and skin (adhered to SS with PE, PP, polytetrafluorethylene, SS, glass, PC, and
probe surface), suggesting that PP probes mimicked the poly(methyl methacrylate). They observed that as the SE
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SE of the skin. Moreover, significantly high variations were of a material increases, the tack property also increases.
observed in the probe tack test results for skin adhered to Although they demonstrated the relationship between tack
the SS probe compared to PP probes. This could be due and SE, they did not study various types of FDA-approved
to difficulties in consistently attaching the skin to the SS PSAs, including silicone-based PSAs commonly used in
probe during each tack test and the dryness of the skin. marketed transdermal patches. Moreover, they modified
Additionally, the characteristics of the skin’s surface can the PSAs via crosslinking with different materials and
differ based on factors such as age, race, and gender. 33,40–43 studied the tack properties of these modified adhesives.

Volume 10 Issue 4 (2024) 526 doi: 10.36922/ijb.3735