FIGURE 4.

Illustration of how a cyanoacrylate liquid skin protectant (CLSP) which is substantially stiffer than skin tissue reduces the coefficient of friction and thereby, the frictional forces and surface shear stresses applied to skin tissue. Consider a stiff medical device or object with a microscopic surface roughness as seen in, A, which comes into contact with bare skin. The stiff object causes microscopic deformation of the skin and, at locations of asperities, may indent the skin, which then increases the effective contact area of the micro‐topography of the said object with the skin. Frictional forces and shear stresses will therefore apply through these enlarged localised contact areas (marked by dashed white lines at the three circled contact sites). If, however, the same stiff object micro‐topography is encountered by a smoother surface which is also substantially stiffer than skin tissue, that is, the polymerised CLSP coating which does not deform as much when the asperities of the object push against it, then the effective (aggregate) localised contact area is reduced substantially, B. As a result, the overall frictional forces and surface shear stresses, which correlate with the effective contact area, decrease correspondingly