Figure 4.

Analysis and optimization of the dimensions of the cavities. a-b) Schematic illustrations of a) a liquid-filled cavity with a device mounted on the skin and b) its collapsed state under a stretching deformation. c) Critical normalized work of adhesion (${\stackrel{‒}{\gamma }}_c$) versus normalized initial length (L/a) for fixed elastic properties and initial thickness under 0%, 20%, and 50% stretching. d) Minimum total initial thickness (h_min +t) versus the thickness of the top layer of elastomer (Ecoflex, t). e-f) Interfacial stresses between human skin and the device under 30% stretching for the case of a 10 mm-long device with several cavity lengths – e) shear stress and f) normal stress as a function of position.