Fig. 4. Surfaces and mechanical properties of printed structures.

(A to C) SWLI of a printed silicone surface shows a surface roughness of 150 nm [2D scan (A), slice along the x axis (B), and slice along the y axis (C)]. (D) Stress-strain curve of printed silicone dog-bone specimens; printed silicone structures are capable of enduring more than 700% strain before mechanical failure. Tensile tests maintain a linear stress-strain relationship at low strains (inset). (E) Scanning electron microscopy of the cross section of a printed silicone structure demonstrates the uniformity of printed structures. (F) Macrophotographic image of a dog-bone specimen printed from silicone elastomer for tensile testing. (G) Macrophotographic images of printed dog-bone structures in the relaxed and highly strained states.