Fig. 8. Scanning electron microscopy images showing the strong bonding of Si ribbons with PDMS. When the extreme strain is applied to Si/PDMS sample, the Si ribbons are still attached and maintained their wavy shape to/on PDMS even after breakage. a Inset clearly shows cohesive failure of PDMS.

Fig. 9. Sequential optical microscopy images showing that the wave peaks (valleys) do not move along the surface to accommodate the applied strain. Note that the ring-shaped Si fragment (generated by lithographic defect) served as a marker and was used to track the lateral movement of materials involved, Si and PDMS. (Scale bars: 20 mm.)

Fig. 10. Experimental evidence of negligible membrane strain in buckled, thin (100 nm) Si film.

Fig. 11. (a) Three-dimensional total energy landscape of Si/PDMS buckling system, as a function of wavelength and amplitude. (b) Total energy as a function of wavelength for given values of prestrain and amplitude.