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. 2015 Oct 6;5:14787. doi: 10.1038/srep14787

Figure 4. Optical microscope images of oxygen plasma treated PDMS samples as a function of chromium/gold layer thickness.

Figure 4

(a) chromium/gold = 2 nm/100 nm. (b) chromium/gold = 5 nm/100 nm, the crack density N = 2.1 ± 0.3 × 107 m−2. (c) chromium/gold = 10 nm/100 nm, N = 1.3 ± 0.2 × 108 m−2. (d) chromium = 100 nm, N = 2.7 ± 0.5 × 109 m−2 (Scale bars = 300 μm). (e) plots of the mud-crack pattern mesa density N (log) versus oxygen plasma dose D and evaporated chromium thickness (log). (f) plots of the pattern size Lc (log) versus oxygen plasma dose and evaporated chromium thickness (log). (g) total crack length LT (per square meter) versus oxygen plasma dose and evaporated chromium thickness (log). The inset to (d) shows a zoom of the mud-crack patterning (scale bar = 30 μm). The red circles correspond to an oxygen plasma dose of 1.5 kJ – the blue square correspond to a Cr metallization thickness of 10 nm.