Ridged Zn/PDMS smart surface with wide-range reversible wettability and high sensitivity responsive to mechanical strain

Smart surfaces with dynamically tunable wettability place an important role in microfluidics, biomedical engineering and flexible electronics. Mechanical strain is a promising stimulus to tune the surface wettability, however, it is still a great challenge to achieve both wide-range reversible wettability and high sensitivity. In this study, highly ordered and quasi-periodic ridge patterns with cracks at their peaks were tailored based on a film-substrate system by sputter deposition of zinc (Zn) nanofilm on prestretched polydimethylsiloxane (PDMS). The contact angle (CA) on the ridged Zn/PDMS surface is well tunable between 115° and 143° by adjusting the applied strains. It is remarkable that such a structure possesses wide-range CA variation (~28°) under just 28.6% applied strain, indicating a high responsive sensitivity (η = 98°). This result is attributed to the cracked ridges with both wide-range aspect ratios from 0.07 to 0.54 and high rate of change (~1.70). Moreover, the responsive reversibility of the ridged Zn/PDMS surface remains up to 1000 cycles and 60 days without special protection. The outstanding performances make the ridged surface could be a promising component for various technological applications, especially in small strain required situations. [Display omitted] •Low cost and biocompatible materials (zinc and polydimethylsiloxane) are chosen to design the smart surface.•A novel structure is tailored on the smart surface, namely cracked ridges.•The ridged smart surface possesses wide-range reversible wettability and high sensitivity responsive to mechanical strain.•The wetting mechanism on the ridged smart surface is investigated.