Oil-triggered switchable wettability on patterned alternating air/lubricant-infused superamphiphobic surfaces†
In the present study, we report a novel oil-triggered surface (OTS) by integrating three extreme states of hydrophobicity, i.e., ‘lotus-leaf-like’ superhydrophobicity, ‘nepenthes-like’ slippery liquid-infused surface hydrophobicity and ‘re-entrant-structure-induced’ superamphiphobicity. The OTS is fabricated by an ultra-fast laser based technology through creating alternating gas/oil infused superhydrophobic–superoleophilic micro-nanostructures among superamphiphobic micro-nanostructures. We demonstrate that the precisely arrayed superhydrophobic–superoleophilic micro-nanostructures can be reversely switched quickly to be in a ‘lotus-leaf-like’ gas-infused or ‘nepenthes-like’ oil-infused state through an oil-triggered method. The test droplets can slide with freedom on gas-infused superhydrophobic–superoleophilic patterns while they will be confined, guided or self-driven by oil-infused ones. Especially, the droplets can move along oil-infused patterns with a high mobility, but without pinning, liquid loss or cross contamination. The surfaces are further used as droplet-manipulation chips to attest real-time operating ability, on which the test droplets can be selectively ‘trapped’, ‘guided’, ‘directed’, ‘pumpless-moved’, ‘pumpless-dragged’, ‘pumpless-pulled’ and ‘pumpless-pushed’ in real time through the remote control of the oil-triggered method. In addition, our OTSs manifest a remarkable long-time stability of >80 days and cycle-to-cycle stability of >10 cycles. With multiple functions and various superior abilities, the OTSs have expansive application prospects. Especially, the oil-triggered strategy and laser-based technology proposed here may aid the development of various fields related to liquid manipulation and smart switchable surfaces.