Stimuli-responsive surfaces for switchable wettability and adhesion

Diverse unique surfaces exist in nature, e.g. lotus leaf, rose petal and rice leaf. They show similar contact angles but different adhesion properties. According to the different wettability and adhesion characteristics, this review reclassifies different contact states of droplets on surfaces. Inspired by the biological surfaces, smart artificial surfaces have been developed which respond to external stimuli and consequently switch between different states. Responsive surfaces driven by various stimuli, e.g. stretching, magnetic, photo, electric, temperature, humidity and pH, are discussed. Studies reporting on either atmospheric or underwater environments are discussed. The application of tailoring surface wettability and adhesion includes microfluidics/droplet manipulation, liquid transport and harvesting, water energy harvesting and flexible smart devices. Particular attention is placed on the horizontal comparison of smart surfaces with the same stimuli. Finally, the current challenges and future prospects in this field are also identified.

Automated summary

This review categorizes different contact states of droplets on surfaces based on their wettability and adhesion properties, inspired by diverse unique surfaces found in nature. Smart artificial surfaces that respond to various stimuli and can switch between different states are discussed, along with their applications in areas such as microfluidics, liquid transport, water energy harvesting, and flexible smart devices. Current challenges and future prospects in this field are also highlighted.