Significance: Driving liquid microdroplets has been challenging due to the large contact angle hysteresis and insufficient driving force at microscale. We designed a strategy to directionally transport water and oil microdroplets. By simply mounting hydrogel dots on a slippery surface to arrest lubricant menisci, spontaneously formed capillary force pumps liquid microdroplets continuously at high efficiency. Such strategy is universally applicable to water and oil droplets of different surface tensions and different sizes, yet with little substrate preparation effort. Furthermore, we demonstrated its applications in highly efficient water droplet collection and biomedical sample enrichment for highly sensitive detection. Our technique may be useful in water harvesting, droplet condensation, and biomedical analysis.

By printing functional inks on the porous nanocomposites composed of polar and non-polar components, a couple of unique features were demonstrated on the developed multifunctional liquid-infused materials.