Reversible Bubble Transfer on a Bioinspired Tridirectionally Anisotropic Lubricant-Infused Surface

Underwaterbubble transfers on functional surfaces with specialwettability have important research value for many fields such aswater purification, gas-evolving electrochemistry, heterogeneous catalysis,etc. However, realizing multi-interface collaborated and multi-directionalbubble transfers are still challenging. Herein, inspired by butterflywings, pitcher plants, and rice leaves, we present a tridirectionallyanisotropic lubricant-infused surface (TALIS) with micro-nanohierarchical step-like structures that are covered with silicone oil.The TALIS exhibits significant tridirectional anisotropy in termsof bubble sliding, specifically, the slippery property parallel tothe grooves with an ultra-low bubble sliding angle (BSA) of & SIM;2 & DEG;,and the unidirectional wettability perpendicular to the grooves withBSA difference of & SIM;48 & DEG; result from the step-edge pinningeffect. By adjusting the step height and width, TALISs with differenttridirectionally anisotropic wettability and stable bubble-holdingefficiency (& SIM;0.4 mg/cm(2)) are obtained. In addition,horizontal and anti-buoyancy unidirectional bubble transfers are realizedby collaborative squeezing of two face-to-face TALISs. By adjustingthe distance between the two TALISs, bubbles can be reversibly transferredbetween the two interfaces by multi-interfaces collaboration. Thiswork opens a new avenue to understand the bubble behaviors on functionalinterfaces with anisotropic wettability and provides a method to realizecontrollable bubble transfer on multi directions.