Directional droplet/bubble transportation on slippery photothermal responsive laser-induced graphene/polyimide membrane

Abstract

Droplet and bubble manipulation on functional surfaces is a critical issue in numerous applications such as microreactor, microfluidic, biological, and gas transport. Despite recent efforts in tuning the physicochemical properties of responsive surfaces to impart functionalities in response to different external stimuli, it remains challenges to manipulate both the droplet and the bubble simultaneously on responsive surfaces. Here, we report an intelligent slippery laser-induced graphene/polyimide (SLIG/PI) membrane with excellent photothermal responsive property and superior oil absorption capacity. Through local near-infrared radiation (NIR) irradiation, we can simultaneously manipulate both the droplet and the bubble transportation on the SLIG/PI membrane in a controllable fashion. Owing to a dominant wettability gradient force, the antigravity droplet transportation and the antibuoyancy bubble movement can be simultaneously achieved on the inclined SLIG/PI surface. Moreover, both the droplet and the bubble can be steered to move on desirable traces by constructing the SLIG/PI membrane with programmable pathways. We envision that this work might provide important insights into the construction of intelligent devices for controllable droplet/bubble motion.