Universal liquid self-transport beneath a flexible superhydrophilic track

Abstract

Spontaneous liquid transport on an open surface offers a great opportunity to develop advanced systems with lower energy consumption and multifunction. Achieving universal liquid self-transport via a simplified carrier is highly desirable for fluid-controlling interfaces. Here, we present liquid self-transport beneath a flexible superhydrophilic track for versatile liquid manipulation. The capillary effect generated from the sandwiched channel drives directional liquid spreading with a speed ranging from 0.3 to 5 mm/s, which depends on the wettability and roughness of the paired substrates. Through the structural design and integration of channels, a series of applications such as pumpless microfluidic chips, interfacial evaporators, and portable electrolysis microchips have been demonstrated. We envision that this self-propelled liquid channel, with its extremely simple structure and high adaptability, will meet the requirements for efficient mass transfer and open new avenues for improving current systems in the fields of heat transfer, liquid harvester, microfluidics, etc.