Existing separation technologies struggle to recover oil and water concurrently from surfactant-stabilized emulsions to achieve the goal of near-zero liquid discharge. We present a Janus channel of membranes (JCM) that features a confined architecture constructed of a pair of hydrophilic and hydrophobic membranes, which allows for concurrent, highly efficient recovery of oil and water from surfactant-stabilized emulsions. The confined Janus channel can amplify the interplay of the membrane pair through a feedback loop that involves enrichment and demulsification. Our JCM achieves exceptional oil and water recoveries of up to 97 and 75%, respectively, with near 99.9% purities. Moreover, its versatility in handling diverse emulsions may enable near-zero liquid discharge for a range of separations.

Spatiotemporally controllable droplet manipulation is essential in diverse applications, ranging from thermal management to microfluidics and water harvesting. Despite considerable advances, droplet manipulation without surface or droplet pretreatment is still challenging in terms of response and functional adaptability. Here, a droplet ultrasonic tweezer (DUT) based on phased array is proposed for versatile droplet manipulation. The DUT can generate a twin trap ultrasonic field at the focal point for trapping and maneuvering the droplet by changing the position of the focal point, which enables a highly flexible and precise programmable control. By leveraging the acoustic radiation force resulting from the twin trap, the droplet can pass through a confined slit 2.5 times smaller than its own size, cross a slope with an inclination up to 80°, and even reciprocate in the vertical direction. These findings provide a satisfactory paradigm for robust contactless droplet manipulation in various practical settings including droplet ballistic ejection, droplet dispensing, and surface cleaning.

With the increasing concern of energy crisis and global warming, the whole globe is in an urgent need to develop clean energy that comes from renewable sources and does not harm the environment to fulfill the carbon neutralization and green earth commitments. Water is the most abundant substance on earth and has been historically used as the major energy carriers in watermill, water wheel, and hydroelectricity. Moisture electricity generation is another emerging technology that can convert low-grade energy in the widely-accessible moisture to electricity simply by the integration of moisture, electrodes, and deliberately-designed hygroscopic films. Recent research on moisture electricity generators (MEGs) led to the creation of a series of self-powered sensors and in some occasions they have replaced conventional batteries to power miniaturized devices. In this review, the basic mechanisms of MEGs are firstly clarified, and three categories of them, i.e., gradient structure, homogeneous structure, and heterogeneous structure depending on the structure of hygroscopic films, are then introduced. Furthermore, recent advances in the fabrication, characteristics, and performance of MEGs are summarized, and MEGs with continuous or transient output that could be applied in self-powered sensors and power sources are discussed. Finally, some remaining challenges and our perspectives on MEGs are highlighted.