Structure and properties of polytetrafluoroethylene (PTFE) fibers were characterized thoroughly by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analyzing (TG) and water contact angle measurement. It was found that the longitudinal surface of the fiber was not smooth and was full of grooves. The cross sections of fibers were sheet-like and irregular. The infrared spectrum of PTFE fibers was the same as that of PTFE films except the 626 cm ^-l bands which were associated with the helix-reversal defect. The range of fineness distribution (2.09–11.50 dtex) was wide and the average strength was 1.37 cN/dtex. PTFE fibers began to be decomposed at 508.6°C and showed excellent thermal stability. The water contact angle of fibers layers was 120° indicating it to be a hydrophobic material. All these results provide a theoretical foundation for applications of PTFE fibers.

Electronic skins with deep and comprehensive liquid information detection are desired to endow intelligent robotic devices with augmented perception and autonomous regulation in common droplet environments. At present, one technical limitation of electronic skins is the inability to perceive the liquid sliding information as realistically as humans and give feedback in time. To this critical challenge, in this work, a self-powered bionic droplet electronic skin is proposed by constructing an ingenious co-layer interlaced electrode network and using an overpass connection method. The bionic skin is used for droplet environment reconnaissance and converts various dynamic droplet sliding behaviors into electrical signals based on triboelectricity. More importantly, the two-dimensional sliding behavior of liquid droplets is comprehensively perceived by the e-skin and visually fed back in real-time on an indicator. Furthermore, the flow direction warning and intelligent closed-loop control of water leakage are also achieved by this e-skin, achieving the effect of human neuromodulation. This strategy compensates for the limitations of e-skin sensing droplets and greatly narrows the gap between artificial e-skins and human skins in perceiving functions.

The cattail fiber assembly used as a sorbent for the sorption of engine and vegetable oils was investigated. The internal factors governing the oil sorption of cattail fibers were discussed. The analysis for the adsorption mechanism of cattail fiber assembly indicated that the tuft of cattail fibers has a down-like structure and, thus, its surface area and retaining space are large. The high surface waxiness and small surface free energy enabled the cattail fiber to have excellent oleophilic–hydrophobic property. The experimental results indicated that the oil-sorption rates of cattail fiber assemblies to engine oil and vegetable oil were 13.4 g/g and 14.6 g/g, respectively, and the oil retention capability to both engine oil and vegetable oil after 24 hours was over 95%. The cattail fibers have similar oil sorption capability with those of nonwoven wool materials, however, nature sorbents such as kapok fibers are superior to the cattail fibers.