Photo-responsive droplet manipulation slippery lubricant-infused porous surface with ultra-high durability

Photo-responsive slippery lubricant-infused porous surface(SLIPS) for droplet manipulation is flexible, noncontact and non-destructive in droplet manipulation, which has promising applications in flexible robotics, microfluidics,biomedicine, and chemical analysis. However, the repeated manipulations for droplets of SLIPSs are quite limited in the works reported so far, the poor durability of droplet manipulation severely limits the practical application of the surfaces. In this paper, an Fe3O4-doped polydimethylsiloxane(PDMS)-based SLIPS is proposed and implemented to achieve ultra-high repeated droplet manipulation numbers under near-infrared ray(NIR) laser irradiation. Firstly, a micron columnar array structure with micro-pits on the top side, as well as, a wall structure out of the array is designed on SLIPS to reserve the lubricant. Secondly, the prototype of the SLIPS is fabricated by a 3-step ultraviolet(UV) lithography, and subsequently immersed in silicone oil for more than 96 h to obtain the ultra-high durability slippery lubricant-infused porous surface(UD-SLIPS). With a power of 25 m W–85 m W NIR laser, the repeated manipulation of microdroplets(≤ 5 μL) in the scale of 1 cm can exceed more than 3000 times which is far beyond that in previous reports. Finally, the droplet manipulation performance of this photo-responsive UD-SLIPS and the influence of infusion time on durability are investigated. The mechanism of the PDMS swelling effect is found to be the key factor in improving the droplet manipulation durability of SLIPS. The findings of this work would be of great significance for the development of highly durable photo-responsive functional surfaces for droplet manipulation.

Long-term deterioration of lubricant-infused nanoporous anodic aluminium oxide surface immersed in NaCl solution

This study investigated the deterioration of a lubricant-infused anodic aluminium oxide surface in a 1M NaCl solution for~200 days.Direct observation by cryo-SEM and quantitative analyses by UV spectroscopy and EIS revealed that the long-term deterioration of the lubricant-infused surface was divided into two stages:the surface-adhered lubricant layer gradually dissolved at a constant rate until the substrate was exposed;afterwards the lubricant infused in the nanochannels began to diffuse and was depleted after~200 days.The EIS results also revealed that the defects reduced the corrosion resistance of the lubricant-infused surface considerably.

Recent advances in slippery liquid-infused surfaces with unique properties inspired by nature

The slippery liquid-infused porous surface(s)(SLIPS)that imitates the Nepenthes pitcher plant has proven to be highly versatile and can be combined with various surface characteristics such as dynamic response,antifouling,selective adhesion,and optical/mechanical tunability.In addition,the introduction of a lubricating fluid layer also gives it extremely low contact angle hysteresis and self-repairing properties,which further expands its application range.Currently,SLIPS has been proven to be suitable for many frontier fields such as aerospace,communications,biomedicine,and microfluidic manipulation.In this review,we explain the theoretical background of SLIPS and the preparation methods currently available,including the choice of substrate materials and lubricants,and we discuss the design parameters of the liquid injection surface and how to deal with the consumption of lubricants in practical applications.In addition,the paper focuses on current and potential applications,such as preventing pathogen contamination of and blood adhesion of medical equipment,manipulation of tiny droplets,and directional transportation of liquids.Finally,some weaknesses that appear when SLIPS is used in these applications are pointed out,which provides a new perspective for the development of SLIPS in the future.

Lubricant skin on diverse biomaterials with complex shapes via polydopamine-mediated surface functionalization for biomedical applications

Implantable biomedical devices require an anti-biofouling,mechanically robust,low friction surface for a prolonged lifespan and improved performance.However,there exist no methods that could provide uniform and effective coatings for medical devices with complex shapes and materials to prevent immune-related side effects and thrombosis when they encounter biological tissues.Here,we report a lubricant skin(L-skin),a coating method based on the application of thin layers of bio-adhesive and lubricant-swellable perfluoropolymer that impart anti-biofouling,frictionless,robust,and heat-mediated self-healing properties.We demonstrate biocompatible,mechanically robust,and sterilization-safe L-skin in applications of bioprinting,microfluidics,catheter,and long and narrow medical tubing.We envision that diverse applications of L-skin improve device longevity,as well as anti-biofouling attributes in biomedical devices with complex shapes and material compositions.

Electron transfer dominated triboelectrification at the hydrophobic/slippery substrate-water interfaces

Triboelectric nanogenerator(TENG)based on triboelectrification has attracted wide attention due to its effective utilization of green energy sources such as marine energy.However,researches about liquid-liquid triboelectrification are still scanty as solid-liquid triboelectrification has been widely studied.Herein,this work focuses on the hydrophobic/slippery substrate-water interfacial triboelectrification based on the solid friction materials of polytetrafluoroethylene(PTFE)nanoparticles.The hydrophobic/slippery substrate-water interfacial triboelectrification are studied by assembling PTFE coated Al sheets and perfluoropolyether(PFPE)infused PTFE coated Al sheets(formed the slippery lubricant-infused surfaces(SLIPSs))as the friction electrode,and water as liquid friction materials,respectively.The results show that the hydrophobic TENG output performances improved as the PTFE nanoparticles cumulating,and the SLIPSs TENG output performances increased with the thinner PFPE thickness.Both the triboelectrification behavior of hydrophobic/SLIPSs TENG assembled in this work are dominated by the electron transfer.Thanks to the introduction of SLIPSs,the SLIPSs TENG exhibits superior stability and durability than the hydrophobic TENG.The investigation of hydrophobic/slippery substrate-water interfacial triboelectrification contributes to optimize the TENG performances,and expands the application in harsh environments including low temperature and high humidity on the ocean.