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.

A shape-reconfigurable,light and magnetic dual-responsive shape-memory micropillar array chip for droplet manipulation

Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering.However,most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation.Herein,we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets,oil droplets and water-in-oil droplets.Water-in-oil droplets provide an enclosed space for water droplets,preventing the evaporation in an open environment.Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance.The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer.The micropillars irradiated by a near-infrared laser bend under the magnetic force,while the unirradiated micropillars still keep their original shape.In the absence of a magnetic field,when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature,the micropillars return to their initial shape.In this process,the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.

Droplet Manipulation and Crystallization Regulation in Inkjet-Printed Perovskite Film Formation

Emerging organic–inorganic metal halide perovskite materials have become the focus of the optoelectronics research community owing to their excellent photoelectric properties.Nevertheless,challenges still exist for transferring the lab-made devices to largearea industrial modules.Inkjet printing(IJP)technology provides a promising way to fill the gap because of its precise droplet control and uniform large-scale deposition functions.Hence,an in-depth understanding of inkjet-printed perovskite films in terms of droplet manipulation and crystallization regulation is critical for upscaling the perovskite devices to commercial usage.In this review,we give an overview of inkjet-printed high-quality perovskite films and provide guidelines on inkjet-printing large-scale highperformance perovskite devices.First,we analyze theories of droplet formation and perovskite nucleation/crystallization dynamics and then focus on summarizing the perovskite film-formation strategies via IJP,in the aspects of ink engineering,the printing process,and posttreatment.Furthermore,we review the recent advances of inkjet-printed perovskite films on optoelectronic devices,such as perovskite solar cells,perovskite light-emitting diodes,and perovskite photodetectors.Finally,we highlight the“Trilogy Strategies,”including ink engineering,printing process,and posttreatment for printing high-quality perovskite films.

Remote,selective,and in situ manipulation of liquid droplets on a femtosecond laser-structured superhydrophobic shape-memory polymer by near-infrared light

Droplet manipulation plays a significant role in the fields of biomedical detection,microfluidics,and chemical engineering.However,it still remains a great challenge to simultaneously achieve remote,selective,and in situ droplet manipulation on the same surface.Here,Fe_(3)O_(4)nanoparticles were doped in a shape-memory polymer(SMP)to prepare a photothermal-responsive Fe_(3)O_(4)-SMP composite which showed remarkable near-infrared(NIR)light-triggered shape-memory property.Superhydrophobic micropillar array was constructed on such Fe_(3)O_(4)-SMP composite through femtosecond laser microfabrication and fluoroalkylsilane modification.The surface wettability of the as-prepared surface can transform from a low-adhesive sliding state to a high-adhesive pinning state as the micropillars are deformed by pressing.Interestingly,the deformed micropillars can stand up and restore to their original morphology under remote NIR light irradiation,resulting in the reversible and repeatable recovery of the ultralow-adhesive superhydrophobicity.With such light-triggered wettability switching,the droplets pinning on the sample surface can be remotely,selectively,and in situ released.Furthermore,the superhydrophobic Fe_(3)O_(4)-SMP surface is successfully applied in lossless liquid transfer,selective droplet release,and droplet-based microreactor.The as-fabricated superhydrophobic surfaces with NIR light-controlled reversible wettability will hold great promise in the fields of liquid manipulation,lab-on-a-chip,and microfluidics.

Recent progress in bio-inspired macrostructure array materials with special wettability—from surface engineering to functional applications

Bio-inspired macrostructure array(MAA,size:submillimeter to millimeter scale)materials with special wettability(MAAMs-SW)have attracted significant research attention due to their outstanding performance in many applications,including oil repellency,liquid/droplet manipulation,anti-icing,heat transfer,water collection,and oil–water separation.In this review,we focus on recent developments in the theory,design,fabrication,and application of bio-inspired MAAMs-SW.We first review the history of the basic theory of special wettability and discuss representative structures and corresponding functions of some biological surfaces,thus setting the stage for the design and fabrication of bio-inspired MAAMs-SW.We then summarize the fabrication methods of special wetting MAAs in terms of three categories:additive manufacturing,subtractive manufacturing,and formative manufacturing,as well as their diverse functional applications,providing insights into the development of these MAAMs-SW.Finally,the challenges and directions of future research on bio-inspired MAAMs-SW are briefy addressed.Worldwide efforts,progress,and breakthroughs from surface engineering to functional applications elaborated herein will promote the practical application of bio-inspired MAAMs-SW.

Recent developments of droplets-based microfluidics for bacterial analysis

Droplet-based microfluidics enables the generation of uniform microdroplets at picoliter or nanoliter scale with high frequency(∼kHz)under precise control.The droplets can function as bioreactors for versatile chemical/biological study and analysis.Taking advantage of the discrete compartment with a confined volume,(1)isolation and manipulation of a single cell,(2)improvement of in-droplet effective concen-trations,(3)elimination of heterogeneous population effects,(4)diminution of contamination risks can be achieved,making it a powerful tool for rapid,sensitive,and high-throughput detection and analysis of bacteria,even for rare or unculturable strains in conventional methods.This mini-review will focus on the generation and manipulation of micro-droplets and bacteria detection and analysis carried out by droplet-based microfluidics.Finally,applications with high potential of droplet-based bacteria analysis are briefly introduced.Due to the advantages of rapid,sensitive,high throughput,and compatibility with rare and unculturable bacteria in conventional methods,droplet-based microfluidics has tremendous potential of providing novel solutions for biological medicine,microbiological engineering,environmental ecology,etc.

Transpiration-inspired Capillary for Synchronous Synthesis and Patterning of Silver Nanoparticles

Traditional synthesis strategy of nanomaterials with complicated process and high cost limits their applications.Here,we propose a facile process for the synchronous synthesis and patterning of silver nanoparticles(Ag NPs)through the self-driven microchannel reactor with the capillary effect inspired by transpiration.The evaporation contributes to capillary and accumulation effects in the microchannels.The silver reactant-containing droplets can be spontaneously divided and distributed in multiple microchannels during the whole fabrication process by the capillary effect.The newly formed Ag NPs at the gas-liquid interface can be assembled on both sides of the microchannels by the accumulation effect.The capillary effect decreases the disturbances,which ensures the uniformity of the patterning.By the combination of microchannels with different widths,various Ag NPs-assembled patterns with stable electrical properties are achieved.This efficient strategy with a simple fabrication procedure is towards the technological engineering of nanoscale architected materials.