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Chiral CuS NPs were prepared through a ligand-exchange process and CPL-controlled photothermal performance was realized.

Hexagonal CuS nanosheets and microspheres composed of numerous flakes were successfully prepared by sonochemical and solvothermal methods, respectively. Ultrasonic radiation and templates of Cu(OH)2 nanoribbons play important roles in the growth of CuS nanosheets. The surfactant PVP restricts the diffusion and growth process, inducing the formation of CuS microspheres under solvothermal conditions. Their better crystallinity, larger interlayer distance and incompact structure made the CuS nanosheets more conducive to the transport of sodium ions. Electrochemical studies showed that the nanosheet electrode exhibits better sodium storage performance compared to the CuS microspheres. The higher specific surface area (25.209 m2 g−1) of the CuS nanosheets provides a larger electrode/electrolyte contact area in the sodiation–desodiation process. The first discharge capacity of the CuS nanosheets could reach 398.6 mA h g−1 which is 71.18% of the theoretical capacity (560 mA h g−1). These results indicate that incompact structures have an advantage in storing sodium ions compared with compact structures.

Correction for ‘Efficient and stable electrorheological fluids based on chestnut-like cobalt hydroxide coupled with surface-functionalized carbon dots’ by Yudai Liang et al., Soft Matter, 2022, DOI: 10.1039/D2SM00176D.

Giant electrorheological (GER) fluids exhibit a high yield stress due to saturation surface polarization from contact between neighboring particles. To fine-tune the competitive performance of GER fluids, we modified the surface of the GER particles by adding silicone polyether, which strongly adsorbed at the solid-liquid interface and significantly influenced the dispersion, GER effect and electrical current density of the GER fluid. We discovered that a small amount of silicone polyether could improve the dispersion and reduce the electrical current density of the fluid. However, the steric hindrance effect suppressed the GER performance. Ultimately, an optimal solution was obtained by making tradeoffs among the dispersion, current density, viscosity, anti-sedimentation and ER effect. These tradeoffs were effective because they provided repetitive stability and wide opportunities for industrial usage.

Patterning biomolecules and cells on substrates is usually a prerequisite for biological analysis and cell studies. A stencil is a versatile tool for sample patterning owing to its reusability and easy operation but it lacks addressable fluid control and programmable change of pattern. Here, we combined the advantages of a microfluidic chip and stencil to design a digitally controlled microfluidic programmable stencil. The key design is automatic passive matrix addressing based on combined application of two types of elastomeric valves. These two valves have distinct actuation thresholds, typically 13.4 psi for a round valve and much higher than 13.4 psi for a rectangle valve. Different types of protein and cell pattern on a 2D substrate could be obtained by controlling the fluid addressing code based on the passive matrix addressing method. An automatic microsampler was also applied to facilitate fast sample selection and introduction in the patterning process. A successful protein and cell pattern was obtained which could be used for downstream analysis and study.

Graphene or reduced graphene oxide (rGO) membrane-based materials are promising for many advanced applications due to their exceptional properties. One of the most widely used synthesis methods for rGO membranes is vacuum filtration of graphene oxide (GO) on a filter membrane, followed by reduction, which shows great advantages such as operational convenience and good controllability. Despite vacuum-filtrated rGO membranes being widely used in many applications, a fundamental question is overlooked: are the top and bottom surfaces of the membranes formed at the interfaces with air and with the filter membrane respectively symmetric or asymmetric? This work, for the first time, reports the asymmetry of the vacuum-filtrated rGO membranes and discloses the filter membranes' physical imprint on the bottom surface of the rGO membrane, which takes place when the filter membrane surface pores have similar dimension to GO sheets. This result points out that the asymmetric surface properties should be cautiously taken into consideration while designing the surface-related applications for GO and rGO membranes.

Flexible films of polytungstate (PT) as active ingredients were fabricated in PDMS as a “band-Aid” to achieve controllable H2O2 release. In these different systems of an amorphous PT building block, the lengthened lifetime (bleaching process) of photo-electron–hole separation is attributed to the electron trapping of the PT network and the existence of hole scavengers. The hole scavengers further prevent recombination of electrons and holes, so that the long-lived photoelectron could provide sustainable reactive oxygen species (ROS) by trapped electrons. Transient absorption illustrates the kinetic competition between the process of photohole induced bleaching and coloration induced by weak irradiation, which suggests that the hole scavenger is vital for ROS generation. The signals of electron spin resonance further confirm the existence of ROS. The profiles of controllable H2O2 with various release efficiency were obtained via fluorescence studies. The results indicate that the H2O2 release efficiency is related to both the hole scavenger and the tungstate cluster. The released H2O2 on the responses of tumor cells were evaluated. Compared with a cancer drug, the controllable and reversible released H2O2 delivery is highly efficient in preventing the proliferation and inducing apoptosis of A375 melanoma cells.

Fog water collection represents a meaningful effort in places where regular water sources, including surface water and ground water, are scarce. Inspired by the amazing fog water collection capability of the Stenocara beetles in the Namib Desert and based on the recent work in biomimetic water collection, this work reports a facile, easy-to-operate, and low-cost method for the fabrication of a hydrophilic–superhydrophobic patterned hybrid surface towards highly efficient fog water collection. The essence of the method is incorporating a (super)hydrophobically modified metal-based gauze onto the surface of a hydrophilic polystyrene (PS) flat sheet by a simple lab oven-based thermal pressing procedure. The produced hybrid patterned surfaces consisted of PS patches sitting within the holes of the metal gauzes. The method allows for easy control over the pattern’s dimensions (e.g., patch size) by varying the gauze mesh size and the thermal pressing temperature, which is then translated into the easy optimization of the ultimate fog water collection efficiency. Given the low-cost and wide availability of both PS and the metal gauze, this method has great potential for scaling-up. The results showed that the hydrophilic–superhydrophobic patterned hybrid surfaces with a similar pattern size to the Stenocara beetles's back pattern produced a significantly higher fog collection efficiency than the uniformly (super)hydrophilic or (super)hydrophobic surfaces. This work contributes to the general effort in fabricating mixed wettability patterned surfaces for atmospheric water collection for direct use.

We report the generation and manipulation of electrorheological (ER) droplets that exhibit the giant ER effect. The experiments were carried out on specially designed microfluidic chips, in which the ER droplets were generated by using the microfluidic flow-focusing approach. Both the size and formation rate of these droplets can be controlled through digitally applied electrical signals. The principle of droplet manipulation is based on the electrical responsiveness of ER droplets and hence the denotation of “smart” when the electrical signals can be triggered by sensing/control devices. Due to the unique characteristics of the GER effect, the smart droplets can deform and even stop the microfluidic channel flow under an applied electric field. The pressure difference induced by the smart droplets inside the micro-channel is controllable by varying the field strengths, droplet sizes and particle concentrations in the GER suspension. By trapping and timed release of smart droplets in different micro-branch channels, we demonstrate that the smart droplets generated upstream cannot only be stored or displayed in the desired downstream channel(s) and thereby offer the potential of micro-droplet display, but also be useful in counting, flow directing and sorting the desired number of passive droplets sandwiched between two smart droplets. Such capabilities of smart droplets will enable the programmable control of discrete processes in bio-analysis, chemical reactions, digital microfluidics, and digital droplet display.

We give a short review of droplet microfluidics with the emphasis on “smart” droplets, which are based on materials that can be actively controlled and manipulated by external stimuli such as stress, temperature, pH, and electric field or magnetic field. In particular, the focus is on the generation and manipulation of droplets that are based on the giant electrorheological fluid (GERF). We elaborate on the preparation and characteristics of the GERF, the relevant microfluidics chip format, and the generation and control of droplets using GERF as either droplets or the carrier fluid. An important application of the GERF droplets, in the realization of first universal microfluidic logic device which can execute the 16 Boolean logic operations, is detailed.

In this communication, we report a newly developed cell pattering methodology by a silicon-based stencil, which exhibited advantages such as easy handling, reusability, hydrophilic surface and mature fabrication technologies. Cell arrays obtained by this method were used to investigate cell growth under a temperature gradient, which demonstrated the possibility of studying cell behavior in a high-throughput assay.

We demonstrate a uniquely designed microfluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant electrorheological (GER) fluid, functions as the translation media among fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale microfluidic processor with more complexity for on-chip processing for biological, chemical as well as computational experiments.