[en] This article is a concise overview about the developing microfluidic systems named surface-tension-confined droplet microfluidics (STORMs). Different from traditional complexed droplet microfluidics which generated and confined the droplets by three-dimensional (3D) poly(dimethylsiloxane)-based microchannels, STORM systems provide two-dimensional (2D) platforms for control of droplets. STORM devices utilize surface energy, with methods such as surface chemical modification and mechanical processing, to control the movement of fluid droplets. Various STORM devices have been readily prepared, with distinct advantages over conventional droplet microfluidics, which generated and confined the droplets by 3D poly(dimethylsiloxane)-based microchannels, such as significant reduction of energy consumption necessary for device operation, facile or even direct introduction of droplets onto patterned surface without external driving force such as a micropump, thus increased frequency or efficiency of droplets generation of specific STORM device, among others. Thus, STORM devices can be excellent alternatives for majority areas in droplet microfluidics and irreplaceable choices in certain fields by contrast. In this review, fabrication methods or strategies, manipulation methods or mechanisms, and main applications of STORM devices are introduced. (topical review — soft matter and biological physics)

[en] The transition metal dichalcogenides (TMDCs) have drawn considerable attention because their unique application in novel quantum optoelectronic devices. Here, we design the MoS₂-like Janus InSeF film and stacked two different layers to form hereostructures. The first principles study results show that F bonds to In, with the atoms in the sequence of F-In-Se-Se-In-F. The calculated band structures shows a semiconducting character with a gap of 0.58 eV. The band gap is sensitive to strains, varied from 0 to 1.23 eV. Remarkably, this film can turn from a normal insulator to topological insulator (TI) under appropriate compressive strain. Also, we find a direct-to-indirect band gap transition, if the tensile strain growing. These results mean that it provides an ideal platform to realize low-dissipation quantum and spintronic devices based on InSeF films.

[en] Highlights: • a perovskite crystal array was prepared by one-step evaporation-induced self-assembly. • Multi-wavelength photoluminescence emission arises from component segregation in crystal. • Radom macrosegregation of perovskite crystal arrays provides opportunity for PUFs. • All-photonic cryptographic primitive was generated from PUFs based on the crystal array. • Such a high-throughput programming and authentication is of high-reliability and low-cost. Segregation is a phenomenon of inhomogeneous distribution of constituent elements during crystallization and could be found in alloy, polymers, colloid, etc. Some researchers have also found component segregation in perovskite crystals. Until now, the existing research reports are all about the halogen segregation of perovskite at the micro level, while the research about the component segregation of perovskite at the macro level is blank, leaving no relevant application developed. Therefore, we can broaden the PUFs-based application of perovskite crystals by employing the multi-wavelength emission property arising from component macrosegregation. We synthesized perovskite crystal arrays with macroscopic composition segregation in one step by surface-tension-confined evaporative self-assembly. The macrosegregation in perovskite crystals prepared with different halogen ratios and temperature was surveyed. The photoluminescence spectra of perovskite crystals were investigated. Perovskite crystals with composition segregation could generate physically unclonable cryptographic primitives, which were made by a simple and random process and difficult to replicate. According to the number of peaks in the spectrum, we converted the optical response into quaternary cryptographic keys, and demonstrated the randomness and stability of the system. This study excavated the application prospect of macroscopic component segregation perovskite in all-photonic cryptographic primitives.