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Suitable micropumping methods for flow control represent a major technical hurdle in the development of microfluidic systems for point-of-care testing (POCT). Passive micropumping for point-of-care microfluidic systems provides a promising solution to such challenges, in particular, passive micropumping based on capillary force and air transfer based on the air solubility and air permeability of specific materials. There have been numerous developments and applications of micropumping techniques that are relevant to the use in POCT. Compared with active pumping methods such as syringe pumps or pressure pumps, where the flow rate can be well-tuned independent of the design of the microfluidic devices or the property of the liquids, most passive micropumping methods still suffer flow-control problems. For example, the flow rate may be set once the device has been made, and the properties of liquids may affect the flow rate. However, the advantages of passive micropumping, which include simplicity, ease of use, and low cost, make it the best choice for POCT. Here, we present a systematic review of different types of passive micropumping that are suitable for POCT, alongside existing applications based on passive micropumping. Future trends in passive micropumping are also discussed.

Electrochemical CO2 reduction reaction (CO2RR) offers a sustainable strategy for producing fuels and chemicals. However, it suffers from sluggish CO2 activation and slow water dissociation. In this work, we construct a (P−O)δ− modified In catalyst that exhibits high activity and selectivity in electrochemical CO2 reduction to formate. A combination of in situ characterizations and kinetic analyses indicate that (P−O)δ− has a strong interaction with K+(H2O)n, which effectively accelerates water dissociation to provide protons. In situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) measurements together with density functional theory (DFT) calculations disclose that (P−O)δ− modification leads to a higher valence state of In active site, thus promoting CO2 activation and HCOO* formation, while inhibiting competitive hydrogen evolution reaction (HER). As a result, the (P−O)δ− modified oxide‐derived In catalyst exhibits excellent formate selectivity across a broad potential window with a formate Faradaic efficiency as high as 92.1 % at a partial current density of ~200 mA cm−2 and a cathodic potential of −1.2 V vs. RHE in an alkaline electrolyte. [ABSTRACT FROM AUTHOR]

Exploring the gas-solid compatibility between insulating gas and solids materials used in electrical equipment is of great significance for determining the long-term behavior of insulating gas trifluoromethanesulonyl fluoride (CF3SO2F). The gas-solid compatibility of CF3SO2F and its decomposition products with Ag, Zn, and ZnO common surfaces has been assessed based on first-principles calculations, with SF6 as the control group. CF3SO2F has excellent gas-solid compatibility with the solid surfaces by analyzing the adsorption configurations, adsorption energies, charge transfer, adsorption height, density of states, and ab initio molecular dynamics (AIMD) results. The external electric fields do not affect the excellent compatibility between CF3SO2F and the solid surfaces. Besides, the Ag(111) surface exhibits fine gas-solid compatibility with all decomposition products benefitting from its low surface energy. Originating in the existence of the three-center-four-electron (3c4e) π bond and F atoms with strong electronegativity in SO2F2, SO2F2 has poor compatibility with the Ag(110), (100), and Zn(001) surface. SO2, COF2, and HF gases may accelerate equipment failure due to the strong adsorption strength and poor compatibility with ZnO(100) and (110) surfaces. The results provide the theoretical guidance for the engineering application and long-term performance evaluation of CF3SO2F. [ABSTRACT FROM AUTHOR]

Silver and gold nanoparticles have found extensive biomedical applications due to their strong localized surface plasmon resonance (LSPR) and intriguing plasmonic properties. This review article focuses on the correlation among particle geometry, plasmon properties and biomedical applications. It discusses how particle shape and size are tailored via controllable synthetic approaches, and how plasmonic properties are tuned by particle shape and size, which are embodied by nanospheres, nanorods, nanocubes, nanocages, nanostars and core–shell composites. This article summarizes the design strategies for the use of silver and gold nanoparticles in plasmon-enhanced fluorescence, surface-enhanced Raman scattering (SERS), electroluminescence, and photoelectrochemistry. It especially discusses how to use plasmonic nanoparticles to construct optical probes including colorimetric, SERS and plasmonic fluorescence probes (labels/reporters). It also demonstrates the employment of Ag and Au nanoparticles in polymer- and paper-based microfluidic devices for point-of-care testing (POCT). In addition, this article highlights how to utilize plasmonic nanoparticles for in vitro and in vivo bio-imaging based on SERS, fluorescence, photoacoustic and dark-field models. Finally, this article shows perspectives in plasmon-enhanced photothermal and photodynamic therapy. [ABSTRACT FROM AUTHOR]

The adaptability of living organisms to dynamically adjust their biological behavior in response to fluctuating surroundings is a prerequisite for their evolutionary success. However, artificially‐synthesized materials, especially semiconductors, have not been able to replicate such adaptability due to their inherent physical rigidity and lack of intrinsic structural responsiveness to external stimuli. Herein, an adaptive structural evolution in group‐III‐nitride semiconductors is demonstrated by constructing an AlGaN‐nanowire/Ni(OH)2 symbiotic‐system, resulting in self‐improved optoelectronic characteristics. The mutualistic interplay between AlGaN and Ni(OH)2 nanostructure leads to the adaptive evolution of crystalline‐facets of AlGaN‐nanowires, along with self‐optimization of Ni(OH)2 nanocrystals upon photon‐irradiation during its operation. Specifically, the nanowire‐surfaces dynamically evolve during Ni(OH)2 photo‐deposition, removing the (0001¯$\bar{1}$) plane while exposing the (101¯1¯$\bar{1}\bar{1}$), which facilitates carrier transport at AlGaN/Ni(OH)2 interface. Moreover, light‐induced electrons generated from AlGaN‐nanowires then partially reduce Ni2+ ions in the Ni(OH)2 nanostructure into Ni0 nanometals, which further boosts the proton reduction thermodynamics, generating an unusual self‐improving photocurrent from −59.6 to −101.6 µA cm−2. Such a "symbiotic system," which is barely observed in conventional semiconductors, provides a promising avenue toward realizing smart adaptive semiconductors that are capable of dynamic structural evolution to fully unleash their potential for emerging optoelectronic and artificial‐photocatalysis applications. [ABSTRACT FROM AUTHOR]

In this study, 3D representative volume element models with microchannels were established based on measured data. And the periodic boundary conditions were moderately modified to adapt to the actual constraints of the studied object. The effects of different microvascular parameters on the tensile and compressive properties of composites were studied. And the damage pattern of carbon fiber as the main load-bearing phase under the force was analyzed. The models were verified by tensile testing and micromorphology experiments. The research results are of application to the design and analysis of CFRP laminates containing similar microchannel structures. [ABSTRACT FROM AUTHOR]

Plasmonic patterns with gaps of less than 10 nm have wide applications for various optoelectronic devices, for example, the surface‐enhanced Raman spectroscopy (SERS) detection of toxic pesticide contaminants that pose a serious threat to human health. Here, a cost‐effective and highly controllable approach for such ultrafine patterns by combining the characteristic strengths of two techniques, the tunable and ordered porous structure of the anodic aluminum oxide template technique and the conformal atomic layer‐by‐layer growth feature of the atomic layer deposition technique, is reported. This novel nanofabrication approach can tailor the geometry and dimension of the inner‐pillar/outer‐ring or inner‐ring/outer‐ring nano‐arrays at the nanometer scale with high reproducibility. As a result, multiple large‐area (cm2 scale) ordered and high‐density coaxial circular nano‐slit arrays with adjustable slit width down to 2 nm are produced. Such narrow metallic nano‐slits can generate strong "hot spots" where huge signal enhancement happens, leading to a SERS enhancement factor of up to 4 × 108. This enables the detection of rhodamine 6G at an ultra‐low concentration of 10 fm, as well as toxic pesticide contaminants such as chlorpyrifos and thiram in lake water, with limits of detection of 0.25 ppm and 1.8 ppb, respectively. [ABSTRACT FROM AUTHOR]

Designing prominent gas sensor materials for the detection of environmentally friendly insulating gas C4F7N decomposition products is a reliable strategy for diagnosing the operating state of insulation equipment. The gas sensing performance of the pristine and strained two-dimensional (2D) Ga2O3 towards C4F7N decomposition products has been assessed based on first-principles calculations. Analyses of changes in electronic structures and adsorption configuration indicate that 2D-Ga2O3 is an ideal gas sensor material for C3F6 by virtue of its evident selectivity, high sensitivity, excellent stability, and moderate adsorption strength. A new descriptor w is provided to explain the different gas sensitivity of Ga2O3 towards CxF2x gas with one carbon–carbon double bond. Besides, biaxial strain engineering is an eminent pathway to adjust the adsorption energy and sensitivity of 2D-Ga2O3 towards C3F6 by inducing local structural transformation of the adsorption configuration. These results not only suggest the prospects of pristine and strained 2D-Ga2O3 in gas sensor materials but also offer new insights into the selective detection of C4F7N decomposition products by 2D-Ga2O3. [ABSTRACT FROM AUTHOR]

Hydrogels with adaptable optical and mechanical characteristics show considerable promise for light delivery in vivo with neuroengineering applications. However, the unlinked amorphous polymer chains within hydrogels can cause volumetric swelling after water absorption under physiological conditions over time. Chemically cross-linked poly(vinyl alcohol) (PVA) hydrogels showcase fatigue-resistant attributes and promising biocompatibility for the manufacture of soft neural probes. However, possible swelling of the PVA hydrogel matrix could impact the structural stability of hydrogel-based bioelectronics and their long-term in vivo functionality. In this study, we utilized an atomic layer deposition (ALD) technique to generate an inorganic, silicon dioxide (SiO2) coating layer on chemically cross-linked PVA hydrogel fibers. To evaluate the stability of SiO2-coated PVA hydrogel fibers mimicking the in vivo environment, we conducted accelerated stability tests. SiO2-coated PVA hydrogel fibers showed improved stability over a one-week incubation period under a harsh environment, preventing swelling and preserving their mechanical and optical properties compared to uncoated fibers. These SiO2-coated PVA hydrogel fibers demonstrated nanoscale polymeric crystalline domains (6.5 ± 0.1 nm), an elastic modulus of 73.7 ± 31.7 MPa, a maximum elongation of 113.6 ± 24.2%, and minimal light transmission loss (1.9 ± 0.2 dB cm−1). Lastly, we applied these SiO2-coated PVA hydrogel fibers in vivo to optically activate the motor cortex of transgenic Thy1::ChR2 mice during locomotor behavioral tests. This mouse cohort was genetically modified to express the light-sensitive ion channel, channelrhodopsin-2 (ChR2), and implanted with hydrogel fibers to deliver light to the motor cortex area (M2). Light stimulation via hydrogel fibers resulted in optogenetically modulated mouse locomotor behaviors, including increased contralateral rotation, mobility speeds, and travel distances. [ABSTRACT FROM AUTHOR]

Improving the structural stability and property contrast of phase-change materials is important to make phase-change random access memories work in prolonged service stably. Based on the density functional theory and ab initio molecular dynamics simulations, we analyze the structural, electronic, and optical properties of Sb-rich amorphous Ge3Sb6Te5, in comparison with the traditional amorphous Ge2Sb2Te5. The results show that excess Sb concentration can promote the formation of wrong bonds, tetrahedrons, and fivefold rings, which are beneficial for the structural stability of amorphous phases. In addition, Ge3Sb6Te5 has a bigger difference in the bandgap and dielectric function between the crystalline and amorphous phases, indicating that excess Sb concentration can improve the electrical and optical property contrast between the two phases. Our calculation will provide a theoretical basis for applying Sb-rich Ge3Sb6Te5 to retain data stably in prolonged service. [ABSTRACT FROM AUTHOR]

The fundamental photophysics involved in the doping effect of zero-dimensional (0D) lead-free tin-halide perovskites (Cs4SnX6, X = Br and I), especially the dynamics of self-trapped excitons (STEs), is crucial for their practical applications. Here, we proposed the use of Mn2+ doping to realize efficient emission from the STEs in Cs4SnBr6. The Mn2+-doped Cs4SnBr6 exhibits an enhanced photoluminescence (PL) quantum yield of up to ∼75.8%, a broadened emission spectrum, and improved thermal stability. The experimental observations combined with first-principles calculations reveal that the significant PL enhancement originates from the enhanced electron–phonon coupling and the increased binding energies of STEs, as a consequence of the large distortion of [SnBr6]4− octahedra induced by Mn2+ doping. In addition, it was verified that the color tuning of Mn2+-doped Cs4SnBr6 is achieved by the competitive transfers of free excitons to STE states and Mn2+ sites based on time-resolved and temperature-dependent PL measurements. The Mn2+-doped Cs4SnBr6 assembled into commercial UV-LED chips exhibits strong white light emission with a color temperature of 6346 K. Our findings not only provide deep insight into the dynamics of STEs in Mn2+-doped Cs4SnBr6 but also open new horizons for manipulating and optimizing the emission of STEs in 0D perovskites, thereby laying a foundation for developing white LEDs based on 0D perovskites. [ABSTRACT FROM AUTHOR]