We report the synthesis of multivariate MOFs with combinations of metal ions, including Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+. The permanent porosity and the evenly distributed metal components make...
Wearable sweat sensors have been developed rapidly in recent years due to the great potential in health monitoring. Developing a convenient manufacturing process and a novel structure to realize timeliness and continuous monitoring of sweat is crucial for the practical application of sweat sensors. Herein, inspired by the striped grooves and granular structures of bamboo leaves, we realized an epidermal patch with biomimetic multilevel structural microfluidic channels for timeliness monitoring of sweat via 3D printing and femtosecond laser processing. The striped grooves and ridges are alternately arranged at the bottom of the microfluidic channels, and the surface of the ridges has rough granular structures. The striped grooves improve the capillary effect in the microchannels by dividing the microchannels, and the granular structures enhance the slip effect of sweat by increasing surface hydrophobicity. The experimental results show that compared with the conventional microfluidic channels, the water collecting rate of the biomimetic microchannels increased by about 60%, which is consistent with the theoretical analysis. The superior sweat-collecting efficiency in the epidermal patch with the biomimetic multistructure enables sensitive, continuous, and stable monitoring of sweat physiological signals. Besides, this work provides new design and manufacturing approaches for other microfluidic applications.
Laser is a powerful tool for the synthesis of nanomaterials. The intensive laser pulses delivered to materials within nanoseconds allow the formation of novel structures that are inaccessible for conventional methods. Layered double hydroxide (LDH) nanostructures with high porosity, suitable dopants, and rich defects are desirable for catalysts, however, tremendously difficult in a one‐pot synthesis. Here it is found that confined laser shock in solvent leads to the formation of nanoreactors which guide the assembly of multiscale LDH building units, larger nanosheets as frame and smaller nanodomains as building blocks. These nanodomains have rich vacancy defects and are interlocked in a high packed density of 1013 cm−2, leaving rich mesopores across the nanosheets and coral‐like morphology. Like the natural coral reef that has multiscale structure to accommodate different marine organisms, the coral‐like LDH metastructure provides large surface area and rich active sites for the interaction with guest molecules. Benefiting from the multiscale porous structure and rational dopant, this LDH catalyst exhibits a low overpotential of 220 mV at 10 mA cm−2 for oxygen evolution reaction (OER), standing as one of the best LDH catalysts to date.
The orientation of crystals on the substrate and the presence of defects are critical factors in electro‐optic performance. However, technical approaches to guide the orientational crystallization of electro‐optical thin films remains challenging. This article reports on a novel physical method called magnetic field assisted pulse laser annealing (MAPLA) for controlling the orientation of perovskite crystals on substrates. By inducing laser recrystallization of perovskite crystals under a magnetic field and with magnetic nanoparticles, the optical and magnetic fields w ere found to guide the orientational gathering of perovskite units into nanoclusters, resulting in perovskite crystals with preferred lattice orientation in (110) and (220) perpendicular to the substrate. The perovskite crystals obtained by MAPLA exhibited significantly larger grain size and fewer defects compared to those from pulsed laser annealing (PLA) and traditional thermal annealing, resulting in improved carrier lifetime and mobility. Furthermore, MAPLA demonstrated improved device performance, increasing responsivity and detectivity by two times, and photocurrent by nearly three orders compared with PLA. The introduction of Fe2O3 nanoparticles during MAPLA not only improved crystal size and orientation but also significantly enhanced long‐term stability by preventing Pb2+ reduction. The MAPLA method has great potential for fabricating many electro‐optical thin films with desired device properties and stability.This article is protected by copyright. All rights reserved
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