Search

Perspiration is an important physiological process that maintains thermal homeostasis and water–salt balance. However, the collection and analysis of perspiration currently rely on microfluidic technology and colorimetric assays. The complexity and high cost of fabricating microfluidic channels and the insecurity of chemical reagents for color reactions should be optimized. In this work, a colorimetry electronic skin (e‐skin) for intelligent perspiration monitoring has been realized. The colorimetry e‐skin system consists of the polyurethane (PU) nanomesh and the object detection algorithm You Only Look Once version 3 (YOLOv3). Due to the 44% porosity of the PU nanomesh and capillary action, the low‐cost PU nanomesh (<1 cent) can be used as the colorimetric indicator. The volume of the PU nanomesh expands to 362.37% as a result of perspiration being absorbed and changes the optical transmittance (up to 277.78%). A finite element model based on capillary action has been proposed to explain the change in optical transmittance. Finally, a database containing 735 images has been built, and the object detection algorithm YOLOv3 is used to analyze the perspiration absorbed by the PU nanomesh. The detection results can identify the perspiration volume with a high accuracy of 97%. These results show that this work has great potential in healthcare field. [ABSTRACT FROM AUTHOR]

The size, distribution, and specific shape of ordered nanophotonic structures are crucial for their biomedical applications. Bottom‐up approaches such as self‐assembly, emulsification, and precipitation are commonly fabricated nanophotonic structures, which often lack control of nanophotonic structures morphologies and monodispersed sizes. On the contrary, top‐down nanofabrication techniques offer the advantages of high fidelity and high controllability and are employed in the fabrication of nanophotonic structures. This review focuses on top‐down nanofabrication techniques to fabricate ordered nanophotonic structures and their biomedical applications. Several top‐down approaches used in the semiconductor industry and other fields requiring micro‐ and nanopatterns are used, including electron beam lithography/ion beam lithography, photolithography, interference lithography, nanoimprint lithography, nanosphere lithography, nanotransfer lithography, and nano‐electrodeposition. Various current and emerging biomedical applications of the ordered nanophotonic structures are also covered: i) surface‐enhanced Raman scattering, ii) plasmonics, including surface plasmon resonance and localized surface plasmon resonance, and iii) fluorescence enhancement. Finally, a future perspective of nanophotonic structures fabricated by top‐down techniques in biomedical applications is also summarized. [ABSTRACT FROM AUTHOR]

Nanophotonic metasurfaces are widely utilized in various domains, such as biomedical, healthcare, and environmental monitoring, benefiting from their unique advantages of label‐free, noninvasive, and real‐time response. However, nanophotonic metasurfaces usually rely on sophisticated instruments, and expensive and time‐consuming fabrication processes, which severely restricts their practical applications. Herein, a spatially gradient metasurface is integrated with an imaging‐based sensing scheme, waiving the requirement of spectrometers and achieving an ultrahigh imaging‐based sensitivity of 3321 pixels/refractive index unit superior to that characterized using conventional compact spectrometers. The metasurface is fabricated by nanoimprint lithography using a reusable cyclic olefin copolymer template featuring millions of unique nanostructures. Under the illumination of monochromatic light, the transmittance of different nanostructures on the metasurface differs, resulting in grayscale images with varied intensity distributions. Analyzing the intensity change of the metasurface's recorded image can obtain the covering medium's refractive index. Furthermore, through theory and experimentation, the high reliability of the proposed reusable and flexible template has been verified for nanophotonic metasurface fabrication which further reduces the fabrication cost of core sensing elements. Finally, with proper optimization of the metasurface structure and imaging system, this setup is expected to be applied to many emerging areas of point‐of‐care, real‐time, and on‐site biosensing. [ABSTRACT FROM AUTHOR]

Classifying and quantifying small molecules on‐site with a rapid and cost‐effective operation are essential for pharmaceutical manufacturing, healthcare, hazardous risk control, and other applications. However, traditional molecular detection and identification methods like chromatography often involve expensive and bulky equipment and are required to be operated by trained professionals, which severely hinders the further development of small molecule‐based applications. Herein, a novel molecular detection platform is introduced by imaging a spatial gradient metasurface consisting of millions of different unique atoms and following with deep learning modeling to classify and quantify small molecules from mixed solutions accurately. The metasurface has a circular gradient geometry, which changes its transmittance intensity pattern based on the surrounding molecules under narrow‐band illumination. A convolutional neural network trained on the monochromatic images of the metasurface is employed. The results demonstrate a recognition rate of 96.88% for classification and a mean absolute error of 16.23% for quantification. This novel platform enables label‐free, sensitive, and rapid molecular classification and quantification, which opens a new avenue for small molecule classification and quantification and enables possibilities for real‐time, on‐site, and label‐free applications, including environmental monitoring, drug screening, and early diagnosis. [ABSTRACT FROM AUTHOR]

The spontaneous evolution of vernacular architecture mainly relies on the inheritance of architectural traditions and the innovative decisions of occupants, rather than the professional guidance of architects and the promotion of government agencies. This study introduces a new and rapidly developing phenomenon of spontaneous green evolution of vernacular architecture into the professional field, and conducts scientific research on its technical characteristics, system effects, and optimization methods. Based on the phenomenon of roofing of courtyards (CBR) in southern Hebei, we intervene from the professional point of view of architects, make the best use of the situation, and moderately intervene in its scientific development. By re-examining the adaptability of the open and closed attributes of courtyard buildings to specific climatic conditions and living patterns, the performance improvement and potential risks brought by CBR to local vernacular buildings are systematically analyzed, and the improvement strategies and promotion paths of CBR are explored. The research aims to form a relay and interaction between the professional intervention of architects and the spontaneous evolution of folk wisdom, and to explore the sustainable development of vernacular architecture. The findings help to improve the health and comfort of existing vernacular buildings, as well as to contribute to the improvement of rural human settlements. [ABSTRACT FROM AUTHOR]

Abstract: The dielectric, ferroelectric and fatigue properties of modified lead zirconate titanate (PZT) ceramics were investigated in terms of the effect of La0.8Sr0.2MnO3 (LSM) buffer layers. The double sided LSM buffer layers resulted in a lower dielectric loss, a weaker frequency dependence of dielectric constant, a lower leakage current density, and an increase in the saturation polarization. Moreover, it was found that up to 1.4×107 cycle numbers, the Ag||LSM/PZT/LSM||Ag capacitor, with remanent polarization decreased by 55%, was superior to the Ag||PZT||Ag capacitor by 85%. The results indicate that the LSM buffer layers can improve the fatigue endurance of the PZT ceramics with Ag electrodes, mainly because the accumulated charges were compensated at the interface junctions between the LSM buffer layers and the Ag electrodes. We fit the polarization fatigue data using a modified model and calculated the characteristic decay time of oxygen vacancy migration in the Ag||LSM/PZT/LSM||Ag and the Ag||PZT||Ag capacitors, respectively. [Copyright &y& Elsevier]