Mingming Zhao,Huizi Lu,Zhiheng You,Huayun Chen,Xiao Wang,Yaqing Zhang,Yixian Wang
Developing a colorimetry-based artificial scent screening system (i.e., an olfactory visual sensing system) with high sensitivity and accurate pattern recognition for detecting fruit ripeness remains challenging. In this work, we construct a flexible dye/CelluMOFs-based sensor array with improved sensitivity for on-site detection of characteristic gases of fruits and integrate a densely connected convolutional network (DenseNet) into the sensor array, enabling it to recognize unique scent fingerprints and categorize the ripeness of fruits. In the system, CelluMOFs are synthesized through in situ growth of γ-cyclodextrin metal–organic frameworks (γ-CD-MOFs) on flexible fiber filter paper to fabricate a uniform, flexible and porous dye/CelluMOFs sensitive membrane. Compared to the pristine filter paper, the CelluMOFs exhibit increased porosity with a 62 times higher specific surface area and a 3-fold increase in dye loading capacity after 12 h of adsorption. The prepared dye/CelluMOFs sensing film shows outstanding mechanical and detection stability with negligible deviation after 100 cycles of rubbing. The colorimetric visualization arrays with multiple colorimetric dye/CelluMOFs chips, enable the sensitive recognition and detection of nine kinds of characteristic fruit odors and achieve a high response at 8–1500 ppm of trans-2-hexenal, showcasing remarkably low gas detection thresholds. On the basis of the ppm-level limit of detection with high sensitivity, the fabricated colorimetric sensor arrays are typically used for in situ assessment of fruit ripeness by integrating DenseNet. This approach achieves a satisfactory classification accuracy of 99.09% on the validation set, enabling high-precision prediction of fruit ripeness levels.
Bo Zhang,Hongwen Chen,Qiuhui Hu,Liming Jiang,Youqing Shen,Dan Zhao,Zhuxian Zhou
Natural cellulose fiber-based materials have been widely used in daily life for a broad application owing to their intrinsic merits such as easy availability, eco-friendly, good processability, and outstanding physical–mechanical properties. Surface modification of natural fibers with nanostructures is an effective strategy to integrate the textile substrates with many favorable functionalities. Here, a green, facile, and universal method is introduced for the in situ growth of γ-cyclodextrin (γ-CD) metal-organic frameworks (MOFs) in cellulose fiber-based materials (CelluMOFs). Compared to the pristine fibers, the resulting CelluMOFs have high porosity with up to 50 times larger specific surface area and enhanced loading capacity to functional molecules (essential oils, antibacterial agents, and active drugs) with 23–36 times higher loading content. The CelluMOFs also exhibit high adsorption capability to volatile organic compounds and carbon dioxide. Moreover, the CelluMOFs textiles loaded with a model drug (doxorubicin) show a steady release profile and deep skin permeation capability. These CelluMOFs combine the advantages of both cellulose fibers and CD-MOFs, which greatly extend their applications in the fragrance industry, antimicrobial, pollutant removal, and biomedical textiles.
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