A method was used to fabricate a fully inkjet-printed gas sensor matrix on photographic paper. An electrode matrix comprising 36 interdigital electrodes in a high-density layout that is easy to integrate has been fabricated using a combination of insulating ink and commercial silver ink. Molecular-imprinted polymer (MIP) inks were then made using a simple solution mixing method, and these inks were printed together with carbon black ink on the electrode matrix to complete production of the sensor. Finally, experimental dynamic sensing of volatile organic compounds verifies that for detection of gases corresponding to the MIP template molecules, the MIP layer offers improvements in both sensitivity and selectivity when compared with non-imprinted polymer layers. The matrix can produce a response of more than 20% to 3 ppm propenoic acid gas through adjustment of the printing times for the carbon black layer and the MIP layer.

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Keywords: glycogen, moisture content, Japanese wagyu beef, FT-NIR, PLSR (MSC) yielded optimum results with R p 2 of 0.795, RMSEP of 2.669%, and RPD of 2.008. The results of this study demonstrated that NIR spectroscopy offers great potential for the prediction of glycogen and moisture contents in Japanese wagyu beef samples. effect on Japanese consumers' preference owing to the improvement in beef quality such as tenderness. (2)(3)(4)(5)(6)(7) This is consistent with the conclusion that tenderness is the most important factor affecting beef palatability. (8)(9)(10)(11) However, additional studies have shown that when tenderness is at an acceptable level, flavor becomes the next most important factor affecting the beef preference of consumers. (10)(11)(12)(13)(14)(15) Flavor is a complex concept, which is composed of taste, odor, and the interaction of these factors. In our previous work, a sensory panel test was used to determine the relationship between sensory attributes (e.g., sweetness, fattiness, aroma, tenderness, flavor, and overall evaluation) and chemical composition characteristics (e.g., moisture, protein, free amino acid, glycogen, and fatty acid contents) of Japanese wagyu beef by the simmering method. (16) We demonstrated that the 'flavor' of sensory attributes was associated with glycogen and moisture contents. It has been widely reported that pre rigor muscle glycogen content has a negative curvilinear relationship with ultimate pH, (17) which is an indicator of the final palatability of meat. (18,19) In addition, the glycogen content in the muscle is related to the amounts of monosaccharides such as glucose and fructose after slaughter, which affect the development of meat flavor via the Maillard reaction; therefore, glycogen contributes to beef palatability. (20) Moisture content is often used to assess meat quality. (21) It also has a strong relationship with the contents of lipids that affect sensory attributes such as flavor, juiciness, texture, and appearance. (22) Therefore, to satisfy an increasing demand for evaluating meat quality by either the meat processing industry or consumers, fast, accurate, and nondestructive methods are urgently required.In recent years, near-infrared (NIR) spectroscopy, which is based on optical measurements of reflectance, transmittance, and interactance, has been considered as a nondestructive, fast, convenient, inexpensive, and precise technique. NIR spectroscopy combined with various multivariable data processing techniques has been effectively employed. Applications of the NIR technique to the evaluation of meat quality have been reviewed. (23) The NIR technique has the potential of detecting meat adulteration, (24,25) assessing meat microbial spoilage, (26,27) and estimating meat quality. (28,29) Nowadays, several research studies on Japanese wagyu beef have shown that NIR spectroscopy can be applied to predict the fat content and quantify the fatty acid composition. Kobayashi et al. have demonstrated the correlation between fat content and spectral infor...

The fabrication of chemiresistive sensors by inkjet printing is recognized as a breakthrough in gas-sensing applications. One challenge of this technology, however, is how to enhance the cross-selectivity of the sensor array. Herein, we present a ketjen black (KB) ink and molecularly imprinted sol−gel (MISG) inks to support the fabrication of a fully inkjet-printed chemiresistive sensor array, enabling the highly accurate recognition of volatile organic acids (VOAs) on the molecular level. The MISG/KB sensor array was prepared on a glossy photographic paper with a three-layer structure: a circuit layer by a commercial silver ink, a conductive layer by a KB ink, and an active selective layer by MISG inks imprinted by different templates. Hexanoic acid (HA), heptanoic acid, and octanoic acid were used as templates to prepare the MISGs and as targets to evaluate the detection and discrimination performance of the sensor array. Three resultant MISG/KB sensors exhibited high sensitivity and selectivity to VOA vapors. The limit of detection and imprinting factor were 0.018 ppm and 7.82, respectively, for HA-MISG/KB sensors to the corresponding target. With linear discriminant analysis of the gas responses, the MISG/KB sensor array can realize high discrimination to VOAs in single and binary mixtures. Furthermore, the proposed sensor array showed strong sensor robustness with excellent consistency, durability, bending, and humidity resistance. This work developed a fully inkjet-printed chemiresistive sensor array, enabling the realization of high cross-selectivity detection, achieving low-cost, scalable, and highly reproducible sensor fabrication, moving it closer to reliable, commercial, and wearable multi-analyte human body odor analysis potential.

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Herein, we report a novel full printing process for fabricating chemiresistor gas sensor matrixes on photographic paper with an inkjet printer. Sensor matrices, which can increase a number of sensors significantly compared to a serial sensor array, were printed on one piece of A4 photographic paper. Each sensor matrix contains 36 interdigital electrodes in an area of less than 11 mm2, which greatly improves the density of the sensor. The basic architecture of the sensor matrix is electrodes that row and column intersecting. In order to insulate the row and column electrodes from meeting each other, an insulating layer needs to be fabricated at the point of intersection between the row and column electrodes. The insulation layer was produced by adjusting the number of printing passes and shape of the printing pattern of color pigment ink. Carbon black (CB) was used to form a chemosensitive composite by changing its resistivity with a specific polymer for the preparation of sensing material. In order to make the sensing material can be printed, it is necessary to disperse CB first. CB was dispersed in aqueous solution with sodium dodecyl sulfate added as a surfactant to lower the surface tension, which enabled printing of CB using an inkjet printer. Some polymers have certain adsorption characteristics for gases. According to the different gas properties, the adsorption characteristics are also different. By adding polyethylene glycol polymer to the CB layer, the response to four gases with different properties is improved. Compared with the drop coating, the full-printing sensors not only reduces the production time significantly, but also improves the gas response magnitude to ethanol by about three times. The results demonstrate that the developed sensor can be used as a low cost, disposable, and easily printable chemical sensor.