In this paper, we demonstrate for the first time the use of silver nanoparticles (AgNPs) for colorimetric ascorbic acid (AA) quantification in a paper-based sensor. This device is constituted by spot tests modified with AgNPs and silver ions bordered by a hydrophobic barrier which provides quantitative and fast analysis of AA. In addition, this device is employed as point-of-care monitoring using a unique drop of the sample. AgNPs paper-based sensor changed from light yellow to gray color after the addition of AA due to nanoparticle growth and clusters formation. The color intensities were altered as a function of AA concentration which were measured by either a scanner or a homemade portable transmittance colorimeter. Under the selected measurement conditions, results presented limit of detection which was comparable to analytical laboratory-based methodologies. In addition, the sensitivity of our sensor was comparable to the standard titration method when real samples were investigated.
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http://dx.doi.org/10.1016/j.talanta.2015.03.067 | DOI Listing |
Anal Chim Acta
February 2025
Department of Hygiene, Third Faculty of Medicine, Charles University, Ruská 87, 100 00, Prague 10, Czech Republic. Electronic address:
The review focuses on the design of detection cells, the use of microcontrollers for processing and evaluation of the detection signal, and the development of multi-detection systems for electromigration, liquid chromatography, flow-through and microfluidic techniques. A separate section is the introduction of modern 3D printing techniques and the use of new printing materials for the design of multidetection systems. In addition to traditional utilisation in separation techniques, new versions of contactless conductivity detectors are finding applications in FIA, SIA, portable and paper based analytical systems or as independent sensors.
View Article and Find Full Text PDFTalanta
January 2025
State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou University, Lanzhou, Gansu, 730000, People's Republic of China. Electronic address:
Mercury (II) ions (Hg) are a significant source of heavy metal contamination in groundwater, posing a serious threat to human health and the environment. Therefore, there is an urgent need for the development of a new detection technique with high sensitivity for monitoring Hg in contaminated groundwater. Here, we developed a signal amplifying MOF-based probe (NXS@ZIF-8) for on-site and ultrasensitive dual-channel portable detection of Hg in groundwater.
View Article and Find Full Text PDFPolymers (Basel)
January 2025
Department of Electronic Engineering, Faculty of Applied Energy System, Jeju National University (JNU), Jeju City 63243, Republic of Korea.
We have executed a cost-effective approach to produce a high-performance multifunctional human-machine interface (HMI) humidity sensor. The designed sensors were ecofriendly, flexible, and highly sensitive to variability in relative humidity (%RH) in the surroundings. In this study, we have introduced a humidity sensor by using carbon paper (as both a substrate and sensing material) and a silver (Ag) conductive ink pen.
View Article and Find Full Text PDFAnalyst
January 2025
The key Laboratory for Green Organic Synthesis and Application of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan, 411105, China.
Developing low-cost self-service portable sensors to detect viruses is an important step in combating the spread of viral outbreaks. Here, we describe the development of an aptamer-free paper-based molecularly imprinted sensor for the instrument-free detection of influenza virus A (H5N1). In this sensor, Whatman paper loaded with FeO nanoparticles (WP@FeO) was prepared as a substrate upon which silicon imprinting occurred in the presence of the template virus H5N1.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Department of Computer Science and Engineering, Indian Institute of Technology Indore, Indore 453552, India.
The widespread reliance on paper-based currency poses significant drawbacks, such as counterfeiting, lack of transparency, and environmental impacts. While Central Bank Digital Currencies (CBDCs) address many of these issues, their dependence on continuous internet connectivity limits their usability in scenarios with poor or no network access. To overcome such limitations, this paper introduces ElasticPay, a novel Peer-to-Peer (P2P) Offline Digital Payment System that leverages advanced hardware security measures realised through Trusted Platform Modules (TPMs), Trusted Execution Environments (TEEs), and Secure Elements (SEs).
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