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10 pages, 2588 KiB  
Proceeding Paper
Combining Interactive Technology and Visual Cognition—A Case Study on Preventing Dementia in Older Adults
by Chung-Shun Feng and Chao-Ming Wang
Eng. Proc. 2025, 89(1), 16; https://doi.org/10.3390/engproc2025089016 - 25 Feb 2025
Viewed by 626
Abstract
According to the World Health Organization, the global population is aging, with cognitive and memory functions declining from the age of 40–50. Individuals aged 65 and older are particularly prone to dementia. Therefore, we developed an interactive system for visual cognitive training to [...] Read more.
According to the World Health Organization, the global population is aging, with cognitive and memory functions declining from the age of 40–50. Individuals aged 65 and older are particularly prone to dementia. Therefore, we developed an interactive system for visual cognitive training to prevent dementia and delay the onset of memory loss. The system comprises three “three-dimensional objects” with printed 2D barcodes and near-field communication (NFC) tags and operating software processing text, images, and multimedia content. Electroencephalography (EEG) data from a brainwave sensor were used to interpret brain signals. The system operates through interactive games combined with real-time feedback from EEG data to reduce the likelihood of dementia. The system provides feedback based on textual, visual, and multimedia information and offers a new form of entertainment. Thirty participants were invited to participate in a pre-test questionnaire survey. Different tasks were assigned to randomly selected participants with three-dimensional objects. Sensing technologies such as quick-response (QR) codes and near-field communication (NFC) were used to display information on smartphones. Visual content included text-image narratives and media playback. EEG was used for visual recognition and perception responses. The system was evaluated using the system usability scale (SUS). Finally, the data obtained from participants using the system were analyzed. The system improved hand-eye coordination and brain memory using interactive games. After receiving visual information, brain function was stimulated through brain stimulation and focused reading, which prevents dementia. This system could be introduced into the healthcare industry to accumulate long-term cognitive function data for the brain and personal health data to prevent the occurrence of dementia. Full article
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14 pages, 1762 KiB  
Article
NFC Tag Awareness and Its Visual Implementation on Food Packaging: Case Study in Slovenia
by Tina Žurbi and Diana Gregor-Svetec
Appl. Sci. 2024, 14(21), 9933; https://doi.org/10.3390/app14219933 - 30 Oct 2024
Cited by 1 | Viewed by 2351
Abstract
Many companies are using smart packaging to provide consumers with more information about their products. The goal of our case study is to access the Near Field Communication (NFC) tag knowledge, as well as getting insights into tag positioning in food package design [...] Read more.
Many companies are using smart packaging to provide consumers with more information about their products. The goal of our case study is to access the Near Field Communication (NFC) tag knowledge, as well as getting insights into tag positioning in food package design for better visibility in order to develop some guidelines for future tag implementations. A preliminary survey of professionals provided an overview of NFC tag usage, followed by an online survey that assessed knowledge and visibility of tag placements. These findings were further discussed in focus groups and measured using eye-tracking technology. For placement visibility assessments, well-known and fictitious packaging designs of milk were used. The results show that, due to the NFC tag’s low market penetration, consumer recognition is low, with only generations Y and Z being familiar with the NFC tag. Knowledge of the NFC tag does not significantly vary based on education level. When considering the use of NFC tags, it is crucial to define and understand the target market. If the target is younger generations, the potential to increase engagement with the product can be achieved. Additionally, to boost consumer interaction, NFC tags or other smart elements should include an activation prompt, positioned on the central right section of the packaging and distinguished by a distinct color. The influence of the design on tag visibility is essential to ensure its effectiveness. Full article
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29 pages, 14405 KiB  
Article
Data Immunity in Near Field Radio Frequency Communication Systems—NFC as an Aspect of Electromagnetic Information Security
by Andrzej Firlej, Slawomir Musial and Ireneusz Kubiak
Appl. Sci. 2024, 14(13), 5854; https://doi.org/10.3390/app14135854 - 4 Jul 2024
Cited by 1 | Viewed by 1508
Abstract
The NFC and MIFARE systems (referred to as HF-band RFID) are a special case of Radio Frequency Identification (RFID) technology using a radio frequency of 13.56 MHz for communication. The declared range of such communication is usually several cm and is characterized by [...] Read more.
The NFC and MIFARE systems (referred to as HF-band RFID) are a special case of Radio Frequency Identification (RFID) technology using a radio frequency of 13.56 MHz for communication. The declared range of such communication is usually several cm and is characterized by the need to bring the data carrier close to the system reader. Due to the possibility of transmitting sensitive data in this type of system, an important problem seems to be the electromagnetic security of the transmitted data between the cards (tags) and the reader and within the system. In most of the available research studies, the security of RFID systems comes down to the analysis of the effectiveness of encryption of transmitted data or testing the range of communication between the reader and the identifier. In this research, however, special attention is paid to the so-called electromagnetic information security without the analysis of cryptographic protection. In some cases (e.g., data retransmission), encryption may not be an effective method of securing data (because, e.g., encrypted data might be used to open and start a car with a keyless system). In addition, the research draws attention to the fact that the data from the identifier can be accessed not only from the identifier, but also from the control system (reader, wiring, controller, etc.) from which the data can be radiated (unintentionally) at a much greater distance than the communication range between the identifier and the reader. In order to determine the security of the transmitted data in the HF-band RFID systems, a number of tests were carried out with the use of specialized equipment. During the measurements, both the data carriers themselves (cards, key fobs, stickers, tags) and exemplary systems for reading data from the media (a writable card reader, a mobile phone with NFC function, and an extensive access control system) were tested. The experiments carried out made it possible to determine the safety of NFC and MIFARE systems during their use and only storage (e.g., the ability to read data from an identification card stored in a pocket). Full article
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3 pages, 924 KiB  
Abstract
Small Footprint Temperature Sensing NFC Tag
by Jorge Pereira, Inês S. Garcia, Gabriel Ribeiro, José Fernandes, Filipe S. Alves, Marco Martins, André Cardoso and Rosana A. Dias
Proceedings 2024, 97(1), 182; https://doi.org/10.3390/proceedings2024097182 - 12 Apr 2024
Viewed by 1270
Abstract
Smart NFC tags are seeing many interesting applications and can benefit from further miniaturization. A passive temperature sensing tag with 5.1 mm diameter is demonstrated, comprising a thin-film microfabricated antenna and an NFC chip. The microantenna/coil comprises two 15 µm-thick electroplated copper layers [...] Read more.
Smart NFC tags are seeing many interesting applications and can benefit from further miniaturization. A passive temperature sensing tag with 5.1 mm diameter is demonstrated, comprising a thin-film microfabricated antenna and an NFC chip. The microantenna/coil comprises two 15 µm-thick electroplated copper layers embedded in SU-8, withstanding the soldering process of a BGA NFC IC. The µ-antenna design challenge is to miniaturize while minimizing performance impairment (inductive-coupling distance), while the micromachining process is very dependent on topography propagation. Fabricated coils were successfully characterized (2.32 µH inductance; 13.76 MHz self-resonance) and temperature was read (after assembly) with a mobile phone at distances of up to 7 mm. Full article
(This article belongs to the Proceedings of XXXV EUROSENSORS Conference)
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16 pages, 6327 KiB  
Article
ZnO Decorated Graphene-Based NFC Tag for Personal NO2 Exposure Monitoring during a Workday
by Alejandro Santos-Betancourt, José Carlos Santos-Ceballos, Mohamed Ayoub Alouani, Shuja Bashir Malik, Alfonso Romero, José Luis Ramírez, Xavier Vilanova and Eduard Llobet
Sensors 2024, 24(5), 1431; https://doi.org/10.3390/s24051431 - 22 Feb 2024
Cited by 6 | Viewed by 2764
Abstract
This paper presents the integration of a sensing layer over interdigitated electrodes and an electronic circuit on the same flexible printed circuit board. This integration provides an effective technique to use this design as a wearable gas measuring system in a target application, [...] Read more.
This paper presents the integration of a sensing layer over interdigitated electrodes and an electronic circuit on the same flexible printed circuit board. This integration provides an effective technique to use this design as a wearable gas measuring system in a target application, exhibiting high performance, low power consumption, and being lightweight for on-site monitoring. The wearable system proves the concept of using an NFC tag combined with a chemoresistive gas sensor as a cumulative gas sensor, having the possibility of holding the data for a working day, and completely capturing the exposure of a person to NO2 concentrations. Three different types of sensors were tested, depositing the sensing layers on gold electrodes over Kapton substrate: bare graphene, graphene decorated with 5 wt.% zinc oxide nanoflowers, or nanopillars. The deposited layers were characterized using FESEM, EDX, XRD, and Raman spectroscopy to determine their crystalline structure, morphological and chemical compositions. The gas sensing performance of the sensors was analyzed against NO2 (dry and humid conditions) and other interfering species (dry conditions) to check their sensitivity and selectivity. The resultant-built wearable NFC tag system accumulates the data in a non-volatile memory every minute and has an average low power consumption of 24.9 µW in dynamic operation. Also, it can be easily attached to a work vest. Full article
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40 pages, 6353 KiB  
Review
Recent Advances in Batteryless NFC Sensors for Chemical Sensing and Biosensing
by Antonio Lazaro, Ramon Villarino, Marc Lazaro, Nicolau Canellas, Beatriz Prieto-Simon and David Girbau
Biosensors 2023, 13(8), 775; https://doi.org/10.3390/bios13080775 - 31 Jul 2023
Cited by 24 | Viewed by 6602
Abstract
This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have [...] Read more.
This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed. Full article
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11 pages, 7227 KiB  
Article
NFC-Enabled Dual-Channel Flexible Printed Sensor Tag
by Jonghyun Choi, Ian Visagie, Yi Chen, Robert Abbel and Kate Parker
Sensors 2023, 23(15), 6765; https://doi.org/10.3390/s23156765 - 28 Jul 2023
Cited by 6 | Viewed by 3198
Abstract
Wireless sensor tags in flexible formats have numerous applications; some are commercially available for specific target applications. However, most of these wireless sensor tags have been used for single-sensing applications. In this study, we designed a printed circuit board (PCB) module (13 mm [...] Read more.
Wireless sensor tags in flexible formats have numerous applications; some are commercially available for specific target applications. However, most of these wireless sensor tags have been used for single-sensing applications. In this study, we designed a printed circuit board (PCB) module (13 mm × 13 mm) for near-field communication-enabled sensor tags with both electrical resistance and capacitance read-out channels that enables dual-channel sensing. As part of the wireless sensor tag, a square antenna pattern was printed directly on a flexible poly(ethylene terephthalate) (PET) substrate and integrated into the PCB module to demonstrate a dual-channel temperature and ethylene gas sensor. The temperature and ethylene sensors were printed using a positive temperature coefficient ink and a tin oxide (SnO2) nanoparticle ink, respectively. With dual sensing capabilities, this type of sensor tag can be used in smart packaging for the quality monitoring of fresh produce (e.g., bananas) by tracking temperature and ethylene concentration in the storage/transport environment. Full article
(This article belongs to the Special Issue Smart Packaging Sensors for Food Quality Monitoring)
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11 pages, 1829 KiB  
Article
Intelligent Materials for Labeling Dentures in Forensic Dental Identification—A Pilot Study
by Corina Laura Ştefănescu, Lavinia Simona Neculai-Cândea, Marius Florentin Popa, Agripina Zaharia, Rodica Maria Murineanu, Ştefan Pricop, Liliana Sachelarie, Loredana Liliana Hurjui and Vlad Danila
Appl. Sci. 2023, 13(9), 5574; https://doi.org/10.3390/app13095574 - 30 Apr 2023
Viewed by 1988
Abstract
(1) Background: the present study continues previous research on new marking techniques by using intelligent materials, NFC-tags (Near Field Communication tags) and Aerogel. They prevent the loss of information over time for cadavers of unknown identities in various stages of destruction or unknown [...] Read more.
(1) Background: the present study continues previous research on new marking techniques by using intelligent materials, NFC-tags (Near Field Communication tags) and Aerogel. They prevent the loss of information over time for cadavers of unknown identities in various stages of destruction or unknown living victims, as well as missing persons who have lost or are concealing their identity. (2) Methods: this study consisted of a technological and an experimental stage. In the technological stage, two different sizes were used: round (Ø 1 cm, 0.1 mm thickness, 0.1 g weight) and square (5/5/0.1 mm), both with a 140 byte memory and high-temperature resistance (at max. 200 °C), (by the classical producing technology). After loading the identification information on the NFC-tags, they were embedded (either alone or protected by Aerogel) in the sample dentures using a new “sandwich technique” method, before the polymerization process. In the experimental stage, the sample dentures with the new materials were exposed to various damaging environments such as liquid media (sea water, fresh water, alcohol 40%, and HCl 0.2%) in order to test the time resistance of the identification elements. The samples were monitored and tested over four years. (3) Results: the information stored on the NFC tags was retrieved unaltered at the end of the monitoring period, regardless of the damage caused by the liquid media to the sample denture material and will provide an innovative solution as compared to other labeling methods. (4) Conclusion: the use of intelligent materials for labeling acrylic dentures provides additional reliability by preserving the identification information over time. Full article
(This article belongs to the Special Issue Forensic Medicine and Its Applications)
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15 pages, 3631 KiB  
Article
Near-Field Communication Tag for Colorimetric Glutathione Determination with a Paper-Based Microfluidic Device
by Inmaculada Ortiz-Gómez, Almudena Rivadeneyra, José F. Salmerón, Ignacio de Orbe-Payá, Diego P. Morales, Luis Fermín Capitán-Vallvey and Alfonso Salinas-Castillo
Biosensors 2023, 13(2), 267; https://doi.org/10.3390/bios13020267 - 13 Feb 2023
Cited by 11 | Viewed by 3121
Abstract
Here, we propose a microfluidic paper-based analytical device (µPAD) implemented with a near-field communication (NFC) tag as a portable, simple and fast colorimetric method for glutathione (GSH) determination. The proposed method was based on the fact that Ag+ could oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) [...] Read more.
Here, we propose a microfluidic paper-based analytical device (µPAD) implemented with a near-field communication (NFC) tag as a portable, simple and fast colorimetric method for glutathione (GSH) determination. The proposed method was based on the fact that Ag+ could oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into oxidized blue TMB. Thus, the presence of GSH could cause the reduction of oxidized TMB, which resulted in a blue color fading. Based on this finding, we developed a method for the colorimetric determination of GSH using a smartphone. A µPAD implemented with the NFC tag allowed the harvesting of energy from a smartphone to activate the LED that allows the capture of a photograph of the µPAD by the smartphone. The integration between electronic interfaces into the hardware of digital image capture served as a means for quantitation. Importantly, this new method shows a low detection limit of 1.0 µM. Therefore, the most important features of this non-enzymatic method are high sensitivity and a simple, fast, portable and low-cost determination of GSH in just 20 min using a colorimetric signal. Full article
(This article belongs to the Section Biosensors and Healthcare)
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25 pages, 6803 KiB  
Article
A Tiny Flexible Differential Tension Sensor
by Piotr Z. Wieczorek, Krzysztof Starecki, Krzysztof Gołofit, Maciej Radtke and Marcin Pilarz
Sensors 2023, 23(4), 1819; https://doi.org/10.3390/s23041819 - 6 Feb 2023
Cited by 1 | Viewed by 2236
Abstract
Modern applications of Internet of Things (IoT) devices require cheap and effective methods of measurement of physical quantities. Cheap IoT devices with sensor functionalities can detect a lack or excess of substances in everyday life or industry processes. One possible use of tension [...] Read more.
Modern applications of Internet of Things (IoT) devices require cheap and effective methods of measurement of physical quantities. Cheap IoT devices with sensor functionalities can detect a lack or excess of substances in everyday life or industry processes. One possible use of tension sensors in IoT applications is the automated replenishment process of fast moving consumer goods (FMCG) on shop shelves or home retail automation that allows for quick ordering of FMCG, where the IoT system is a part of smart packaging. For those reasons, a growing demand for cheap and tiny tension sensors has arisen. In this article, we propose a solution of a small flexible tension sensor fabricated in an amorphous InGaZnO (a-IGZO) thin-film process that can be integrated with other devices, e.g., near-field communications (NFC) or a barcode radio frequency identification (RFID) tag. The sensor was designed to magnify the slight internal changes in material properties caused by mechanical stress. These changes affect the dynamic electrical properties of specially designed inverters for a pair of ring oscillators, in which the frequencies become stress-dependent. In the article, we discuss and explain the approach to the optimum design of a ring oscillator that manifests the highest sensitivity to mechanical stress. Full article
(This article belongs to the Section Electronic Sensors)
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16 pages, 7346 KiB  
Article
Deep-Learning-Aided RF Fingerprinting for NFC Relay Attack Detection
by Yifeng Wang, Junwei Zou and Kai Zhang
Electronics 2023, 12(3), 559; https://doi.org/10.3390/electronics12030559 - 21 Jan 2023
Cited by 9 | Viewed by 5840
Abstract
Near field communication (NFC) has been a widely used radiofrequency identification (RFID) technology, credited to its convenience and security features. However, the transmitted signals can be easily eavesdropped or relayed in an open wireless channel. One of the challenges is relay attack, where [...] Read more.
Near field communication (NFC) has been a widely used radiofrequency identification (RFID) technology, credited to its convenience and security features. However, the transmitted signals can be easily eavesdropped or relayed in an open wireless channel. One of the challenges is relay attack, where an attacker simply relays the signal and bypasses encryption or other means in the application layer. Prior works on relay attack countermeasures have focused on distance-bounding protocols or ambient-based solutions. This paper focuses on ISO/IEC 14443-A and proposes an NFC relay detection method based on RF fingerprinting of transmitted wireless signals in the physical layer. To this end, we first designed and implemented two realizations of NFC relay attacks, wired and wireless relays, and built an SDR-based testbed. We collected the normal and relayed signals of four NFC tags, and the answer to request type A (ATQA) segments were selected for RF fingerprinting. The created dataset comprised 66,366 samples, with four tags’ normal and wired relayed signals and the wireless relayed signals. The dataset was then fed into a deep CNN for training. Finally, our experiment results showed that the method effectively distinguished normal and relayed signals with a high accuracy of 99%, confirming that RF fingerprinting can be a promising countermeasure to NFC relay attacks. Full article
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16 pages, 1774 KiB  
Article
Overcoming Catch Data Collection Challenges and Traceability Implementation Barriers in a Sustainable, Small-Scale Fishery
by Alison Grantham, Ma. Raisa Pandan, Susan Roxas and Bryan Hitchcock
Sustainability 2022, 14(3), 1179; https://doi.org/10.3390/su14031179 - 20 Jan 2022
Cited by 7 | Viewed by 5327
Abstract
The seafood sector faces both socioeconomic and environmental sustainability challenges, as well as pressure to demonstrate progress from governments, NGOs, retailers, and consumers. To document data elements necessary in verifying key sustainability attributes and fishery progress, the sector needs to implement traceability systems [...] Read more.
The seafood sector faces both socioeconomic and environmental sustainability challenges, as well as pressure to demonstrate progress from governments, NGOs, retailers, and consumers. To document data elements necessary in verifying key sustainability attributes and fishery progress, the sector needs to implement traceability systems accessible to fishers and other vulnerable near-shore actors. Implementation must overcome a suite of technological, social, and economic barriers. We assessed and reviewed the efficacy of several approaches attempted in a Philippines yellowfin tuna (Thunnus albacares) fishery. The current prevailing approach is a centralized, analog method of catch recording, both broadly across the Philippines and specifically in this MSC-certified fishery, where they have implemented enumerator-facilitated catch certificate recording. The fishery has begun developing, testing, and piloting new decentralized digital models, including NFC cards, RFID tags, and an app-based smartphone catch data capture. All approaches encountered barriers to uptake, and the most recent estimates suggest up to 44% of the catch in the Philippines remains unreported. We discuss additional systemic considerations necessary to advance sustainability outcomes and their documentation through traceability systems in the seafood sector originating with small-scale fishers. Full article
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12 pages, 3104 KiB  
Article
A Passive, Skin-Attachable Multi-Sensing Patch Based on Semi-Liquid Alloy Ni-GaIn for Wireless Epidermal Signal Monitoring and Body Motion Capturing
by Shipeng Lin, Jiming Fang, Tianchen Ye, Yan Tao, Shengshun Duan and Jun Wu
Electronics 2021, 10(22), 2778; https://doi.org/10.3390/electronics10222778 - 13 Nov 2021
Cited by 2 | Viewed by 3238
Abstract
Wearable integrated systems that rely on liquid metal commonly require an extremely complicated, high-cost fabrication process, while lacking multiple sensing functions without conductive wires connected to external electronic systems. A multi-sensing wearable patch independent from sophisticated manufacturing method and excessive use of wires [...] Read more.
Wearable integrated systems that rely on liquid metal commonly require an extremely complicated, high-cost fabrication process, while lacking multiple sensing functions without conductive wires connected to external electronic systems. A multi-sensing wearable patch independent from sophisticated manufacturing method and excessive use of wires has yet to be developed. Herein, we introduce a wireless, battery-free, and skin-attachable patch with multiple sensing capacities, utilizing a low-budget, less time-consuming and design-customizable fabrication method. In an effort to achieve our goal, the general sensing system architecture is promoted, which consists of a semi-liquid alloy Ni-GaIn based strain sensor and a co-designed near-field-communication (NFC) tag integrating thermistor, photoresistor, as well as sensor interface circuits, enabling energy-autonomous power supply and wireless data transmission. In human volunteers, the patch was mounted on the skin surface to demonstrate real-time temperature and light intensity signal monitoring. Further evaluation of body motion capturing involved finger bending and swallowing, demonstrating the feasibility of practical applications in different scenarios. Continuous and simultaneous multi-type signal sensing using the wearable patch should enrich the dimensions of measurements of body response to daily activities, unveiling the potential for remote human health monitoring, advanced human–machine interfaces, and other applications of interest. Full article
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16 pages, 5367 KiB  
Article
Paper-Based Competitive Immunochromatography Coupled with an Enzyme-Modified Electrode to Enable the Wireless Monitoring and Electrochemical Sensing of Cotinine in Urine
by Nutcha Larpant, Pramod K. Kalambate, Tautgirdas Ruzgas and Wanida Laiwattanapaisal
Sensors 2021, 21(5), 1659; https://doi.org/10.3390/s21051659 - 28 Feb 2021
Cited by 17 | Viewed by 4459
Abstract
This paper proposes a combined strategy of using paper-based competitive immunochromatography and a near field communication (NFC) tag for wireless cotinine determination. The glucose oxidase labeled cotinine antibody specifically binds free cotinine in a sample, whereas the unoccupied antibody attached to BSA-cotinine at [...] Read more.
This paper proposes a combined strategy of using paper-based competitive immunochromatography and a near field communication (NFC) tag for wireless cotinine determination. The glucose oxidase labeled cotinine antibody specifically binds free cotinine in a sample, whereas the unoccupied antibody attached to BSA-cotinine at the test line on a lateral flow strip. The glucose oxidase on the strip and an assistant pad in the presence of glucose generated H2O2 and imposed the Ag oxidation on the modified electrode. This enabled monitoring of immunoreaction by either electrochemical measurement or wireless detection. Wireless sensing was realized for cotinine in the range of 100–1000 ng/mL (R2 = 0.96) in PBS medium. Undiluted urine samples from non-smokers exhibited an Ag-oxidation rate three times higher than the smoker’s urine samples. For 1:8 diluted urine samples (smokers), the proposed paper-based competitive immunochromatography coupled with an enzyme-modified electrode differentiated positive and negative samples and exhibited cotinine discrimination at levels higher than 12 ng/mL. This novel sensing platform can potentially be combined with a smartphone as a reader unit. Full article
(This article belongs to the Special Issue Lateral Flow Immunoassay: Advances and Applications)
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12 pages, 1920 KiB  
Letter
Battery-Free and Noninvasive Estimation of Food pH and CO2 Concentration for Food Monitoring Based on Pressure Measurement
by Thanh-Binh Nguyen, Trung-Hau Nguyen and Wan-Young Chung
Sensors 2020, 20(20), 5853; https://doi.org/10.3390/s20205853 - 16 Oct 2020
Cited by 12 | Viewed by 3017
Abstract
In this paper, we developed a battery-free system that can be used to estimate food pH level and carbon dioxide (CO2) concentration in a food package from headspace pressure measurement. While being stored, food quality degrades gradually as a function of [...] Read more.
In this paper, we developed a battery-free system that can be used to estimate food pH level and carbon dioxide (CO2) concentration in a food package from headspace pressure measurement. While being stored, food quality degrades gradually as a function of time and storage conditions. A food monitoring system is, therefore, essential to prevent the detrimental problems of food waste and eating spoilt food. Since conventional works that invasively measure food pH level and CO2 concentration in food packages have shown several disadvantages in terms of power consumption, system size, cost, and reliability, our study proposes a system utilizing package headspace pressure to accurately and noninvasively extract food pH level and CO2 concentration, which reflection food quality. To read pressure data in the food container, a 2.5 cm × 2.5 cm smart sensor tag was designed and integrated with near-field communication (NFC)-based energy harvesting technology for battery-free operation. To validate the reliability of the proposed extraction method, various experiments were conducted with different foods, such as pork, chicken, and fish, in two storage environments. The experimental results show that the designed system can operate in a fully passive mode to communicate with an NFC-enabled smartphone. High correlation coefficients of the headspace pressure with the food pH level and the headspace CO2 concentration were observed in all experiments, demonstrating the ability of the proposed system to estimate food pH level and CO2 concentration with high accuracy. A linear regression model was then trained to linearly fit the sensor data. To display the estimated results, we also developed an Android mobile application with an easy-to-use interface. Full article
(This article belongs to the Section Physical Sensors)
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