scholarly journals Smart facemask for wireless CO2 monitoring

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
P. Escobedo ◽  
M. D. Fernández-Ramos ◽  
N. López-Ruiz ◽  
O. Moyano-Rodríguez ◽  
A. Martínez-Olmos ◽  
...  
Keyword(s):  
Chemical Sensor ◽  
Limit Of Detection ◽  
Near Field ◽  
Health Assessment ◽  
Smartphone Application ◽  
Preclinical Research ◽  
Flexible Battery ◽  
Sensing Platform ◽  
Potential Applicability ◽  
Community Transmission

AbstractThe use of facemasks by the general population is recommended worldwide to prevent the spread of SARS-CoV-2. Despite the evidence in favour of facemasks to reduce community transmission, there is also agreement on the potential adverse effects of their prolonged usage, mainly caused by CO2 rebreathing. Herein we report the development of a sensing platform for gaseous CO2 real-time determination inside FFP2 facemasks. The system consists of an opto-chemical sensor combined with a flexible, battery-less, near-field-enabled tag with resolution and limit of detection of 103 and 140 ppm respectively, and sensor lifetime of 8 h, which is comparable with recommended FFP2 facemask usage times. We include a custom smartphone application for wireless powering, data processing, alert management, results displaying and sharing. Through performance tests during daily activity and exercise monitoring, we demonstrate its utility for non-invasive, wearable health assessment and its potential applicability for preclinical research and diagnostics.

scholarly journals Paper-Based Competitive Immunochromatography Coupled with an Enzyme-Modified Electrode to Enable the Wireless Monitoring and Electrochemical Sensing of Cotinine in Urine

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1659
Author(s):  
Nutcha Larpant ◽  
Pramod K. Kalambate ◽  
Tautgirdas Ruzgas ◽  
Wanida Laiwattanapaisal
Keyword(s):  
Glucose Oxidase ◽  
Modified Electrode ◽  
Near Field ◽  
Electrochemical Measurement ◽  
Electrochemical Sensing ◽  
Urine Samples ◽  
Lateral Flow Strip ◽  
Wireless Monitoring ◽  
Sensing Platform ◽  
Combined Strategy

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.

Core-shell Cu@C@ZIF-8 composite: a high-performance electrode material for electrochemical sensing of nitrite with high selectivity and sensitivity

2021 ◽  
Author(s):  
Feng Gao ◽  
Xiaolong Tu ◽  
Yongfang Yu ◽  
Yansha Gao ◽  
Jin Zou ◽  
...  
Keyword(s):  
High Performance ◽  
High Selectivity ◽  
Limit Of Detection ◽  
Metal Organic Framework ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Core Shell ◽  
Zeolitic Imidazolate Framework ◽  
Sensing Platform ◽  
The Difference

Abstract Herein, an efficient electrochemical sensing platform is proposed for selective and sensitive detection of nitrite on the basis of Cu@C@Zeolitic imidazolate framework-8 (Cu@C@ZIF-8) heterostructure. Core-shell Cu@C@ZIF-8 composite was synthesized by pyrolysis of Cu-metal-organic framework@ZIF-8 (Cu-MOF@ZIF-8) in Ar atmosphere on account of the difference of thermal stability between Cu-MOF and ZIF-8. For the sensing system of Cu@C@ZIF-8, ZIF-8 with proper pore size allows nitrite diffuse through the shell, while big molecules cannot, which ensures high selectivity of the sensor. On the other hand, Cu@C as electrocatalyst promotes the oxidation of nitrite, thereby resulting high sensitivity of the sensor. Accordingly, the Cu@C@ZIF-8 based sensor presents excellent performance for nitrite detection, which achieves a wide linear response range of 0.1 µM to 300.0 µM, and a low limit of detection (LOD) of 0.033 µM. In addition, the Cu@C@ZIF-8 sensor possesses excellent stability and reproducibility, and was employed to quantify nitrite in sausage samples with recoveries of 95.45-104.80%.

Two Orders of Magnitude Improvement in the Detection Limit of Droplet-Based Micro-Magnetofluidics with Planar Hall Effect Sensors

2021 ◽  
Vol 6 (1) ◽  
pp. 47
Author(s):  
Julian Schütt ◽  
Rico Illing ◽  
Oleksii Volkov ◽  
Tobias Kosub ◽  
Pablo Nicolás Granell ◽  
...  
Keyword(s):  
Detection Limit ◽  
Hall Effect ◽  
State Of The Art ◽  
Limit Of Detection ◽  
Research Field ◽  
High Throughput Analysis ◽  
Planar Hall Effect ◽  
Biologically Relevant ◽  
Sensing Platform ◽  
Order Of Magnitude

The detection, manipulation, and tracking of magnetic nanoparticles is of major importance in the fields of biology, biotechnology, and biomedical applications as labels as well as in drug delivery, (bio-)detection, and tissue engineering. In this regard, the trend goes towards improvements of existing state-of-the-art methodologies in the spirit of timesaving, high-throughput analysis at ultra-low volumes. Here, microfluidics offers vast advantages to address these requirements, as it deals with the control and manipulation of liquids in confined microchannels. This conjunction of microfluidics and magnetism, namely micro-magnetofluidics, is a dynamic research field, which requires novel sensor solutions to boost the detection limit of tiny quantities of magnetized objects. We present a sensing strategy relying on planar Hall effect (PHE) sensors in droplet-based micro-magnetofluidics for the detection of a multiphase liquid flow, i.e., superparamagnetic aqueous droplets in an oil carrier phase. The high resolution of the sensor allows the detection of nanoliter-sized superparamagnetic droplets with a concentration of 0.58 mg cm−3, even when they are only biased in a geomagnetic field. The limit of detection can be boosted another order of magnitude, reaching 0.04 mg cm−³ (1.4 million particles in a single 100 nL droplet) when a magnetic field of 5 mT is applied to bias the droplets. With this performance, our sensing platform outperforms the state-of-the-art solutions in droplet-based micro-magnetofluidics by a factor of 100. This allows us to detect ferrofluid droplets in clinically and biologically relevant concentrations, and even in lower concentrations, without the need of externally applied magnetic fields.

scholarly journals Impedance Sensing Platform for Detection of the Food Pathogen Listeria monocytogenes

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 347 ◽  
Author(s):  
Maria Chiriacò ◽  
Ilaria Parlangeli ◽  
Fausto Sirsi ◽  
Palmiro Poltronieri ◽  
Elisabetta Primiceri
Keyword(s):  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Foodborne Pathogen ◽  
High Sensitivity ◽  
Primary Objective ◽  
Field Application ◽  
Impedance Sensing ◽  
Sensing Platform

A great improvement in food safety and quality controls worldwide has been achieved through the development of biosensing platforms. Foodborne pathogens continue to cause serious outbreaks, due to the ingestion of contaminated food. The development of new, sensitive, portable, high-throughput, and automated platforms is a primary objective to allow detection of pathogens and their toxins in foods. Listeria monocytogenes is one common foodborne pathogen. Major outbreaks of listeriosis have been caused by a variety of foods, including milk, soft cheeses, meat, fermented sausages, poultry, seafood and vegetable products. Due to its high sensitivity and easy setup, electrochemical impedance spectroscopy (EIS) has been extensively applied for biosensor fabrication and in particular in the field of microbiology as a mean to detect and quantify foodborne bacteria. Here we describe a miniaturized, portable EIS platform consisting of a microfluidic device with EIS sensors for the detection of L. monocytogenes in milk samples, connected to a portable impedance analyzer for on-field application in clinical and food diagnostics, but also for biosecurity purposes. To achieve this goal microelectrodes were functionalized with antibodies specific for L. monocytogenes. The binding and detection of L. monocytogenes was achieved in the range 2.2 × 103 cfu/mL to 1 × 102 with a Limit of Detection (LoD) of 5.5 cfu/mL.

scholarly journals Dissolved Carbon Dioxide Sensing Platform for Freshwater and Saline Water Applications: Characterization and Validation in Aquaculture Environments

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5513
Author(s):  
J.P. Mendes ◽  
L. Coelho ◽  
B. Kovacs ◽  
J.M.M.M. de Almeida ◽  
C.M. Pereira ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Limit Of Detection ◽  
Saline Water ◽  
Light Emitting Diode ◽  
Limit Of Quantification ◽  
Acid Media ◽  
Dissolved Carbon ◽  
Sensing Platform ◽  
Dissolved Carbon Dioxide ◽  
Colorimetric Indicator

A sensing configuration for the real-time monitoring, detection, and quantification of dissolved carbon dioxide (dCO2) was developed for aquaculture and other applications in freshwater and saline water. A chemical sensing membrane, based on a colorimetric indicator, is combined with multimode optical fiber and a dual wavelength light-emitting diode (LED) to measure the dCO2-induced absorbance changes in a self-referenced ratiometric scheme. The detection and processing were achieved with an embeded solution having a mini spectrometer and microcontroller. For optrode calibration, chemical standard solutions using sodium carbonate in acid media were used. Preliminary results in a laboratory environment showed sensitivity for small added amounts of CO2 (0.25 mg·L−1). Accuracy and response time were not affected by the type of solution, while precision was affected by salinity. Calibration in freshwater showed a limit of detection (LOD) and a limit of quantification (LOQ) of 1.23 and 1.87 mg·L−1, respectively. Results in saline water (2.5%) showed a LOD and LOQ of 1.05 and 1.16 mg·L−1, respectively. Generally, performance was improved when moving from fresh to saline water. Studies on the dynamics of dissolved CO2 in a recirculating shallow raceway system (SRS+RAS) prototype showed higher precision than the tested commercial sensor. The new sensor is a compact and robust device, and unlike other sensors used in aquaculture, stirring is not required for correct and fast detection. Tests performed showed that this new sensor has a fast accurate detection as well as a strong potential for assessing dCO2 dynamics in aquaculture applications.

scholarly journals Low-cost wireless power efficiency optimization of the NFC tag through switchable receiver antenna

2018 ◽  
Vol 5 (2) ◽  
pp. 87-96 ◽  
Author(s):  
Yi Zhao ◽  
Huaye Li ◽  
Saman Naderiparizi ◽  
Aaron Parks ◽  
Joshua R. Smith
Keyword(s):  
Power Efficiency ◽  
Low Cost ◽  
Near Field ◽  
Power Delivery ◽  
Wireless Power ◽  
Load Impedance ◽  
Communication Performance ◽  
Sensing Platform ◽  
Varied Range ◽  
Range Alignment

Near-field communication (NFC) readers, ubiquitously embedded in smartphones and other infrastructures can wirelessly deliver mW-level power to NFC tags. Our previous work NFC-wireless identification and sensing platform (WISP) proves that the generated NFC signal from an NFC enabled phone can power a tag (NFC-WISP) with display and sensing capabilities in addition to identification. However, accurately aligning and placing the NFC tag's antenna to ensure the high power delivery efficiency and communication performance is very challenging for the users. In addition, the performance of the NFC tag is not only range and alignment sensitive but also is a function of its run-time load impedance. This makes the execution of power-hungry tasks on an NFC tag (like the NFC-WISP) very challenging. Therefore, we explore a low-cost tag antenna design to achieve higher power delivered to the load (PDL) by utilizing two different antenna configurations (2-coil/3-coil). The two types of antenna configurations can be used to dynamically adapt to the requirements of varied range, alignment and load impedance in real-time, therefore, we achieve continuous high PDL and reliable communication. With the proposed method, we can, for example, turn a semi-passive NFC-WISP into a passive display tag in which an embedded 2.7″ E-ink screen can be updated robustly by a tapped NFC reader (e.g. an NFC-enable cell-phone) over a 3 seconds and within 1.5cm range.

Chemical traffic light: A self-calibrating naked-eye sensor for fluoride

2019 ◽  
Vol 23 (01n02) ◽  
pp. 117-124 ◽  
Author(s):  
Alessia D’Andrea ◽  
Giuseppe Pomarico ◽  
Sara Nardis ◽  
Roberto Paolesse ◽  
Corrado Di Natale ◽  
...  
Keyword(s):  
Low Cost ◽  
Aqueous Media ◽  
Smartphone Application ◽  
Fluoride Content ◽  
Color Variation ◽  
Fluoride Ion ◽  
Traffic Light ◽  
Naked Eye ◽  
Sensing Platform ◽  
Guideline Value

We report a low-cost sensing platform for effective naked-eye detection of fluoride ion in aqueous media. The sensor is based on silicon complex of 5,10,15-tritolylcorrole (SiTTCorr) deposited on paper support and designed in a particular way that permits it to perform in a unique sensing event an internal sensor self-calibration and subsequent analysis of fluoride ion in a concentration range from 20 [Formula: see text]g/L to 200 mg/L with a LOD 9 [Formula: see text]g/L, much lower than the WHO guideline value of 1.5 mg/L for fluoride in drinking water. The influence of tetradodecylammonium chloride (TDACl) anion exchanger addition to the performance of SiTTCorr-based sensors was studied and the sensor with optimal ionophore: exchanger [Formula: see text] 2:1 ratio demonstrated the highest sensitivity. The evident color variation of SiTTCorr-based optode from dark pink to intense green occurred upon addition of increasing concentrations of fluoride. A smartphone application equipped with home-written color intensity analysis software as a detector of developed sensor output permitted fluoride content quantification in bottled water and toothpaste samples. Moreover, since at the quantification step the SiTTCorr color variation was significant for the red component of visible light and increase of fluoride content evidently changed this color from red to yellow and then to green, the developed optode was compared to a kind of chemical traffic light, able to detect the presence of fluoride in permitted, borderline or dangerous concentrations, respectively.

Time-resolved quenched phosphorescence detection of chromate in water samples using paired-ion reversed phase high performance liquid chromatography

1987 ◽  
Vol 65 (5) ◽  
pp. 965-969 ◽  
Author(s):  
Robert A. Baumann ◽  
Marry Schreurs ◽  
Cees Gooijer ◽  
Nel H. Velthorst ◽  
Roland W. Frei
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Water Samples ◽  
High Performance ◽  
Limit Of Detection ◽  
Tap Water ◽  
Reversed Phase ◽  
Time Resolved ◽  
Potential Applicability ◽  
Surface Water Samples

The feasibility of time-resolved quenched phosphorescence as a detection method for chromate based on paired-ion reversed phase high performance liquid chromatography is shown. After separation detection is achieved by monitoring the time-resolved phosphorescence signal of biacetyl at 515 nm. Optimization of the time-resolution parameters of the luminescence detector results in a limit of detection of 1.4 × 10−7 M (2 ng on column) for chromate standard solutions. The linearity of the method is three orders of magnitude. Chromatograms of tap water and surface water samples spiked with chromate show the potential applicability of the method for real samples.

scholarly journals Use of Dispersive Liquid-Liquid Microextraction and UV-Vis Spectrophotometry for the Determination of Cadmium in Water Samples

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
J. Pérez-Outeiral ◽  
E. Millán ◽  
R. Garcia-Arrona
Keyword(s):  
Water Samples ◽  
Limit Of Detection ◽  
Experimental Conditions ◽  
Cadmium Determination ◽  
A Value ◽  
Relative Standard ◽  
Potential Applicability ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

A simple and inexpensive method for cadmium determination in water using dispersive liquid-liquid microextraction and ultraviolet-visible spectrophotometry was developed. In order to obtain the best experimental conditions, experimental design was applied. Calibration was made in the range of 10–100 μg/L, obtaining good linearity (R2 = 0.9947). The obtained limit of detection based on calibration curve was 8.5 μg/L. Intra- and interday repeatability were checked at two levels, obtaining relative standard deviation values from 9.0 to 13.3%. The enrichment factor had a value of 73. Metal interferences were also checked and tolerable limits were evaluated. Finally, the method was applied to cadmium determination in real spiked water samples. Therefore, the method showed potential applicability for cadmium determination in highly contaminated liquid samples.

scholarly journals Dielectric Nanohole Array Metasurface For High-Resolution Near-Field Sensing and Imaging

2020 ◽  
Author(s):  
Donato Conteduca ◽  
Isabel Barth ◽  
Giampaolo Pitruzzello ◽  
Christopher Reardon ◽  
Emiliano Martins ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Limit Of Detection ◽  
Near Field ◽  
Nanohole Array ◽  
Trade Off ◽  
High Q ◽  
Biochemical Sensing ◽  
Optical Modes ◽  
Field Sensing ◽  
Q Factors

Abstract Dielectric metasurfaces support resonances that are widely explored both for far-field wavefront shaping and for near-field sensing and imaging. Their design explores the interplay between localised Mie resonances and extended Bragg resonances, with a typical trade-off between Q-factor and light localisation; high Q-factors are desirable for refractive index sensing while localisation is desirable for imaging resolution. Here, we show that a dielectric metasurface consisting of a nanohole array in amorphous silicon provides a favourable trade-off between these requirements. We have designed and realised the metasurface to support two optical modes both with sharp Fano resonances that exhibit relatively high Q factors and strong spatial confinement, thereby concurrently optimizing the device for both imaging and biochemical sensing. For the sensing application, we demonstrate a limit of detection (LOD) as low as 1pg/ml for Immunoglobulin G (IgG); for resonant imaging, we demonstrate a spatial resolution below 1µm and clearly resolve individual E.coli bacteria. The combined low LOD and high spatial resolution opens new opportunities for extending cellular studies into the realm of microbiology, e.g. for studying antimicrobial susceptibility.

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