scholarly journals Pocket Mercury-Vapour Detection System Employing a Preconcentrator Based on Au-TiO2 Nanomaterials

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8255
Author(s):  
Emiliano Zampetti ◽  
Paolo Papa ◽  
Andrea Bearzotti ◽  
Antonella Macagnano
Keyword(s):  
Quartz Crystal ◽  
Limit Of Detection ◽  
Detection System ◽  
Low Cost ◽  
Fast Response ◽  
Mercury Vapour ◽  
Detection Capability ◽  
Frequency Shifts ◽  
Tio2 Nanomaterials ◽  
Sampling Times

In environments polluted by mercury vapors that are potentially harmful to human health, there is a need to perform rapid surveys in order to promptly identify the sources of emission. With this aim, in this work, a low cost, pocket-sized portable mercury measurement system, with a fast response signal is presented. It consists of a preconcentrator, able to adsorb and subsequently release the mercury vapour detected by a quartz crystal microbalance (QCM) sensor. The preconcentrator is based on an adsorbing layer of titania/gold nanoparticles (TiO2NP/AuNPs), deposited on a micro-heater that acts as mercury thermal desorption. For the detection of the released mercury vapour, gold electrodes QCM (20 MHz) have been used. The experimental results, performed in simulated polluted mercury-vapour environments, showed a detection capability with a prompt response. In particular, frequency shifts (−118 Hz ± 2 Hz and −30 Hz ± 2 Hz) were detected at concentrations of 65 µg/m3 Hg0 and 30 µg/m3 Hg0, with sampling times of 60 min and 30 min, respectively. A system limit of detection (LOD) of 5 µg/m3 was evaluated for the 30 min sampling time.

scholarly journals A Real-Time Method for Improving Stability of Monolithic Quartz Crystal Microbalance Operating under Harsh Environmental Conditions

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4166
Author(s):  
Román Fernández ◽  
María Calero ◽  
Yolanda Jiménez ◽  
Antonio Arnau
Keyword(s):  
Real Time ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Limit Of Detection ◽  
Quartz Substrate ◽  
Low Cost ◽  
Discrete Wavelet ◽  
Reagent Consumption ◽  
Measurement Cell ◽  
The Stability

Monolithic quartz crystal microbalance (MQCM) has recently emerged as a very promising technology suitable for biosensing applications. These devices consist of an array of miniaturized QCM sensors integrated within the same quartz substrate capable of detecting multiple target analytes simultaneously. Their relevant benefits include high throughput, low cost per sensor unit, low sample/reagent consumption and fast sensing response. Despite the great potential of MQCM, unwanted environmental factors (e.g., temperature, humidity, vibrations, or pressure) and perturbations intrinsic to the sensor setup (e.g., mechanical stress exerted by the measurement cell or electronic noise of the characterization system) can affect sensor stability, masking the signal of interest and degrading the limit of detection (LoD). Here, we present a method based on the discrete wavelet transform (DWT) to improve the stability of the resonance frequency and dissipation signals in real time. The method takes advantage of the similarity among the noise patterns of the resonators integrated in an MQCM device to mitigate disturbing factors that impact on sensor response. Performance of the method is validated by studying the adsorption of proteins (neutravidin and biotinylated albumin) under external controlled factors (temperature and pressure/flow rate) that simulate unwanted disturbances.

scholarly journals Immobilization of DNA probes on a high frequency piezoelectric biosensor

DYNA ◽  
2020 ◽  
Vol 87 (212) ◽  
pp. 163-168
Author(s):  
Camilo Ortiz Monsalve ◽  
Jorge Mario Guerra González ◽  
Marisol Jaramillo Grajales
Keyword(s):  
Real Time ◽  
High Frequency ◽  
Quartz Crystal ◽  
Low Cost ◽  
Fast Response ◽  
Dna Probes ◽  
Self Assembled Monolayers ◽  
Saturation Point ◽  
Assembled Monolayers ◽  
Quartz Crystal Microbalances

In recent years, researchers have taken to biosensors as effective tools for detection due to their portability, low-cost, fast response, and practicality. Piezoelectricity gave way to quartz crystal microbalances (QCM), of which high-frequency QCMs (HFF-QCM 100MHz) are still being researched. In this paper, we use DNA immobilization on a HFF-QCM via self-assembled monolayers (SAM) technique. Immobilization was initially verified with ATR-FTIR. Then, DNA was immobilized in real time on the HFF-QCM crystals. A variation in the phase of the signal suggests fixation of DNA to the surface, in accordance with ATR-FTIR results. A density of 629 ng/cm2 was computed. Also, a positive correlation between immobilized DNA and DNA concentration, and the appearance of a saturation point between 1 and 5 μM were shown after analysis of different DNA concentrations.

scholarly journals Determination of Uric Acid in Artificial Saliva with Compact AMP3291 Reader and Au Nanoparticles Modified Electrode

Chemosensors ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 73
Author(s):  
Jessica Piedras ◽  
Rocio B. Dominguez ◽  
Juan Manuel Gutiérrez
Keyword(s):  
Uric Acid ◽  
Limit Of Detection ◽  
Artificial Saliva ◽  
Low Cost ◽  
Fast Response ◽  
The Body ◽  
Acquisition Time ◽  
Operational Parameters ◽  
Renal Disorder ◽  
Improved Performance

Uric acid (UA) is a residual product of purines in the body and has been proposed as a valuable biomarker for Diabetes Mellitus, renal disorder, hypertension and preeclampsia. This work presents a sensing platform for nonenzymatic UA detection using a screen-printed electrode modified with gold nanoparticles (SPE-AuNps) operated with the compact and low-cost amperometric reader AMP3291. This laboratory-made instrument was designed using the analog front end LMP91000 and the microcontroller ESP32; the operational parameters like working potential, acquisition time and dynamic measuring range were configured for UA detection. The whole sensing system (AMP3291+ SPE-AuNps) was evaluated for nonenzymatic sensing of UA, showing a fast response time of 3.5 s, a sensitivity of 0.022 μA·μM−1, a linear range from 20 to 200 μM (R2 = 0.993) and a limit of detection of 11.91 μM. Throughout, a piece of commercial equipment was used for validation and noticeably the measurements with the AMP3291-based platform showed improved performance, indicating the feasibility of the developed instrument for UA monitoring and potentially for in situ decentralized applications. Finally, artificial saliva was used as model medium exhibiting interesting analytical parameters, encouraging to consider the reported system as a potentially valuable tool for monitoring UA for clinical applications in resource-limited settings.

scholarly journals Microfluidic Raman Sensing Using a Single Ring Negative Curvature Hollow Core Fiber

Biosensors ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 430
Author(s):  
Xinyu Wang ◽  
Shuguang Li ◽  
Shoufei Gao ◽  
Yingying Wang ◽  
Pu Wang ◽  
...  
Keyword(s):  
Negative Curvature ◽  
Limit Of Detection ◽  
Detection System ◽  
Low Cost ◽  
Coupling Efficiency ◽  
Solid Core ◽  
Hollow Core ◽  
Single Ring ◽  
Excitation Laser ◽  
Core Fiber

A compact microfluidic Raman detection system based on a single-ring negative-curvature hollow-core fiber is presented. The system can be used for in-line qualitative and quantitative analysis of biochemicals. Both efficient light coupling and continuous liquid injection into the hollow-core fiber were achieved by creating a small gap between a solid-core fiber and the hollow-core fiber, which were fixed within a low-cost ceramic ferrule. A coupling efficiency of over 50% from free-space excitation laser to the hollow core fiber was obtained through a 350 μm-long solid-core fiber. For proof-of-concept demonstration of bioprocessing monitoring, a series of ethanol and glucose aqueous solutions at different concentrations were used. The limit of detection achieved for the ethanol solutions with our system was ~0.04 vol.% (0.32 g/L). Such an all-fiber microfluidic device is robust, provides Raman measurements with high repeatability and reusability, and is particularly suitable for the in-line monitoring of bioprocesses.

In-Line Moisture Monitoring in Semiconductor Process Gases by a Reactive-Metal-Coated Quartz Crystal Microbalance

1997 ◽  
Vol 40 (2) ◽  
pp. 43-48
Author(s):  
Jian Wei ◽  
John Pillion ◽  
Chi Hoang
Keyword(s):  
Quartz Crystal Microbalance ◽  
Distribution System ◽  
Quartz Crystal ◽  
Limit Of Detection ◽  
Fast Response ◽  
Ionization Mass ◽  
Reactive Metal ◽  
Process Gas ◽  
Moisture Detection ◽  
Pressure Ionization Mass Spectrometry

A new in-line sensor for trace moisture monitoring has been developed based on a piezoelectric quartz crystal microbalance (QCM) coated with a reactive metal thin film. The properties of the metal coating and QCM allow the sensor to have fast response and fast recovery to moisture in the process gas stream. The properties of the metal-coated QCM also allow the sensor to be compact so it can be in-line in the gas distribution system and readily integrated into the process tools. This paper presents the principle of moisture detection using this technology. The experimental results of accuracy, limit of detection (< 1 ppb), and error analysis of this sensor in parallel with atmospheric pressure ionization mass spectrometry (APIMS) are presented. The experimental setup and procedures are described. The effect of an upstream gas purifier on its rate of response was also studied and the results are presented and discussed. The applications of this technology in semiconductor processing are briefly mentioned.

scholarly journals Visual and Rapid Diagnosis of Neisseria gonorrhoeae Using Loop-Mediated Isothermal Amplification Combined With a Polymer Nanoparticle–Based Biosensor in Clinical Application

2021 ◽  
Vol 8 ◽  
Author(s):  
Xu Chen ◽  
Qingxue Zhou ◽  
Xueli Wu ◽  
Shuoshi Wang ◽  
Rui Liu ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Point Of Care ◽  
Low Cost ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Global Public Health ◽  
Fixed Temperature ◽  
Polymer Nanoparticle ◽  
Loop Mediated Isothermal Amplification

Neisseriagonorrhoeae is a host-adapted human pathogen that causes sexually transmitted gonorrhea and remains to be a serious global public health challenge, especially in low- and middle-income regions. It is vital to devise a reliable, simple, cost-saving, and easy-to-use assay for detecting the N. gonorrhoeae agent. In the current study, we firstly report a novel approach, loop-mediated isothermal amplification linked with a polymer nanoparticle–based biosensor (LAMP-PNB), that was used for identifying N. gonorrhoeae in clinical samples. The results showed that the LAMP primers based on the orf1 gene were valid for development of the N. gonorrhoeae-LAMP-PNB assay. The detection system with optimal conditions could be performed at a fixed temperature of 64°C for 40 min. The whole process, including genomic DNA preparation (approximately 10 min), LAMP reaction (40 min), and PNB reporting (approximately 2 min), could be accomplished within 60 min. The limit of detection (LoD) of the N. gonorrhoeae-LAMP-PNB assay was 50 copies per test. The specificity of the current assay was 100%, and no cross-reactions to non–N. gonorrhoeae isolates were observed. These results confirmed that the N. gonorrhoeae-LAMP-PNB technique is a reliable, specific, sensitive, rapid, low-cost, and easy-to-use method for detecting gonococci isolates. More importantly, this assay has great potential to develop a point-of-care (POC) testing method in clinical practice, especially in resource-constrained regions.

scholarly journals A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guanhua Xun ◽  
Stephan Thomas Lane ◽  
Vassily Andrew Petrov ◽  
Brandon Elliott Pepa ◽  
Huimin Zhao
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Volume ◽  
N Gene ◽  
Testing System ◽  
Target Sequence ◽  
One Pot ◽  
Sequence Detection ◽  
Highly Sensitive ◽  
Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

scholarly journals Validation of a Novel Diagnostic Approach Combining the VersaTREK™ System for Recovery and Real-Time PCR for the Identification of Mycobacterium chimaera in Water Samples

2021 ◽  
Vol 9 (5) ◽  
pp. 1031
Author(s):  
Roberto Zoccola ◽  
Alessia Di Blasio ◽  
Tiziana Bossotto ◽  
Angela Pontei ◽  
Maria Angelillo ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Limit Of Detection ◽  
Detection System ◽  
Bacterial Load ◽  
Microbial Control ◽  
Hospital Setting ◽  
Sample Volume ◽  
Analytical Sensitivity ◽  
Initial Water

Mycobacterium chimaera is an emerging pathogen associated with endocarditis and vasculitis following cardiac surgery. Although it can take up to 6–8 weeks to culture on selective solid media, culture-based detection remains the gold standard for diagnosis, so more rapid methods are urgently needed. For the present study, we processed environmental M. chimaera infected simulates at volumes defined in international guidelines. Each preparation underwent real-time PCR; inoculates were placed in a VersaTREK™ automated microbial detection system and onto selective Middlebrook 7H11 agar plates. The validation tests showed that real-time PCR detected DNA up to a concentration of 10 ng/µL. A comparison of the isolation tests showed that the PCR method detected DNA in a dilution of ×102 CFU/mL in the bacterial suspensions, whereas the limit of detection in the VersaTREK™ was <10 CFU/mL. Within less than 3 days, the VersaTREK™ detected an initial bacterial load of 100 CFU. The detection limit did not seem to be influenced by NaOH decontamination or the initial water sample volume; analytical sensitivity was 1.5 × 102 CFU/mL; positivity was determined in under 15 days. VersaTREK™ can expedite mycobacterial growth in a culture. When combined with PCR, it can increase the overall recovery of mycobacteria in environmental samples, making it potentially applicable for microbial control in the hospital setting and also in environments with low levels of contamination by viable mycobacteria.

scholarly journals Rapid and Sensitive Detection of miRNA Based on AC Electrokinetic Capacitive Sensing for Point-of-Care Applications

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3985
Author(s):  
Nan Wan ◽  
Yu Jiang ◽  
Jiamei Huang ◽  
Rania Oueslati ◽  
Shigetoshi Eda ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Clinical Diagnostics ◽  
Detection Methods ◽  
Capacitive Sensing ◽  
Application Potential ◽  
Mirna Detection ◽  
Mirna 25 ◽  
Low Sensitivity

A sensitive and efficient method for microRNAs (miRNAs) detection is strongly desired by clinicians and, in recent years, the search for such a method has drawn much attention. There has been significant interest in using miRNA as biomarkers for multiple diseases and conditions in clinical diagnostics. Presently, most miRNA detection methods suffer from drawbacks, e.g., low sensitivity, long assay time, expensive equipment, trained personnel, or unsuitability for point-of-care. New methodologies are needed to overcome these limitations to allow rapid, sensitive, low-cost, easy-to-use, and portable methods for miRNA detection at the point of care. In this work, to overcome these shortcomings, we integrated capacitive sensing and alternating current electrokinetic effects to detect specific miRNA-16b molecules, as a model, with the limit of detection reaching 1.0 femto molar (fM) levels. The specificity of the sensor was verified by testing miRNA-25, which has the same length as miRNA-16b. The sensor we developed demonstrated significant improvements in sensitivity, response time and cost over other miRNA detection methods, and has application potential at point-of-care.

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