A Highly Sensitive Integrated a-Si:H Fluorescence Detector for Microfluidic Devices

2010 ◽  
Vol 1245 ◽  
Author(s):  
Toshihiro Kamei ◽  
Amane Shikanai
Keyword(s):  
Light Scattering ◽  
High Speed ◽  
Laser Light ◽  
Separation Efficiency ◽  
Limit Of Detection ◽  
Point Of Care ◽  
High Sensitivity ◽  
Laser Light Scattering ◽  
Fluorescent Labeling ◽  
Fluorescence Detector

AbstractMost of micromachined and/or integrated fluorescence detectors suffer from high limit of detection (LOD) compared to conventional optical system that consists of discrete optical components, which is mainly due to higher laser light scattering of integrated optics rather than detector sensitivity. In this work, we have reduced background (BG) photocurrent of an integrated hydrogenated amorphous Si (a-Si:H) fluorescence detector due to laser light scattering by nearly one order magnitude, significantly improving a LOD. The detection platform comprises a microlens and the annular fluorescence detector where a thick SiO2/Ta2O5 multilayer optical interference filter (>6 μm) is monolithically integrated on an a-Si:H pin photodiode. With a microfluidic capillary electrophoresis (CE) device mounted on the platform, the system is demonstrated to separate DNA restriction fragment digests (LOD: 58 pg/μL) as well as 2 nM of fluorescein-labeled oligomer (LOD: 240 pM) with high speed, high sensitivity and high separation efficiency. The integrated a-Si:H fluorescence detector exhibits high sensitivity for practical fluorescent labeling dyes as well as feasibility of monolithic integration with a laser diode, making it ideal for application to point-of-care microfluidic biochemical analysis.

scholarly journals Direct-RT-qPCR Detection of SARS-CoV-2 without RNA Extraction as Part of a COVID-19 Testing Strategy: From Sample to Result in One Hour

Diagnostics ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 605 ◽  
Author(s):  
Eva Kriegova ◽  
Regina Fillerova ◽  
Petr Kvapil
Keyword(s):  
High Throughput Screening ◽  
High Speed ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rna Extraction ◽  
Rna Isolation ◽  
High Sensitivity ◽  
Ease Of Use ◽  
Diagnostic Tools ◽  
Heat Inactivation

Due to the lack of protective immunity in the general population and the absence of effective antivirals and vaccines, the Coronavirus disease 2019 (COVID-19) pandemic continues in some countries, with local epicentres emerging in others. Due to the great demand for effective COVID-19 testing programmes to control the spread of the disease, we have suggested such a testing programme that includes a rapid RT-qPCR approach without RNA extraction. The Direct-One-Step-RT-qPCR (DIOS-RT-qPCR) assay detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in less than one hour while maintaining the high sensitivity and specificity required of diagnostic tools. This optimised protocol allows for the direct use of swab transfer media (14 μL) without the need for RNA extraction, achieving comparable sensitivity to the standard method that requires the time-consuming and costly step of RNA isolation. The limit of detection for DIOS-RT-qPCR was lower than seven copies/reaction, which translates to 550 virus copies/mL of swab. The speed, ease of use and low price of this assay make it suitable for high-throughput screening programmes. The use of fast enzymes allows RT-qPCR to be performed under standard laboratory conditions within one hour, making it a potential point-of-care solution on high-speed cycling instruments. This protocol also implements the heat inactivation of SARS-CoV-2 (75 °C for 10 min), which renders samples non-infectious, enabling testing in BSL-2 facilities. Moreover, we discuss the critical steps involved in developing tests for the rapid detection of COVID-19. Implementing rapid, easy, cost-effective methods can help control the worldwide spread of the COVID-19 infection.

Study on Initial Growth of Particles in Low-Pressure and Low-Power GeH4 RF Discharges Using the High-Sensitivity Photon-Counting Laser-Light-Scattering Method

1998 ◽  
Vol 37 (Part 2, No. 10B) ◽  
pp. L1264-L1267 ◽  
Author(s):  
Hiroharu Kawasaki ◽  
Kazutaka Sakamoto ◽  
Shinichi Maeda ◽  
Tsuyoshi Fukuzawa ◽  
Masaharu Shiratani ◽  
...  
Keyword(s):  
Light Scattering ◽  
Low Power ◽  
Laser Light ◽  
Photon Counting ◽  
High Sensitivity ◽  
Low Pressure ◽  
Laser Light Scattering ◽  
Scattering Method ◽  
Initial Growth ◽  
Rf Discharges

A high-speed particle-detection in a large area using line-laser light scattering

2015 ◽  
Vol 15 (8) ◽  
pp. 930-937 ◽  
Author(s):  
Min Su Kim ◽  
Hyeun-Seok Choi ◽  
Seung Hee Lee ◽  
Chanjoong Kim
Keyword(s):  
Light Scattering ◽  
High Speed ◽  
Laser Light ◽  
Laser Light Scattering ◽  
Large Area ◽  
Particle Detection

In-Situ Dual-Wavelength Ellipsometry and Light Scattering Monitoring of Si/Si1−xGex Heterostructures and Multiuantum Wells

1993 ◽  
Vol 324 ◽  
Author(s):  
C. Pickering ◽  
D.A.O. Hope ◽  
W.Y. Leong ◽  
D.J. Robbins ◽  
R. Greef
Keyword(s):  
Growth Rate ◽  
Light Scattering ◽  
Laser Light ◽  
Growth Period ◽  
Laser Light Scattering ◽  
Heterojunction Bipolar Transistor ◽  
Dual Wavelength ◽  
Multi Quantum Well ◽  
Refractive Index Data

AbstractIn-situ dual-wavelength ellipsometry and laser light scattering have been used to monitor growth of Si/Si1−x,Gex heterojunction bipolar transistor and multi-quantum well (MQW) structures. The growth rate of B-doped Si0 8Ge0.2 has been shown to be linear, but that of As-doped Si is non-linear, decreasing with time. Refractive index data have been obtained at the growth temperature for x = 0.15, 0.20, 0.25. Interface regions ∼ 6-20Å thickness have been detected at hetero-interfaces and during interrupted alloy growth. Period-to-period repeatability of MQW structures has been shown to be ±lML.

scholarly journals Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors

2021 ◽  
Author(s):  
Franziska Beck ◽  
Carina Horn ◽  
Antje J. Baeumner
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Automatic Measurement ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Small Sample ◽  
Blood Protein ◽  
User Friendliness ◽  
Response Curves ◽  
Assay Protocol

AbstractElectrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL−1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL−1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL−1 in buffer and 4.7 ng∙mL−1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

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