Rapid, label-free, and sensitive point-of-care testing of anti-SARS-CoV-2 IgM/IgG using all-fiber Fresnel reflection microfluidic biosensor

The integration of microfluidics with advanced biosensor technologies offers tremendous advantages such as smaller sample volume requirement and precise handling of samples and reagents, for developing affordable point-of-care testing methodologies that could be used in hospitals for monitoring patients. However, the success and popularity of point-of-care diagnosis lies with the generation of instantaneous and reliable results through in situ tests conducted in a painless, non-invasive manner. This work presents the development of a simple, hybrid integrated optical microfluidic biosensor for rapid detection of analytes in test samples. The proposed biosensor works on the principle of colorimetric optical absorption, wherein samples mixed with suitable chromogenic substrates induce a color change dependent upon the analyte concentration that could then be detected by the absorbance of light in its path length. This optical detection scheme has been hybrid integrated with an acoustofluidic micromixing unit to enable uniform mixing of fluids within the device. As a proof-of-concept, we have demonstrated the real-time application of our biosensor format for the detection of potassium in whole saliva samples. The results show that our lab-on-a-chip technology could provide a useful strategy in biomedical diagnoses for rapid analyte detection towards clinical point-of-care testing applications.

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Compact multichannel spectroscopic label-free biosensor platform for plant diseases point-of-care testing (POCT)

Biophotonics in Point-of-Care ◽

10.1117/12.2553216 ◽

2020 ◽

Author(s):

Jurij Hastanin ◽

Cedric Lenaerts ◽

Patrick Gailly ◽

Frédéric Rabecki ◽

Aline Roobroeck ◽

...

Keyword(s):

Point Of Care ◽

Plant Diseases ◽

Label Free ◽

Point Of Care Testing

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Surface Potential-Controlled Oscillation in FET-Based Biosensors

Sensors ◽

10.3390/s21061939 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1939 ◽

Cited By ~ 1

Author(s):

Ji Hyun Kim ◽

Seong Jun Park ◽

Jin-Woo Han ◽

Jae-Hyuk Ahn

Keyword(s):

Surface Potential ◽

Threshold Voltage ◽

Oscillation Frequency ◽

Point Of Care ◽

Ring Oscillator ◽

Ph Sensing ◽

Label Free ◽

Point Of Care Testing ◽

Electrical Measurements ◽

Readout Circuits

Field-effect transistor (FET)-based biosensors have garnered significant attention for their label-free electrical detection of charged biomolecules. Whereas conventional output parameters such as threshold voltage and channel current have been widely used for the detection and quantitation of analytes of interest, they require bulky instruments and specialized readout circuits, which often limit point-of-care testing applications. In this study, we demonstrate a simple conversion method that transforms the surface potential into an oscillating signal as an output of the FET-based biosensor. The oscillation frequency is proposed as a parameter for FET-based biosensors owing to its intrinsic advantages of simple and compact implementation of readout circuits as well as high compatibility with neuromorphic applications. An extended-gate biosensor comprising an Al2O3-deposited sensing electrode and a readout transistor is connected to a ring oscillator that generates surface potential-controlled oscillation for pH sensing. Electrical measurement of the oscillation frequency as a function of pH reveals that the oscillation frequency can be used as a sensitive and reliable output parameter in FET-based biosensors for the detection of chemical and biological species. We confirmed that the oscillation frequency is directly correlated with the threshold voltage. For signal amplification, the effects of circuit parameters on pH sensitivity are investigated using different methods, including electrical measurements, analytical calculations, and circuit simulations. An Arduino board to measure the oscillation frequency is integrated with the proposed sensor to enable portable and real-time pH measurement for point-of-care testing applications.

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A rotationally focused flow (RFF) microfluidic biosensor by density difference for early-stage detectable diagnosis

Scientific Reports ◽

10.1038/s41598-021-88647-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Noori Kim ◽

Kyungsup Han ◽

Pei-Chen Su ◽

Insup Kim ◽

Yong-Jin Yoon

Keyword(s):

Early Detection ◽

Optical Sensors ◽

Early Stage ◽

Point Of Care ◽

Low Cost ◽

Ease Of Use ◽

Wavelength Shift ◽

Label Free ◽

Protein Biomarkers ◽

Microfluidic Biosensor

AbstractLabel-free optical biosensors have received tremendous attention in point-of-care testing, especially in the emerging pandemic, COVID-19, since they advance toward early-detection, rapid, real-time, ease-of-use, and low-cost paradigms. Protein biomarkers testings require less sample modification process compared to nucleic-acid biomarkers’. However, challenges always are in detecting low-concentration for early-stage diagnosis. Here we present a Rotationally Focused Flow (RFF) method to enhance sensitivity(wavelength shift) of label-free optical sensors by increasing the detection probability of protein-based molecules. The RFF is structured by adding a less-dense fluid to focus the target-fluid in a T-shaped microchannel. It is integrated with label-free silicon microring resonators interacting with biotin-streptavidin. The suggested mechanism has demonstrated 0.19 fM concentration detection along with a significant magnitudes sensitivity enhancement compared to single flow methods. Verified by both CFD simulations and fluorescent flow-experiments, this study provides a promising proof-of-concept platform for next-generation lab-on-a-chip bioanalytics such as ultrafast and early-detection of COVID-19.

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Hemocompatible Electrochemical Sensors for Continuous Monitoring of Blood Parameters

Engineering Proceedings ◽

10.3390/i3s2021dresden-10174 ◽

2021 ◽

Vol 6 (1) ◽

pp. 19

Author(s):

Sascha Balakin ◽

Bergoi Ibarlucea ◽

Dmitry Belyaev ◽

Larysa Baraban ◽

Stefanie Hänsel ◽

...

Keyword(s):

Continuous Monitoring ◽

Electrochemical Sensors ◽

Ex Vivo ◽

Point Of Care ◽

Blood Parameters ◽

Implantable Sensors ◽

Label Free ◽

Point Of Care Testing ◽

The Future ◽

Giant Step

The real-time monitoring of physiological parameters is essential for point-of-care testing. While nowadays routine tests are done through ex vivo analysis on frequently extracted blood, placing implantable sensors monitoring key blood parameters such as lactate, glucose, ions, and oxygen would mean a giant step forward in the care of critically ill patients, improving the response time in emergencies and diminishing the invasiveness of the measurements. The recent advances in microelectronics and nanotechnology are a promising technology enabling moving in that direction. The goal of our work is to develop arrays of electrochemical sensors with selective and hemocompatible coatings, allowing for the future implementation of such measurements in patients. We perform the analysis of blood parameters in a label-free and electrochemical manner which is compatible with the inevitable miniaturization in a real application. The tuneable composition of the layer will allow to pursue further applications in the future by modification of the receptor molecules and their concentrations.

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