scholarly journals Electro-Optical Biosensor Based on Embedded Double-Monolayer of Graphene Capacitor in Polymer Technology

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3564
Author(s):  
Ary V. R. Portes ◽  
Ana J. L. Martins ◽  
Jesus Alvarez Guerrero ◽  
Mauricio M. Carvalho ◽  
Ferney O. Amaya-Fernandez ◽  
...  
Keyword(s):  
Refractive Index ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Biosensor ◽  
Phase Changes ◽  
Monolayer Graphene ◽  
Interaction Length ◽  
Graphene Layers ◽  
Electro Optic ◽  
Large Phase

In this work, we present an interferometric polymer-based electro-optical device, integrated with an embedded double-monolayer graphene capacitor for biosensing applications. An external voltage across the capacitor applies an electric field to the graphene layers modifying their surface charge density and the Fermi level position in these layers. This in turn changes the electro-optic properties of the graphene layers making absorption in the waveguide tunable with external voltages. Simultaneously, it is possible to appreciate that this phenomenon contributes to the maximization of the light-graphene interaction by evanescent wave in the sensing area. As a result, it is obtained large phase changes at the output of the interferometer, as a function of small variations in the refractive index in the cladding area, which significantly increasing the sensitivity of the device. The optimum interaction length obtained was 1.24 cm considering a cladding refractive index of 1.33. An absorption change of 129 dB/mm was demonstrated. This result combined with the photonic device based on polymer technology may enable a low-cost solution for biosensing applications in Point of Care (PoC) platform.

scholarly journals Preparation and Characterization of Freely-Suspended Graphene Nanomechanical Membrane Devices with Quantum Dots for Point-of-Care Applications

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 104 ◽  
Author(s):  
Gorkem Memisoglu ◽  
Burhan Gulbahar ◽  
Ruben Fernandez Bello
Keyword(s):  
Quantum Dots ◽  
Point Of Care ◽  
Low Cost ◽  
Resonance Energy ◽  
Optical Emission ◽  
Experimental Methodology ◽  
Vibrational Properties ◽  
Suspended Graphene ◽  
Graphene Layers ◽  
Freely Suspended

We demonstrate freely suspended graphene-based nanomechanical membranes (NMMs) as acoustic sensors in the audible frequency range. Simple and low-cost procedures are used to fabricate NMMs with various thicknesses based on graphene layers grown by graphite exfoliation and solution processed graphene oxide. In addition, NMMs are grafted with quantum dots (QDs) for characterizing mass sensitive vibrational properties. Thickness, roughness, deformation, deflection and emissions of NMMs with attached QDs are experimented and analyzed by utilizing atomic force microscopy, Raman spectroscopy, laser induced deflection analyzer and spectrophotometers. Förster resonance energy transfer (FRET) is experimentally achieved between the QDs attached on NMMs and nearby glass surfaces for illustrating acousto-optic utilization in future experimental implementations combining vibrational properties of NMMs with optical emission properties of QDs. This property denoted as vibrating FRET (VFRET) is previously introduced in theoretical studies while important experimental steps are for the first time achieved in this study for future VFRET implementations. The proposed modeling and experimental methodology are promising for future novel applications such as NMM based biosensing, photonics and VFRET based point-of-care (PoC) devices.

scholarly journals Model of the broadband interferometric optical biosensor in a planar configuration

2020 ◽  
Vol 12 (2) ◽  
pp. 28
Author(s):  
Marek Blahut
Keyword(s):  
Refractive Index ◽  
Optical Sensor ◽  
High Performance ◽  
Low Cost ◽  
Complex Refractive Index ◽  
Broad Band ◽  
Single Mode ◽  
Optical Biosensor ◽  
Multimode Waveguide ◽  
Planar Configuration

The paper presents numerical studies of the model of an optical sensor based on interference of modes in planar one-dimensional step-index configuration, excited by a broadband light source from a selected spectral range. The refractive index variation of measured external surrounding affects the modal properties of multimode waveguide and the spectral field distribution at the output of the structure. The optical system described is designed to the analysis of biological substances. Full Text: PDF ReferencesM. Blahut, "Optical sensor in planar configuration based on multimode interference" Proc. SPIE, 10455, (2017). CrossRef K. Misiakos, et al, "Broad-band Mach-Zehnder interferometers as high performance refractive index sensors: Theory and monolithic implementation", Opt. Express, 22, 8856, (2014). CrossRef K. Gut, "Study of a Broadband Difference Interferometer Based on Low-Cost Polymer Slab Waveguides", Nanomaterials, 9, 729 (2019). CrossRef M. Nordstrom, et al, "Single-Mode Waveguides With SU-8 Polymer Core and Cladding for MOEMS Applications", J. Light. Techn., 25, 1284, (2007). CrossRef D. Segelstein, "The complex refractive index of water", M.S. Thesis, University of Missouri, (1981). DirectLink https://www.yokogawa.com/pl/solutions/products-platforms/ DirectLink

scholarly journals High-Sensitivity Terahertz Refractive Index Sensor in a Multilayered Structure with Graphene

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 500 ◽  
Author(s):  
Jiao Tang ◽  
Yunyang Ye ◽  
Jiao Xu ◽  
Zhiwei Zheng ◽  
Xiangliang Jin ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Sensitivity ◽  
Multilayered Structure ◽  
Monolayer Graphene ◽  
Refractive Index Sensor ◽  
Optical Resonance ◽  
Graphene Layers ◽  
Terahertz Band ◽  
Highly Sensitive ◽  
Terahertz Frequencies

In this paper, we propose a high-sensitivity optical sensor at terahertz frequencies based on a composite structure containing a one-dimensional photonic crystal (1D PC) coated with a layer of monolayer graphene. Between the 1D PC and the graphene there is a sensing medium. This high-sensitivity phenomenon originates from the excitation of optical resonance between the graphene and the 1D PC. The proposed sensor is highly sensitive to the Fermi energy of graphene, the thickness and refractive index of the sensing medium, and the number of graphene layers. By selecting appropriate parameters, the maximum sensitivity ( 407.36 ∘ / RIU ) is obtained. We believe the proposed configuration is promising for fabricating graphene-based biosensor- or gas-sensor devices and other related applications in the terahertz band.

scholarly journals Demonstration of a Low-Cost and Portable Optical Cavity-Based Sensor through Refractive Index Measurements

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2193 ◽  
Author(s):  
Donggee Rho ◽  
Caitlyn Breaux ◽  
Seunghyun Kim
Keyword(s):  
Refractive Index ◽  
Detection Method ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Differential Detection ◽  
Low Pass ◽  
Portable System ◽  
Simulation Results

An optical cavity-based sensor using a differential detection method has been proposed for point-of-care diagnostics. We developed a low-cost and portable optical cavity-based sensor system using a 3D printer and off-the-shelf optical components. In this paper, we demonstrate the sensing capability of the portable system through refractive index measurements. Fabricated optical cavity samples were tested using the portable system and compared to simulation results. A referencing technique and digital low pass filtering were applied to reduce the noise of the portable system. The measurement results match the simulation results well and show the improved linearity and sensitivity by employing the differential detection method. The limit of detection achieved was 1.73 × 10−5 Refractive Index Unit (RIU), which is comparable to other methods for refractive index sensing.

scholarly journals Validation of a point-of-care rapid diagnostic test for hepatitis C for use in resource-limited settings

2019 ◽  
Vol 11 (4) ◽  
pp. 314-315
Author(s):  
James S Leathers ◽  
Maria Belen Pisano ◽  
Viviana Re ◽  
Gertine van Oord ◽  
Amir Sultan ◽  
...  
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Rapid Diagnosis ◽  
Direct Acting Antivirals ◽  
Resource Limited Settings ◽  
Rapid Diagnosis Test ◽  
Resource Limited ◽  
Specificity And Sensitivity ◽  
Hcv Screening ◽  
Direct Acting

Abstract Background Treatment of HCV with direct-acting antivirals has enabled the discussion of HCV eradication worldwide. Envisioning this aim requires implementation of mass screening in resource-limited areas, usually constrained by testing costs. Methods We validated a low-cost, rapid diagnosis test (RDT) for HCV in three different continents in 141 individuals. Results The HCV RDT showed 100% specificity and sensitivity across different samples regardless of genotype or viral load (in samples with such information, 90%). Conclusions The HCV test validated in this study can allow for HCV screening in areas of need when properly used.

High-speed electro-optic switch using buried electrode structure in polymer Mach–Zehnder waveguide

2016 ◽  
Vol 30 (06) ◽  
pp. 1650063 ◽  
Author(s):  
Jingwen Sun ◽  
Jian Sun ◽  
Yunji Yi ◽  
Lucheng Qv ◽  
Shiqi Sun ◽  
...  
Keyword(s):  
Insertion Loss ◽  
Rise Time ◽  
High Speed ◽  
Low Cost ◽  
Characteristic Parameters ◽  
Electrode Structure ◽  
Processing Cost ◽  
Electro Optic ◽  
Disperse Red 1 ◽  
Excellent Photostability

A low-cost and high-speed electro-optic (EO) switch using the guest–host EO material Disperse Red 1/Polymethyl Methacrylate (DR1/PMMA) was designed and fabricated. The DR1/PMMA material presented a low processing cost, an excellent photostability and a large EO coefficient of 13.1 pm/V. To improve the performance of the switch, the in-plane buried electrode structure was introduced in the polymer Mach–Zehnder waveguide to improve the poling and modulating efficiency. The characteristic parameters of the waveguide and the electrodes were carefully designed and the fabrication process was strictly controlled. Under 1550 nm, the insertion loss of the device was 12.7 dB. The measured switching rise time and fall time of the switch were 50.00 ns and 54.29 ns, respectively.

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.

scholarly journals A glucose meter interface for point-of-care gene circuit-based diagnostics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Evan Amalfitano ◽  
Margot Karlikow ◽  
Masoud Norouzi ◽  
Katariina Jaenes ◽  
Seray Cicek ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Synthetic Biology ◽  
Molecular Diagnostics ◽  
Point Of Care ◽  
Low Cost ◽  
Gene Circuit ◽  
Reporter Systems ◽  
Glucose Meter ◽  
Pandemic Response ◽  
Glucose Output

AbstractRecent advances in cell-free synthetic biology have given rise to gene circuit-based sensors with the potential to provide decentralized and low-cost molecular diagnostics. However, it remains a challenge to deliver this sensing capacity into the hands of users in a practical manner. Here, we leverage the glucose meter, one of the most widely available point-of-care sensing devices, to serve as a universal reader for these decentralized diagnostics. We describe a molecular translator that can convert the activation of conventional gene circuit-based sensors into a glucose output that can be read by off-the-shelf glucose meters. We show the development of new glucogenic reporter systems, multiplexed reporter outputs and detection of nucleic acid targets down to the low attomolar range. Using this glucose-meter interface, we demonstrate the detection of a small-molecule analyte; sample-to-result diagnostics for typhoid, paratyphoid A/B; and show the potential for pandemic response with nucleic acid sensors for SARS-CoV-2.

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