scholarly journals Millimeter-Wave-Based Spoof Localized Surface Plasmonic Resonator for Sensing Glucose Concentration

Biosensors ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 358
Author(s):  
Yelim Kim ◽  
Ahmed Salim ◽  
Sungjoon Lim
Keyword(s):  
Millimeter Wave ◽  
Glucose Concentration ◽  
Glucose Monitoring ◽  
Microfluidic Channel ◽  
Microwave Frequency ◽  
Sample Volume ◽  
Small Sample ◽  
Localized Surface Plasmon ◽  
Minimum Detectable Concentration ◽  
Plasmonic Resonator

Glucose-monitoring sensors are necessary and have been extensively studied to prevent and control health problems caused by diabetes. Spoof localized surface plasmon (LSP) resonance sensors have been investigated for chemical sensing and biosensing. A spoof LSP has similar characteristics to an LSP in the microwave or terahertz frequency range but with certain advantages, such as a high-quality factor and improved sensitivity. In general, microwave spoof LSP resonator-based glucose sensors have been studied. In this study, a millimeter-wave-based spoof surface plasmonic resonator sensor is designed to measure glucose concentrations. The millimeter-wave-based sensor has a smaller chip size and higher sensitivity than microwave-frequency sensors. Therefore, the microfluidic channel was designed to be reusable and able to operate with a small sample volume. For alignment, a polydimethylsiloxane channel was simultaneously fabricated using a multilayer bonding film to attach the upper side of the pattern, which is concentrated in the electromagnetic field. This real-time sensor detects the glucose concentration via changes in the S11 parameter and operates at 28 GHz with an average sensitivity of 0.015669 dB/(mg/dL) within the 0–300 mg/dL range. The minimum detectable concentration and the distinguishable signal are 1 mg/dL and 0.015669 dB, respectively, from a 3.4 μL sample. The reusability and reproducibility were assessed through replicates.

scholarly journals Real-Time Noninvasive Measurement of Glucose Concentration Using a Modified Hilbert Shaped Microwave Sensor

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5525 ◽  
Author(s):  
Levon Odabashyan ◽  
Arsen Babajanyan ◽  
Zhirayr Baghdasaryan ◽  
Seungwan Kim ◽  
Jongchel Kim ◽  
...  
Keyword(s):  
Real Time ◽  
Glucose Concentration ◽  
Glucose Sensor ◽  
Near Field ◽  
Glucose Monitoring ◽  
Measurement Range ◽  
Minimum Detectable Concentration ◽  
Hilbert Curve ◽  
Interaction Technique ◽  
Detectable Concentration

We developed a microwave glucose sensor based on the modified first-order Hilbert curve design and measured glucose concentration in aqueous solutions by using a real-time microwave near-field electromagnetic interaction technique. We observed S21 transmission parameters of the sensor at resonant frequencies depend on the glucose concentration. We could determine the glucose concentration in the 0–250 mg/dL concentration range at an operating frequency of near 6 GHz. The measured minimum detectable signal was 0.0156 dB/(mg/dL) and the measured minimum detectable concentration was 1.92 mg/dL. The simulation result for the minimum detectable signal and the minimum detectable concentration was 0.0182 dB/(mg/dL) and 1.65 mg/dL, respectively. The temperature instability of the sensor for human glycemia in situ measurement range (27–34 °C for fingers and 36–40 °C for body temperature ranges) can be improved by the integration of the temperature sensor in the microwave stripline platform and the obtained data can be corrected during signal processing. The microwave signal–temperature dependence is almost linear with the same slope for a glucose concentration range of 50–150 mg/dL. The temperature correlation coefficient is 0.05 dB/°C and 0.15 dB/°C in 27–34 °C and 36–40 °C temperature range, respectively. The presented system has a cheap, easy fabrication process and has great potential for non-invasive glucose monitoring.

Microfluidic Devices for Enhancing the Sensitivity of ELISA Methods

2011 ◽  
Author(s):  
Debashis Dutta ◽  
Naoki Yanagisawa
Keyword(s):  
Limit Of Detection ◽  
Microfluidic Channel ◽  
Enzyme Reaction ◽  
Sample Volume ◽  
Biological Research ◽  
Minimum Detectable Concentration ◽  
Permeable Membrane ◽  
Microtiter Plates ◽  
Detectable Concentration ◽  
Elisa Technique

Enzyme-linked immunosorbent assays (ELISA) are critically important tools in biological research, allowing the presence and concentrations of a wide variety of key biochemical intermediates to be determined. While the signal amplification that is the core advantage of ELISA methods is impressive, it is nevertheless the case that it is insufficient for some particularly demanding challenges in terms of sensitivity, assay time, or sample size. In this paper, we discuss three different approaches developed in our laboratory that can improve the sensitivity of ELISA methods by 2–3 orders of magnitude. Two of these approaches have been shown to reduce the minimum detectable concentration of the target analyte in the system through trapping of the analyte species and the enzyme reaction product around a semi-permeable membrane. The third approach, on the other hand, focuses on reducing the sample volume requirement in these assays by implementing multiplex ELISA methods in a single microfluidic channel using the same enzyme label. This multiplex technique relies on the slow diffusion of the enzyme reaction product across adjacent assay segments for accurate quantitation and has been demonstrated to have a limit of detection substantially better than that of commercial microtiter plates. We believe the combination of these approaches could significantly extend the applicability of the ELISA technique to more challenging assays than is currently possible.

REAL-TIME SENSING THE GLUCOSE CONCENTRATION BY QUADRATIC-SHAPED MICROWAVE SENSOR

2019 ◽  
Vol 53 (2 (249)) ◽  
pp. 132-137
Author(s):  
B.A. Hovhannisyan ◽  
D.S. Hambaryan ◽  
L.A. Odabashyan ◽  
A.Zh. Babajanyan
Keyword(s):  
Linear Relationship ◽  
Glucose Concentration ◽  
Electromagnetic Interaction ◽  
Near Field ◽  
Glucose Monitoring ◽  
Minimum Detectable Concentration ◽  
Interaction Technique ◽  
Non Invasive ◽  
Microwave Sensor ◽  
Detectable Concentration

In this study we present a microwave sensor based on the quadratic-shape and designed for detecting glucose concentration in aqueous solutions by using a microwave near-field electromagnetic interaction technique. We found a linear relationship between the microwave $ S_{11} $ reflection coefficient of the suggested system and the concentration of glucose in solution. Due to this linear relationship we were able to determine the glucose concentration in the range of 0–250 mg/dL at an operating frequency near 3.6 GHz. The measured minimum detectable signal was 0.0044 dB/(mg/dL) and the measured minimum detectable concentration was 6.8 mg/dL. These results suggest that the system we offer has a high enough accuracy for non-contact glucose monitoring and provides a promising basis for developing a non-invasive glucometer.

scholarly journals Continuous glucose monitoring can disclose glucose fluctuation in advanced Parkinsonian syndromes

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Hiroyuki Todo
Keyword(s):  
Continuous Glucose Monitoring ◽  
Glucose Concentration ◽  
Small Sample Size ◽  
Glucose Monitoring ◽  
Lewy Bodies ◽  
Small Sample ◽  
Glucose Fluctuation ◽  
Blood Tests ◽  
Parkinsonian Syndromes ◽  
Routine Blood

Continuous glucose monitoring (CGM) is a method to examine glucose concentration in subcutaneous interstitial fluid sequentially. CGM can disclose glucose fluctuation (GF), which can be unrecognized in routine blood tests. A limited number of studies suggest advanced Parkinsonian syndromes (PS) is at risk of GF, however, the report of CGM in PS is scarce. We performed CGM for 72 h in 11 nondiabetic patients with advanced PS. The etiology was Parkinson’s disease, multiple system atrophy, progressive supranuclear palsy, or dementia with Lewy bodies. All participants were bedridden, elderly (≥65 year-old), and receiving enteral nutrition. The retrospective data was obtained after the removal of CGM device. In the glucose concentration, 9 (81.8%) participants showed nocturnal decline (≤70 mg/dL; 4 of them reached recordable limit of 40 mg/dL), and 6 (54.5%) participants showed remarkable elevation (≥200 mg/dL) postprandially. In the majority, these abnormalities were difficult to predict from routine blood tests. Standard deviation and mean of sequential glucose concentration were higher than those in precedent reports of young or middle-aged healthy controls. CGM in nondiabetic and elderly patients with advanced PS can disclose GF, with features of nocturnal decline and/or postprandial remarkable elevation of glucose concentration. Owing to limitations such as small sample size, heterogeneity of etiology, and retrospectivity of CGM data, further investigations are required.

Laboratory Evaluation of the GlucocardTM Blood Glucose Test Meter

1992 ◽  
Vol 38 (10) ◽  
pp. 2093-2095 ◽  
Author(s):  
B D Lewis
Keyword(s):  
Blood Glucose ◽  
Glucose Concentration ◽  
Blood Glucose Concentration ◽  
Test Strip ◽  
Sample Volume ◽  
Small Sample ◽  
Laboratory Evaluation ◽  
Self Monitoring ◽  
Blood Glucose Test ◽  
Blood Glucose Concentrations

Abstract The Glucocard (Kyoto Daiichi Kagaku) blood glucose meter is designed for self-monitoring of blood glucose concentrations in capillary blood through use of an electrochemical test strip. Evaluated in this laboratory, the Glucocard had CVs of 4.6%, 6.6%, and 3.5% at blood glucose concentrations of 2.4, 4.1, and 18.9 mmol/L, respectively. The meter's response varied linearly with blood glucose concentration between 2.2 and 27.8 mmol/L. Hemolysis, urate, ascorbate, and acetaminophen interfered by > 5%. Different hematocrits, in the range 0.20-0.70, did not affect the measured glucose concentration. Comparison with glucose results measured in whole blood with a NOVA Stat Profile 5 instrument yielded the following: Glucocard = 0.898 NOVA--0.184 (r = 0.995). The main advantages of the Glucocard are its small sample volume (5 microL), wide linear range, and fully automated sample-handling steps, which reduce user-related variability.

Effect of Small Sample Volume on Five Glucose Monitoring Systems

Diabetes Care ◽  
1996 ◽  
Vol 19 (8) ◽  
pp. 903-904 ◽  
Author(s):  
F. R. Velazquez ◽  
D. Bartholomew
Keyword(s):  
Glucose Monitoring ◽  
Sample Volume ◽  
Small Sample ◽  
Monitoring Systems ◽  
Small Sample Volume

scholarly journals Universal Stokes’s nanomechanical viscometer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Komal Chaudhary ◽  
Pooja Munjal ◽  
Kamal P. Singh
Keyword(s):  
Electric Field ◽  
Real Time ◽  
Sample Volume ◽  
Capillary Waves ◽  
Small Sample ◽  
Medical Applications ◽  
Rapid Measurement ◽  
Single Lens ◽  
Universal Applicability ◽  
Small Sample Volume

AbstractAlthough, many conventional approaches have been used to measure viscosity of fluids, most methods do not allow non-contact, rapid measurements on small sample volume and have universal applicability to all fluids. Here, we demonstrate a simple yet universal viscometer, as proposed by Stokes more than a century ago, exploiting damping of capillary waves generated electrically and probed optically with sub-nanoscale precision. Using a low electric field local actuation of fluids we generate quasi-monochromatic propagating capillary waves and employ a pair of single-lens based compact interferometers to measure attenuation of capillary waves in real-time. Our setup allows rapid measurement of viscosity of a wide variety of polar, non-polar, transparent, opaque, thin or thick fluids having viscosity values varying over four orders of magnitude from $$10^{0}{-}10^{4}~\text{mPa} \, \text{s}$$ 10 0 - 10 4 mPa s . Furthermore, we discuss two additional damping mechanisms for nanomechanical capillary waves caused by bottom friction and top nano-layer appearing in micro-litre droplets. Such self-stabilized droplets when coupled with precision interferometers form interesting microscopic platform for picomechanical optofluidics for fundamental, industrial and medical applications.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

scholarly journals A tandem giant magnetoresistance assay for one-shot quantification of clinically relevant concentrations of N-terminal pro-B-type natriuretic peptide in human blood

2021 ◽  
Author(s):  
Fanda Meng ◽  
Weisong Huo ◽  
Jie Lian ◽  
Lei Zhang ◽  
Xizeng Shi ◽  
...  
Keyword(s):  
Detection Limit ◽  
Giant Magnetoresistance ◽  
Dynamic Range ◽  
Point Of Care ◽  
Sample Volume ◽  
Small Sample ◽  
Broad Dynamic Range ◽  
Gmr Sensors ◽  
Gmr Sensor ◽  
Sample Volume Requirement

AbstractWe report a microfluidic sandwich immunoassay constructed around a dual-giant magnetoresistance (GMR) sensor array to quantify the heart failure biomarker NT-proBNP in human plasma at the clinically relevant concentration levels between 15 pg/mL and 40 ng/mL. The broad dynamic range was achieved by differential coating of two identical GMR sensors operated in tandem, and combining two standard curves. The detection limit was determined as 5 pg/mL. The assay, involving 53 plasma samples from patients with different cardiovascular diseases, was validated against the Roche Cobas e411 analyzer. The salient features of this system are its wide concentration range, low detection limit, small sample volume requirement (50 μL), and the need for a short measurement time of 15 min, making it a prospective candidate for practical use in point of care analysis.

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