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      An In-Vitro Optical Sensor Designed to Estimate Glycated Hemoglobin Levels

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          Abstract

          The purpose of this research was to design an optical sensor for evaluating glycated hemoglobin (HbA1c) percentages in hemoglobin. The A1c sensors available in the market use invasive methods, while our device offers the possibility of non-invasive monitoring of HbA1c levels in diabetic patients. A prototype is assembled using two light emitting diodes with peak emission wavelengths of 535 nm and 593 nm, a photodiode, and a microcontroller. The proposed sensor measures the transmitted intensity in the form of an output voltage. We devise an approach to estimate the percentage of HbA1c in hemoglobin for a given solution. This estimation is based on the relative change in absorbance due to change in path length and molar absorption coefficients of hemoglobin and HbA1c, at the two wavelengths. We calculate the molar absorption coefficient of HbA1c at 535 nm and 593 nm wavelengths using the sensor, which is performed by a multiple variable regression analysis algorithm fed through the microcontroller. Specifically, the sensor output voltage with respect to the sample concentration is fitted to an exponentially decaying equation model. We used a commercial chemical assay called Control FD Glycohemoglobin A1c with known percentage HbA1c levels to verify our device measurements.

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          Most cited references26

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          Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics

          Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.
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            Spectroscopic determination of tryptophan and tyrosine in proteins.

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              Glucose Sensing for Diabetes Monitoring: Recent Developments

              This review highlights recent advances towards non-invasive and continuous glucose monitoring devices, with a particular focus placed on monitoring glucose concentrations in alternative physiological fluids to blood.
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                Author and article information

                Journal
                Sensors (Basel)
                Sensors (Basel)
                sensors
                Sensors (Basel, Switzerland)
                MDPI
                1424-8220
                04 April 2018
                April 2018
                : 18
                : 4
                : 1084
                Affiliations
                Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; manasreh@ 123456uark.edu
                Author notes
                [* ]Correspondence: email: sm009@ 123456uark.edu ; Tel.: +1-479-595-1787
                Article
                sensors-18-01084
                10.3390/s18041084
                5948830
                29617292
                df16bcc0-16ba-40ee-b590-ef3824cb8e54
                © 2018 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

                History
                : 15 March 2018
                : 03 April 2018
                Categories
                Article

                Biomedical engineering
                optical sensor,glycated hemoglobin (hba1c),absorbance spectroscopy,beer’s law,diabetes

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