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Ruiz-García I, Escobedo P, Ramos-Lorente CE, Erenas MM, Capitán-Vallvey LF, Carvajal MA, Palma AJ, López-Ruiz N. Capacitive platform for real-time wireless monitoring of liquid wicking in a paper strip. LAB ON A CHIP 2023; 23:4092-4103. [PMID: 37615614 DOI: 10.1039/d3lc00368j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Understanding the phenomenon of liquid wicking in porous media is crucial for various applications, including the transportation of fluids in soils, the absorption of liquids in textiles and paper, and the development of new and efficient microfluidic paper-based analytical devices (μPADs). Hence, accurate and real-time monitoring of the liquid wicking process is essential to enable precise flow transport and control in microfluidic devices, thus enhancing their performance and usefulness. However, most existing flow monitoring strategies require external instrumentation, are generally bulky and unsuitable for portable systems. In this work, we present a portable, compact, and cost-effective electronic platform for real-time and wireless flow monitoring of liquid wicking in paper strips. The developed microcontroller-based system enables flow and flow rate monitoring based on the capacitance measurement of a pair of electrodes patterned beneath the paper strip along the liquid path, with an accuracy of 4 fF and a full-scale range of 8 pF. Additionally to the wired transmission of the monitored data to a computer via USB, the liquid wicking process can be followed in real-time via Bluetooth using a custom-developed smartphone application. The performance of the capacitive monitoring platform was evaluated for different aqueous solutions (purified water and 1 M NaCl solution), various paper strip geometries, and several custom-made chemical valves for flow retention (chitosan-, wax-, and sucrose-based barriers). The experimental validation delivered a full-scale relative error of 0.25%, resulting in an absolute capacitance error of ±10 fF. In terms of reproducibility, the maximum uncertainty was below 10 nl s-1 for flow rate determination in this study. Furthermore, the experimental data was compared and validated with numerical analysis through electrical and flow dynamics simulations in porous media, providing crucial information on the wicking process, its physical parameters, and liquid flow dynamics.
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Affiliation(s)
- Isidoro Ruiz-García
- Electronic and Chemical Sensing Solutions (ECsens), CITIC-UGR, Department of Electronics and Computer Technology, University of Granada (UGR), 18071 Granada, Spain.
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Sport and Health University Research Institute (iMUDS), University of Granada (UGR), 18071 Granada, Spain
| | - Pablo Escobedo
- Electronic and Chemical Sensing Solutions (ECsens), CITIC-UGR, Department of Electronics and Computer Technology, University of Granada (UGR), 18071 Granada, Spain.
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Sport and Health University Research Institute (iMUDS), University of Granada (UGR), 18071 Granada, Spain
| | - Celia E Ramos-Lorente
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Electronic and Chemical Sensing Solutions (ECsens), Department of Analytical Chemistry, University of Granada (UGR), 18071 Granada, Spain
| | - Miguel M Erenas
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Electronic and Chemical Sensing Solutions (ECsens), Department of Analytical Chemistry, University of Granada (UGR), 18071 Granada, Spain
| | - Luis F Capitán-Vallvey
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Electronic and Chemical Sensing Solutions (ECsens), Department of Analytical Chemistry, University of Granada (UGR), 18071 Granada, Spain
| | - Miguel A Carvajal
- Electronic and Chemical Sensing Solutions (ECsens), CITIC-UGR, Department of Electronics and Computer Technology, University of Granada (UGR), 18071 Granada, Spain.
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Sport and Health University Research Institute (iMUDS), University of Granada (UGR), 18071 Granada, Spain
| | - Alberto J Palma
- Electronic and Chemical Sensing Solutions (ECsens), CITIC-UGR, Department of Electronics and Computer Technology, University of Granada (UGR), 18071 Granada, Spain.
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Sport and Health University Research Institute (iMUDS), University of Granada (UGR), 18071 Granada, Spain
| | - Nuria López-Ruiz
- Electronic and Chemical Sensing Solutions (ECsens), CITIC-UGR, Department of Electronics and Computer Technology, University of Granada (UGR), 18071 Granada, Spain.
- Unit of Excellence in Chemistry Applied to Biomedicine and the Environment of the University of Granada, Granada, Spain
- Sport and Health University Research Institute (iMUDS), University of Granada (UGR), 18071 Granada, Spain
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Costanzo A, Augello E, Battistini G, Benassi F, Masotti D, Paolini G. Microwave Devices for Wearable Sensors and IoT. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094356. [PMID: 37177569 PMCID: PMC10181738 DOI: 10.3390/s23094356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/21/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023]
Abstract
The Internet of Things (IoT) paradigm is currently highly demanded in multiple scenarios and in particular plays an important role in solving medical-related challenges. RF and microwave technologies, coupled with wireless energy transfer, are interesting candidates because of their inherent contactless spectrometric capabilities and for the wireless transmission of sensing data. This article reviews some recent achievements in the field of wearable sensors, highlighting the benefits that these solutions introduce in operative contexts, such as indoor localization and microwave sensing. Wireless power transfer is an essential requirement to be fulfilled to allow these sensors to be not only wearable but also compact and lightweight while avoiding bulky batteries. Flexible materials and 3D printing polymers, as well as daily garments, are widely exploited within the presented solutions, allowing comfort and wearability without renouncing the robustness and reliability of the built-in wearable sensor.
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Affiliation(s)
- Alessandra Costanzo
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
| | - Elisa Augello
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
| | - Giulia Battistini
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
| | - Francesca Benassi
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
| | - Diego Masotti
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
| | - Giacomo Paolini
- Department of Electrical, Electronic, and Information Engineering (DEI) "G. Marconi", Alma Mater Studiorum-University of Bologna, 40136 Bologna, Italy
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Hashimoto K, Ben Ishai P, Bründermann E, Tripathi SR. Dielectric property measurement of human sweat using attenuated total reflection terahertz time domain spectroscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:4572-4582. [PMID: 36187269 PMCID: PMC9484438 DOI: 10.1364/boe.467450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/18/2022] [Accepted: 07/18/2022] [Indexed: 06/16/2023]
Abstract
Sweat is one of the essential biofluids produced by the human body, and it contains various physiological biomarkers. These biomarkers can indicate human health conditions such as disease and illness. In particular, imbalances in the concentration of electrolytes can indicate the onset of disease. These same imbalances affect the dielectric properties of sweat. In this study, we used attenuated total reflection terahertz time domain spectroscopy to obtain the frequency-dependent dielectric properties of human sweat in a frequency range from 200 GHz to 2.5 THz. We have investigated the variation of dielectric properties of sweat collected from different regions of the human body, and we have observed that the real and imaginary part of dielectric permittivity decreases with the increase in frequency. A combination of left-hand Jonscher and Havriliak-Negami processes is used to model the results and reveal the presence of relaxation processes related to sodium and calcium ions concentrations. This information may help design novel biosensors to understand the human health condition and provide a hydration assessment.
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Affiliation(s)
- Kazuma Hashimoto
- Department of Mechanical Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan
| | - Paul Ben Ishai
- Department of Physics, Ariel University, P.O.B. 3, Ariel 40700, Israel
| | - Erik Bründermann
- Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan
- Institute for Beam Physics and Technology, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Saroj R. Tripathi
- Department of Mechanical Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan
- Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8561, Japan
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Rangaiah PKB, Mandal B, Avetisyan E, Chezhian AS, Augustine B, Perez MD, Augustine R. Preliminary Analysis of Burn Degree Using Non-invasive Microwave Spiral Resonator Sensor for Clinical Applications. FRONTIERS IN MEDICAL TECHNOLOGY 2022; 4:859498. [PMID: 35479303 PMCID: PMC9037089 DOI: 10.3389/fmedt.2022.859498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 03/07/2022] [Indexed: 12/02/2022] Open
Abstract
The European “Senseburn” project aims to develop a smart, portable, non-invasive microwave early effective diagnostic tool to assess the depth(d) and degree of burn. The objective of the work is to design and develop a convenient non-invasive microwave sensor for the analysis of the burn degree on burnt human skin. The flexible and biocompatible microwave sensor is developed using a magnetically coupled loop probe with a spiral resonator (SR). The sensor is realized with precise knowledge of the lumped element characteristics (resistor (R), an inductor (L), and a capacitor (C) RLC parameters). The estimated electrical equivalent circuit technique relies on a rigorous method enabling a comprehensive characterization of the sensor (loop probe and SR). The microwave resonator sensor with high quality factor (Q) is simulated using a CST studio suite, AWR microwave office, and fabricated on the RO 3003 substrate with a standard thickness of 0.13 mm. The sensor is prepared based on the change in dielectric property variation in the burnt skin. The sensor can detect a range of permittivity variations (εr 3–38). The sensor is showing a good response in changing resonance frequency between 1.5 and 1.71 GHz for (εr 3 to 38). The sensor is encapsulated with PDMS for the biocompatible property. The dimension of the sensor element is length (L) = 39 mm, width (W) = 34 mm, and thickness (T) = 1.4 mm. The software algorithm is prepared to automate the process of burn analysis. The proposed electromagnetic (EM) resonator based sensor provides a non-invasive technique to assess burn degree by monitoring the changes in resonance frequency. Most of the results are based on numerical simulation. We propose the unique circuit set up and the sensor device based on the information generated from the simulation in this article. The clinical validation of the sensor will be in our future work, where we will understand closely the practical functioning of the sensor based on burn degrees. The senseburn system is designed to support doctors to gather vital info of the injuries wirelessly and hence provide efficient treatment for burn victims, thus saving lives.
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Affiliation(s)
- Pramod K. B. Rangaiah
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
| | - Bappaditya Mandal
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
| | - Erik Avetisyan
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
| | - Arvind Selvan Chezhian
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
| | - Bobins Augustine
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
- Ångström Laboratory, Division of Computer Systems, Department of Information Technology, Uppsala Networked Objects (UNO), Uppsala University, Uppsala, Sweden
| | - Mauricio David Perez
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
| | - Robin Augustine
- Ångström Laboratory, Department of Engineering Sciences, Microwaves in Medical Engineering Group, Solid State Electronics, Uppsala University, Uppsala, Sweden
- *Correspondence: Robin Augustine
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Design and Evaluation of a Button Sensor Antenna for On-Body Monitoring Activity in Healthcare Applications. MICROMACHINES 2022; 13:mi13030475. [PMID: 35334779 PMCID: PMC8955430 DOI: 10.3390/mi13030475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 03/13/2022] [Accepted: 03/15/2022] [Indexed: 02/05/2023]
Abstract
A button sensor antenna for on-body monitoring in wireless body area network (WBAN) systems is presented. Due to the close coupling between the sensor antenna and the human body, it is highly challenging to design sensor antenna devices. In this paper, a mechanically robust system is proposed that integrates a dual-band button antenna with a wireless sensor module designed on a printed circuit board (PCB). The system features a small footprint and has good radiation characteristics and efficiency. This was fabricated, and the measured and simulated results are in good agreement. The design offers a wide range of omnidirectional radiation patterns in free space, with a reflection coefficient (S11) of −29.30 (−30.97) dB, a maximum gain of 1.75 (5.65) dBi, and radiation efficiency of 71.91 (92.51)% in the lower and upper bands, respectively. S11 reaches −23.07 (−27.07) dB and −30.76 (−31.12) dB, respectively, with a gain of 2.09 (6.70) dBi and 2.16 (5.67) dBi, and radiation efficiency of 65.12 (81.63)% and 75.00 (85.00)%, when located on the body for the lower and upper bands, respectively. The performance is minimally affected by bending, movement, and fabrication tolerances. The specific absorption rate (SAR) values are below the regulatory limitations for the spatial average over 1 g (1.6 W/Kg) and 10 g of tissues (2.0 W/Kg). For both indoor and outdoor conditions, experimental results of the range tests confirm the coverage of up to 40 m.
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El-Naggar ME, Abu Ali OA, Saleh DI, Abu-Saied MA, Khattab TA. Preparation of green and sustainable colorimetric cotton assay using natural anthocyanins for sweat sensing. Int J Biol Macromol 2021; 190:894-903. [PMID: 34534584 DOI: 10.1016/j.ijbiomac.2021.09.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/25/2021] [Accepted: 09/09/2021] [Indexed: 12/20/2022]
Abstract
Herein, we develop a novel smart cotton swab as a diagnostic assay for onsite monitoring of sweat pH changes toward potential applications in monitoring human healthcare and drug exam. Anthocyanin (Ac) can be extracted from Brassica oleracea var. capitata f. rubra using a simple procedure. Then, it can be used as a direct dye into cotton fibers using potash alum as mordant (M) to fix the anthocyanin dye onto the surface of the cotton fabric (Cot). This was monitored by generating mordant/anthocyanin nanoparticles (MAcNPs) onto the fabric surface. The cotton sensor assay demonstrated colorimetric changes in the ultraviolet-visible absorbance spectral analysis associated with a blueshift from 588 to 422 nm with increasing the pH of a perspiration simulant fluid. The biochromic performance of the dyed cotton diagnostic assay depended essentially on the halochromic activity of the anthocyanin spectroscopic probe to demonstrate a color change from pink to green due to intramolecular charge transfer occurring on the anthocyanin chromophore. After dyeing, no significant defects were detected in air-permeability and bend length. High colorfastness was investigated for the dyed cotton fabrics.
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Affiliation(s)
- Mehrez E El-Naggar
- Textile Research Division, National Research Center (Affiliation ID: 60014618), Dokki, Cairo, Egypt.
| | - Ola A Abu Ali
- Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Dalia I Saleh
- Department of Chemistry, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - M A Abu-Saied
- Polymeric Materials Research Department, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technological Applications (SRTA-CITY), New Borg El-Arab City, 21934, Alexandria, Egypt
| | - Tawfik A Khattab
- Textile Research Division, National Research Center (Affiliation ID: 60014618), Dokki, Cairo, Egypt
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Bouchalkha A, Karli R, Alhammadi K. Reusable Sensor for Strontium Sulfate Scale Monitoring in Seawater. MATERIALS (BASEL, SWITZERLAND) 2021; 14:676. [PMID: 33535671 PMCID: PMC7867127 DOI: 10.3390/ma14030676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 11/19/2022]
Abstract
The onset of scaling in oil pipelines can halt or drastically reduce oil production, causing huge financial losses and delays. Current methods used to monitor scaling can take weeks, while the scaling process only takes few hours. The proposed sensor is designed for online monitoring of strontium ions concentration in seawater as an early scaling indicator. The sensor operates in the GHz range by probing the shift in the resonance frequency due to changes in the ionic concentrations of the medium. The results show selective sensitivity to changes in the strontium ions concentration even in the presence of many other ions found in seawater. The measured sensitivity is found to be stable and linear with a detection level of better than 0.08% (0.042 mol/L) of strontium ions in seawater. This work demonstrates a robust GHz sensor for strontium sulfate scale monitoring and early detection, which could be used in the oil industry to prevent huge production losses. These results could also be extended further to target the monitoring of other ions in different industrial sectors.
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Affiliation(s)
- Abdellatif Bouchalkha
- Directed Energy Research Centre, Technology Innovation Institute, Abu Dhabi 9639, United Arab Emirates
| | - Radouane Karli
- Electrical Engineering Department, Ecole Mohammedia des Ingenieurs (EMI), Mohammed V University-Agdal, Rabat 10090, Morocco;
| | - Khalid Alhammadi
- Electrical and Computer Engineering Department, Khalifa University, Abu Dhabi 127788, United Arab Emirates;
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Pandey PC, Pandey G, Narayan RJ. Minimally Invasive Platforms in Biosensing. Front Bioeng Biotechnol 2020; 8:894. [PMID: 32984266 PMCID: PMC7487318 DOI: 10.3389/fbioe.2020.00894] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 07/13/2020] [Indexed: 02/05/2023] Open
Abstract
The interaction of sensing components with body fluids is a basic requirement for clinical diagnostics; a variety of novel platforms have recently been developed for invasive and non-invasive sensing. In this manuscript, recent advancements related to minimally invasive platform for biosensing are reviewed. Many approaches have been utilized for generating minimally invasive platforms that require a small volume of body fluid; for example, the use of small-scale needles known as microneedles for minimally invasive detection has been demonstrated. The use of capillary action in microneedle-assisted biosensing may facilitate the detection of analytes in body fluids. This review considers recent innovations in the structure and performance of minimally invasive sensos.
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Affiliation(s)
- Prem C Pandey
- Department of Chemistry, Indian Institute of Technology (BHU), Varanasi, India
| | - Govind Pandey
- Department of Pediatrics, King George Medical University, Lucknow, India
| | - Roger J Narayan
- Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC, United States
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El Gharbi M, Fernández-García R, Ahyoud S, Gil I. A Review of Flexible Wearable Antenna Sensors: Design, Fabrication Methods, and Applications. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E3781. [PMID: 32867144 PMCID: PMC7503853 DOI: 10.3390/ma13173781] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/18/2020] [Accepted: 08/24/2020] [Indexed: 11/16/2022]
Abstract
This review paper summarizes various approaches developed in the literature for antenna sensors with an emphasis on flexible solutions. The survey helps to recognize the limitations and advantages of this technology. Furthermore, it offers an overview of the main points for the development and design of flexible antenna sensors from the selection of the materials to the framing of the antenna including the different scenario applications. With regard to wearable antenna sensors deployment, a review of the textile materials that have been employed is also presented. Several examples related to human body applications of flexible antenna sensors such as the detection of NaCl and sugar solutions, blood and bodily variables such as temperature, strain, and finger postures are also presented. Future investigation directions and research challenges are proposed.
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Affiliation(s)
- Mariam El Gharbi
- Department of Electronic Engineering, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain; (M.E.G.); (R.F.-G.)
| | - Raúl Fernández-García
- Department of Electronic Engineering, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain; (M.E.G.); (R.F.-G.)
| | - Saida Ahyoud
- Information Technology & Systems Modeling Team, Faculty of Sciences, Abdelmalek Essaadi University, 93002 Tetouan, Morocco;
| | - Ignacio Gil
- Department of Electronic Engineering, Universitat Politècnica de Catalunya, 08222 Terrassa, Spain; (M.E.G.); (R.F.-G.)
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Study of the Dielectric Properties of Artificial Sweat Mixtures at Microwave Frequencies. BIOSENSORS-BASEL 2020; 10:bios10060062. [PMID: 32527001 PMCID: PMC7344616 DOI: 10.3390/bios10060062] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/05/2020] [Accepted: 06/05/2020] [Indexed: 02/05/2023]
Abstract
Analysis of sweat is of interest for a variety of diagnosis and monitoring applications in healthcare. In this work, detailed measurements of the dielectric properties of solutions representing the major components of sweat are presented. The measurements include aqueous solutions of sodium chloride (NaCl), potassium chloride (KCl), urea, and lactic acid, as well as their mixtures. Moreover, mixtures of NaCl, KCl, urea, and lactic acid, mimicking artificial sweat at different hydration states, are characterized, and the data are fitted to a Cole-Cole model. The complex dielectric permittivity for all prepared solutions and mixtures is studied in the range of 1-20 GHz, at temperature of 23 °C, with ionic concentrations in the range of 0.01-1.7 mol/L.
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Shokrekhodaei M, Quinones S. Review of Non-invasive Glucose Sensing Techniques: Optical, Electrical and Breath Acetone. SENSORS (BASEL, SWITZERLAND) 2020; 20:E1251. [PMID: 32106464 PMCID: PMC7085605 DOI: 10.3390/s20051251] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 02/22/2020] [Accepted: 02/23/2020] [Indexed: 12/12/2022]
Abstract
Annual deaths in the U.S. attributed to diabetes are expected to increase from 280,210 in 2015 to 385,840 in 2030. The increase in the number of people affected by diabetes has made it one of the major public health challenges around the world. Better management of diabetes has the potential to decrease yearly medical costs and deaths associated with the disease. Non-invasive methods are in high demand to take the place of the traditional finger prick method as they can facilitate continuous glucose monitoring. Research groups have been trying for decades to develop functional commercial non-invasive glucose measurement devices. The challenges associated with non-invasive glucose monitoring are the many factors that contribute to inaccurate readings. We identify and address the experimental and physiological challenges and provide recommendations to pave the way for a systematic pathway to a solution. We have reviewed and categorized non-invasive glucose measurement methods based on: (1) the intrinsic properties of glucose, (2) blood/tissue properties and (3) breath acetone analysis. This approach highlights potential critical commonalities among the challenges that act as barriers to future progress. The focus here is on the pertinent physiological aspects, remaining challenges, recent advancements and the sensors that have reached acceptable clinical accuracy.
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Affiliation(s)
- Maryamsadat Shokrekhodaei
- Department of Electrical and Computer Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Stella Quinones
- Department of Metallurgical, Materials and Biomedical Engineering, The University of Texas at El Paso, El Paso, TX 79968, USA;
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