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Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 21272

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Special Issue Editor

Prof. Dr. P. Ravi Selvaganapathy

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Guest Editor

Department of Mechanical Engineering and McMaster School of Biomedical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
Interests: micro/nanofabrication; bioprinting; biomedical microdevices; microelectromechanical systems; microfluidics; medical and environmental sensors; smart textiles; biomaterials; artificial organs
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Special Issue Information

Dear Colleagues,

Microfluidics has been used to create a variety of platform technologies that have broad applications in the fields of environmental monitoring and medical diagnostics. These platforms miniaturize and automate the sample preparation to convert raw samples such as water, blood, urine, saliva, and sweat to a form that is conducive to reliable measurements using sensors. A variety of microfabrication processes, substrate materials, transduction methods, and integration techniques have been used to build a wide variety of microfluidic components and systems for this purpose. Several transduction methods including colorimetric, optical, electrochemical, chemiresistive, and electronic, in addition to other novel schemes, have been used for sensing.

In this Special Issue, we seek a collection of articles that describe the latest developments in this field, highlight key issues or challenges, and showcase recent work and emerging trends. These include review articles that synthesize and organize the research and development in these application areas as well as original research papers that present novel design concepts, fabrication methods, or new areas of application of microfluidic technology in environmental monitoring or medical diagnostics.

Prof. P. Ravi Selvaganapathy
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

sensing technologies and platforms
sample preparation
fabrication technologies and platforms
system integration
microfluidic components
microfabrication techniques
additive manufacturing of sensors

Published Papers (5 papers)

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Research

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17 pages, 2947 KiB

Open AccessArticle

Fluorescence Sensing Platforms for Epinephrine Detection Based on Low Temperature Cofired Ceramics

by Sylwia Baluta, Karol Malecha, Agnieszka Świst and Joanna Cabaj

Sensors 2020, 20(5), 1429; https://0-doi-org.brum.beds.ac.uk/10.3390/s20051429 - 05 Mar 2020

Cited by 15 | Viewed by 3608

Abstract

A novel fluorescence-sensing pathway for epinephrine (EP) detection was investigated. The ceramic-based miniature biosensor was developed through the immobilization of an enzyme (laccase, tyrosinase) on a polymer—poly-(2,6-di([2,2′-bithiophen]-5-yl)-4-(5-hexylthiophen-2-yl)pyridine), based on low temperature cofired ceramics technology (LTCC). The detection procedure was based on the oxidation of the substrate, i.e., in the presence of the enzyme. An alternative enzyme-free system utilized the formation of a colorful complex between Fe²⁺ ions and epinephrine molecules. With the optimized conditions, the analytical performance illustrated high sensitivity and selectivity in a broad linear range with a detection limit of 0.14–2.10 nM. Moreover, the strategy was successfully used for an EP injection test with labeled pharmacological samples. Full article

(This article belongs to the Special Issue Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics)

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11 pages, 5661 KiB

Open AccessArticle

Electroplating of Multiple Materials in Parallel Using Patterned Gels with Applications in Electrochemical Sensing

by Aliakbar Mohammadzadeh, Alison Fox-Robichaud and P. Ravi Selvaganapathy

Sensors 2020, 20(3), 886; https://0-doi-org.brum.beds.ac.uk/10.3390/s20030886 - 07 Feb 2020

Cited by 4 | Viewed by 4024

Abstract

Electrodeposition is a versatile technique for the fabrication of electrodes in micro-electroanalytical devices. Conductive but low-cost materials, such as copper, can be coated with functional yet higher-cost materials such as gold or silver using electrodeposition to lower the overall cost while maintaining functionality. When the electrodeposition of multiple materials is required, current methods use a multistep process that deposits one material at a time, which requires a significant amount of time and a significant number of steps. Additionally, they use a large volume of electrolytes suitable for coating large objects, which is wasteful and unnecessary for the prototyping or coating of microelectrodes with a small area. In this paper, a new method of electroplating is introduced in which we used gels to immobilize and pattern electroplating electrolytes on a substrate surface. Agarose, as an immobilizing medium, enables the immersion of the substrate in a common working electrolyte without cross-mixing different electrolytes. We demonstrate the printing of jelly electrolytes by using spot-dispensing or microfluidic flow. Xurographically patterned films laminated on the substrate function as a mask and confine the printed gels to desired locations. After printing, the substrate is placed in a common working electrolyte container, and multimaterial patterns are produced through the application of an electrical current in a single step. Full article

(This article belongs to the Special Issue Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics)

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10 pages, 2958 KiB

Open AccessArticle

A Systematic Study on Transit Time and Its Impact on Accuracy of Concentration Measured by Microfluidic Devices

by Yushan Zhang, Tianyi Guo and Changqing Xu

Sensors 2020, 20(1), 14; https://0-doi-org.brum.beds.ac.uk/10.3390/s20010014 - 18 Dec 2019

Cited by 7 | Viewed by 1931

Abstract

Gating or threshold selection is very important in analyzing data from a microflow cytometer, which is especially critical in analyzing weak signals from particles/cells with small sizes. It has been reported that using the amplitude gating alone may result in false positive events in analyzing data with a poor signal-to-noise ratio. Transit time (τ) can be set as a gating threshold along with side-scattered light or fluorescent light signals in the detection of particles/cells using a microflow cytometer. In this study, transit time of microspheres was studied systematically when the microspheres passed through a laser beam in a microflow cytometer and side-scattered light was detected. A clear linear relationship between the inverse of the average transit time and total flow rate was found. Transit time was used as another gate (other than the amplitude of side-scattering signals) to distinguish real scattering signals from noise. It was shown that the relative difference of the measured microsphere concentration can be reduced significantly from the range of 3.43%–8.77% to the range of 8.42%–111.76% by employing both amplitude and transit time as gates in analysis of collected scattering data. By using optimized transit time and amplitude gate thresholds, a good correlation with the traditional hemocytometer-based particle counting was achieved (R² > 0.94). The obtained results suggest that the transit time could be used as another gate together with the amplitude gate to improve measurement accuracy of particle/cell concentration for microfluidic devices. Full article

(This article belongs to the Special Issue Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics)

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13 pages, 5086 KiB

Open AccessArticle

Novel Platform for Droplet Detection and Size Measurement Using Microstrip Transmission Lines

by Juliana de Novais Schianti, Ariana L.C. Serrano, Daniel Orquiza de Carvalho, Rafael A. Penchel, Julio Mota Pinheiro, Mario R. Gongora-Rubio and Gustavo Pamplona Rehder

Sensors 2019, 19(23), 5216; https://0-doi-org.brum.beds.ac.uk/10.3390/s19235216 - 28 Nov 2019

Cited by 7 | Viewed by 3554

Abstract

We propose a novel platform for detecting as well as measuring the size of individual droplets in microfluidic channels using microstrip transmission lines. The most outstanding feature of our platform is that, as opposed to previous related works, its design allows for the droplet to flow in a microfluidic channel fabricated between the top strip and the ground plane of a microstrip transmission line. This provides enhanced interaction of the electromagnetic field with the detected droplets. The proposed design allows us to measure droplet size directly from the phase of the microwave signal, without the need for a resonator. The platform is based on low temperature co-fired ceramic (LTCC), which makes it more compatible with Radiofrequency (RF) and microwave technology than platforms used in previous works. With this platform, we are able to measure droplets as small as 150 µm in radius. It is worth pointing out that our device could also be used for detection, counting and measurement of other microscopic objects. Full article

(This article belongs to the Special Issue Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics)

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Review

Jump to: Research

44 pages, 3981 KiB

Open AccessReview

Metal Cation Detection in Drinking Water

by Johnson Dalmieda and Peter Kruse

Sensors 2019, 19(23), 5134; https://0-doi-org.brum.beds.ac.uk/10.3390/s19235134 - 23 Nov 2019

Cited by 56 | Viewed by 7639

Abstract

Maintaining a clean water supply is of utmost importance for human civilization. Human activities are putting an increasing strain on Earth’s freshwater reserves and on the quality of available water on Earth. To ensure cleanliness and potability of water, sensors are required to monitor various water quality parameters in surface, ground, drinking, process, and waste water. One set of parameters with high importance is the presence of cations. Some cations can play a beneficial role in human biology, and others have detrimental effects. In this review, various lab-based and field-based methods of cation detection are discussed, and the uses of these methods for the monitoring of water are investigated for their selectivity and sensitivity. The cations chosen were barium, cadmium, chromium, copper, hardness (calcium, magnesium), lead, mercury, nickel, silver, uranium, and zinc. The methods investigated range from optical (absorbance/fluorescence) to electrical (potentiometry, voltammetry, chemiresistivity), mechanical (quartz crystal microbalance), and spectrometric (mass spectrometry). Emphasis is placed on recent developments in mobile sensing technologies, including for integration into microfluidics. Full article

(This article belongs to the Special Issue Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics)

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