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Microfluidic Platforms for Environmental Monitoring and Medical Diagnostics

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 24084

Special Issue Editor


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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

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Keywords

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

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Published Papers (5 papers)

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Research

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17 pages, 2947 KiB  
Article
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://doi.org/10.3390/s20051429 - 5 Mar 2020
Cited by 16 | Viewed by 4044
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 [...] Read more.
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
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11 pages, 5661 KiB  
Article
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://doi.org/10.3390/s20030886 - 7 Feb 2020
Cited by 5 | Viewed by 4662
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. [...] Read more.
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
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10 pages, 2958 KiB  
Article
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://doi.org/10.3390/s20010014 - 18 Dec 2019
Cited by 6 | Viewed by 2242
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 [...] Read more.
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
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13 pages, 5086 KiB  
Article
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://doi.org/10.3390/s19235216 - 28 Nov 2019
Cited by 8 | Viewed by 3981
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 [...] Read more.
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
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Review

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44 pages, 3981 KiB  
Review
Metal Cation Detection in Drinking Water
by Johnson Dalmieda and Peter Kruse
Sensors 2019, 19(23), 5134; https://doi.org/10.3390/s19235134 - 23 Nov 2019
Cited by 63 | Viewed by 8565
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 [...] Read more.
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
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