116 research outputs found
Fibre-based microfluidics for point-of-care diagnostic applications
No full textThis research project focuses on the development of fibre-based microfluidic devices for point-of-care (POC) detection in developing countries. Since paper and textile (the two most common fibre-based materials) have great potential for diagnostic applications, it has been of interest to researchers to combine traditional paper/textile strip tests with microfluidic devices to make them more sensitive, specific and user-friendly, while keeping them low-cost. These devices were originally designed for colorimetric detection. However, their sensitivity and functionality are not comparable with conventional laboratory tests and concentrated effort is required to improve them. This is the aim of this study. This thesis makes four original contributions to the functionality of recently- developed fibre-based microfluidic devices for use in real-world applications. The initial work presented in this thesis aims to enhance the sensitivity of the colorimetric detection methods currently in use with paper/textile strip tests by developing an alternative method of measuring the length of stained segments rather than their colour intensity. The length measurement method allows users to interpret results using a ruler, independent of image processing software. The following study considers the newly-developed fibre-based blood typing sensors. Although these sensors have shown promising performance for normal ABO blood types, correct typing of ABO sub-groups, which have a weak haemagglutination reaction with blood typing antibodies, is difficult to achieve. This is because the red blood cell (RBC) transport mechanism in fibre is not fully understood. This section focuses on understanding the underlying principles and the effects of fibre properties in blood typing sensors, and the results will enable sensor designers to further optimize low-cost blood typing sensors for detecting all types of blood. The subsequent section demonstrates an extremely simple and low-cost method for separating blood plasma from samples of whole human blood on paper-based sensors. Blood is the main body fluid which correlates with the condition of the body and is commonly used for biomedical diagnostics. However, due to the strong red colour, it is not suited for colorimetric detection and the plasma needs to be separated from RBCs before bio-diagnostics. Therefore, strategies to separate plasma from RBCs can enhance the functionality of paper-based sensors. This section focuses on integrating the blood plasma separation and colorimetric detection into a single device. This method paves the way for widespread biomedical tests using whole blood samples on paper-based microfluidic devices. The final part explores the ability of fibre to transport nutrients to cells in vitro. Although a three-dimensional (3D) cell culture in vitro is used to simulate the actual physiological environment, it relies on stacking individual layers and providing sufficient nutrients for cell growth. This study proposes the use of hydrophilic thread to support a multilayer cell culture system developed by stacking layers of scaffold. With the help of the thread, the cells are able to proliferate over a period of time. By expanding low-cost methods for further development of fibre-based microfluidics, this work gives researchers/sensor designers the ability to design more functional sensors for use in resource- limited regions
Detection of antibiotic residues in pork using paper-based microfluidic device coupled with filtration and concentration
No full text© 2018 Elsevier B.V. This work demonstrates a sensitive and rapid method for the detection of antibiotic residues in food samples by employing the filtration behaviour of paper combined with aggregation and precipitation of chemical reagents. Using this concept, we successfully determined the presence of oxytetracycline and norfloxacin residues in pork using metal complexation on microfluidic paper-based analytical devices (μPADs). The base substrate (top layer of the device) was fabricated by printing letter channels of the words “oxytetracycline” and “norfloxacin” before functionalization with copper (II) sulfate pentahydrate in 0.5 M sodium hydroxide and iron (III) nitrate nanohydrate in 5 mM ammonia solution for the detection of oxytetracycline and norfloxacin separately. A transition metal hydroxide formed upon reaction that created solid precipitates on paper and allowed antibiotic residues to bind to the metal ions via coordination chemistry. The metal ion-antibiotic complex could form on the filter paper and generated a visible color change with the detection limit of 1 ppm for both oxytetracycline and norfloxacin in pork. This procedure of filtration and concentration in combination with a simple text-reporting approach allows the end users to achieve a low limit of detection as well as easy result interpretation in food safety monitoring
Advances of Paper-Based Microfluidics for Diagnostics—The Original Motivation and Current Status
No full textPaper has shown potential as a ubiquitous material for fabricating micro analytical devices for diagnostic and drinking water screening applications for resource-limited regions; paper-based sensing technology has become a hot research field since 2007. Intensive research in the past decade has accumulated a large number of scientific publications. However, commercialization of microfluidic paper-based analytical devices (μPADs) for real applications is noticeably lagging behind. The "ASSURED" criteria (i.e., Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free, Deliver to the users who need them), set by the World Health Organization, specified the whole spectrum of requirements for a low-cost sensor designed for use in developing countries; they define the technical capabilities (i.e., "ASSR") and user acceptance (i.e., "UED") of low-cost sensing technology. While ASSR should be taken as the basic requirements of any sensor, UED determines whether or not the sensor could potentially be commercialized and gain user acceptance. This Perspective presents these two critical aspects of paper-based diagnostics by revisiting the original motivation of the paper-based analytical platform. It is our opinion that UED are important requirements that deserve more research to increase the commercialization of paper-based analytical devices
Colorimetric-based Sensing in Food Safety and Quality Analysis
No full textColorimetric-based Sensing in Food Safety and Quality Analysi
Simultaneous multiple assays on microfluidic cloth-based analytical devices
No full textThis paper describes a new class of point-of-care (POC) diagnostic devices for quantifying multiple assays by fabricating microfluidic devices on cotton cloth. This kind of microfluidic systems is appropriate for colorimetric assays that are low-cost, portable and simple to fabricate and to operate. Hydrophilic channels with hydrophobic barriers can be created using wax-resist patterning technique on cotton cloth fabric inspired from traditional batik technique. Using capillary force, the porosity of woven fabric and threads can wick micro volumes of aqueous samples from sample inlet into reaction zones across the hydrophilic channels for the mixing of their contents. These devices can be designed to perform single and multiple colorimetric assays of body fluids. The result can be observed by unaided human eye or by using digital camera and image analysis software. © 2011 IEEE
Colorimetric-based Sensing in Food Safety and Quality Analysis
No full textThe screening of biological contaminants, chemical hazards and allergens in food products is critical to understanding the potential negative effects on human health. Intensive research has been conducted to develop various detection methods to monitor food safety and quality. However, most of these developed methods are costly and require supporting equipment and professional skills to perform the testing. Therefore, there is high demand to develop alternative and innovative methods that are affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to fulfil the “ASSURED” criteria set by the World Health Organization (WHO). Colorimetric analysis can identify and determine the content of chemical elements/compounds in sample solutions by using various color reagents. This method has been used to detect and quantify specific pathogens, chemicals and hazards in foods for safety and quality control, which are suitable for use in laboratories and field studies. This chapter summarizes the recent advances in colorimetric analysis for assessing food safety and quality assurance, such as colorimetric detection of pathogens, toxins, parasites, antibiotic residues and chemical hazards in agri-food products. This chapter also conveys the current technical limitations and strategic research of colorimetric analysis required to further improve the performance of analytical assays in sensing food safety and quality control.</jats:p
Exploration of microfluidic devices based on multi-filament threads and textiles: A review
No full textExploration of microfluidic devices based on multi-filament threads and textiles: A revie
Exploration of microfluidic devices based on multi-filament threads and textiles: A review
No full textIn this paper, we review the recent progress in the development of low-cost microfluidic devices based on multifilament threads and textiles for semi-quantitative diagnostic and environmental assays. Hydrophilic multifilament threads are capable of transporting aqueous and non-aqueous fluids via capillary action and possess desirable properties for building fluid transport pathways in microfluidic devices. Thread can be sewn onto various support materials to form fluid transport channels without the need for the patterned hydrophobic barriers essential for paper-based microfluidic devices. Thread can also be used to manufacture fabrics which can be patterned to achieve suitable hydrophilic-hydrophobic contrast, creating hydrophilic channels which allow the control of fluids flow. Furthermore, well established textile patterning methods and combination of hydrophilic and hydrophobic threads can be applied to fabricate low-cost microfluidic devices that meet the low-cost and low-volume requirements. In this paper, we review the current limitations and shortcomings of multifilament thread and textile-based microfluidics, and the research efforts to date on the development of fluid flow control concepts and fabrication methods. We also present a summary of different methods for modelling the fluid capillary flow in microfluidic thread and textile-based systems. Finally, we summarized the published works of thread surface treatment methods and the potential of combining multifilament thread with other materials to construct devices with greater functionality. We believe these will be important research focuses of thread- and textile-based microfluidics in future. © 2013 AIP Publishing LLC
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