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Timely and accurate molecular diagnostics at the point-of-care (POC) level is critical to global health. To this end, we propose a handheld convective-flow real-time polymerase chain reaction (PCR) system capable of direct sample-to-answer genetic analysis for the first time. Such a system mainly consists of a magnetic bead-assisted photothermolysis sample preparation, a closed-loop convective PCR reactor, and a wireless video camera-based real-time fluorescence detection. The sample preparation exploits the dual functionality of vancomycin-modified magnetic beads (VMBs) for bacteria enrichment and photothermal conversion, enabling cell pre-concentration and lysis to be finished in less than 3 min. On the presented system, convective thermocycling is driven by a single-heater thermal gradient, and its amplification is monitored in real-time, with an analysis speed of less than 25 min, a dynamic linear range from 10 6 to 10 1 copies/µL and a detection sensitivity of as little as 1 copies/µL. Additionally, the proposed PCR system is self-contained with a control electronics, pocket-size and battery-powered, providing a low-cost genetic analysis in a portable format. Therefore, we believe that this integrated system may become a potential candidate for fast, accurate and affordable POC molecular diagnostics. [ABSTRACT FROM AUTHOR]

As is known to all, pathogenic bacteria have a serious impact on human health. The development of sensitive, simple, rapid and low-cost bacterial detection method is necessary. Nowadays, some conventional methods (such as plate count, polymerase chain reaction (PCR) and immunological techniques) can not meet the above needs. This work was aimed at providing a new method for addressing these unmet needs. This study proposed a novel PCR-free and label-free DNA sensor based on multiple linear hybridization chain reaction (ML-HCR) and cloth-based closed bipolar electrochemiluminescence for sensitive and rapid detection of Escherichia coli (E. coli). The target DNA can be obtained from the E. coli genomic DNA by using the restriction enzyme instead of PCR. The auxiliary probe-triggered ML-HCR is carried out with continuous hybridization of two hairpin DNA, and as a result the double stranded DNA is formed to provide a large number of binding sites for Ru(bpy) 3 2+. The whole detection is PCR-free and label-free, and thus the detection procedure is easier and faster. Under optimized conditions, the linear detection range was from 102 to 107 CFU/mL, and the detection limit was low to 38 CFU/mL. In addition, the proposed DNA sensor has an acceptable selectivity, stability and reproducibility, and is successfully applied to detect E. coli in milk samples with the recoveries from 96.24% to 105.98%. The proposed DNA sensor has broad application prospects in the fields of bacterial detection and gene diagnose. Further, this method has potential to be extended for establishing miniaturized, integrated, and automated detection system. [Display omitted] • The PCR-free and label-free cloth-based DNA sensor is firstly proposed. • The multiple linear HCR protocol is firstly proposed to amplify the ECL signal. • The target DNA can be quickly obtained by the restriction endonuclease. • The Ru(byp) 3 2+ is select as label-free signal molecule. • The presented method can be applied for E. coli detection in complex samples. [ABSTRACT FROM AUTHOR]

In this work, a handheld paper-based bipolar electrode-electrochemiluminescence (P-BPE-ECL) system has been proposed. In this system, a rechargeable battery is used for power supply, while a smartphone is applied for read-out of ECL signal. For the P-BPE-ECL, the carbon ink-based BPE and driving electrodes are screen-printed on the paper, and the wax-screen-printing is employed to fabricate microfluidic channels on electrode-patterned paper. Moreover, the luminol/H 2 O 2 -based ECL reaction is applied to demonstrate the quantitative ability of the P-BPE-ECL system. Under optimized conditions, H 2 O 2 can be determined over the range of 5–5000 μM, with a detection limit of 1.75 μM, and relative standard deviations (RSDs) of 7.59%, 3.82% and 4.93% for 10, 100 and 1000 μM H 2 O 2 (n = 5). Thus, this system has an acceptable sensitivity, dynamic range, stability and reproducibility. Finally, the applicability of the P-BPE-ECL system is demonstrated for detection of glucose in phosphate buffer solution (PBS) and artificial urine (AU) samples, with the detection limits of 0.017 mM and 0.030 mM, respectively. Moreover, the P-BPE-ECL system has the ability to perform high-throughput detection of glucose. Therefore, the developed system can provide a new platform for many applications such as point-of-care testing, health diagnosis and environmental monitoring. [ABSTRACT FROM AUTHOR]

This paper describes the first demonstration of the combination of micropatterned paper devices (μPPDs) and polydiacetylene (PDA) colorimetric probes for double-stranded DNA (dsDNA) detection with high sensitivity and fast response. The device is rapidly fabricated on paper by wax-screen-printing. The amine-functionalized PDA vesicles are spotted to the paper chambers, followed by the introduction of the polymerase chain reaction (PCR)-amplified dsDNA targets. After the completion of the ionic interactions between the targets and the probes, a significantly different optical signal is produced, thereby facilitating the naked-eye detection. Additionally, the signals are readily documented through a smartphone for quantitative analysis. In this study, the PDA colorimetric assay in μPPDs is capable of discriminating the presence of the target down to 10 nM (the typical concentration of PCR amplicons is around 100 nM). At such concentration, the value of colorimetric response in paper is about 41% higher than that in tube, leading to an enhanced sensitivity. In addition, the colorimetric reaction in μPPDs is accomplished in 1 min, and the analytical speed is much faster than that observed in tube. These results show that the paper-based PDA colorimetry should have greatly enhanced applications as a technology for DNA diagnostics. [ABSTRACT FROM AUTHOR]

In this work, we report the first demonstration of chemiluminescence (CL) detection for microfluidic cloth-based analytical devices (μCADs). Wax screen-printing is used to make cloth channels or chambers, and enzyme-catalyzed CL reactions are imaged using an inexpensive charge coupled device (CCD). We first evaluate the relationship between the wicking rate and the length/width of cloth channel. For our device, the channel length and width between the loading and detection chambers are optimized to be 10 mm and 3 mm. Thus, the detection procedure can be accomplished in about 15 s on a cloth-based device (15×30 mm 2 ) by using 25-μL sample spotted on it. Next, several parameters affecting cloth-based CL intensity are studied, including exposure time, pH, and concentrations of luminol and enzyme. Under optimal conditions, a linear relationship is obtained between CL intensity and hydrogen peroxide (H 2 O 2 ) concentrations in the range of 0.5–5 mM with a detection limit of 0.46 mM. Finally, the utility of cloth-based CL is demonstrated for determination of H 2 O 2 residues in meat samples. On our device, the chicken meat soaked for 6 h with 3% H 2 O 2 can be detected. Moreover, the supernatant of grinded meat sample can be directly applied, without need for other treatments. We believe that μCADs with CL detection could provide a new platform of rapid and low-cost assays for use in areas such as food detection and environmental monitoring. [ABSTRACT FROM AUTHOR]

In this work, we first introduce the fabrication of microfluidic cloth-based analytical devices (μCADs) using a wax screen-printing approach that is suitable for simple, inexpensive, rapid, low-energy-consumption and high-throughput preparation of cloth-based analytical devices. We have carried out a detailed study on the wax screen-printing of μCADs and have obtained some interesting results. Firstly, an analytical model is established for the spreading of molten wax in cloth. Secondly, a new wax screen-printing process has been proposed for fabricating μCADs, where the melting of wax into the cloth is much faster (∼5 s) and the heating temperature is much lower (75 °C). Thirdly, the experimental results show that the patterning effects of the proposed wax screen-printing method depend to a certain extent on types of screens, wax melting temperatures and melting time. Under optimized conditions, the minimum printing width of hydrophobic wax barrier and hydrophilic channel is 100 μm and 1.9 mm, respectively. Importantly, the developed analytical model is also well validated by these experiments. Fourthly, the μCADs fabricated by the presented wax screen-printing method are used to perform a proof-of-concept assay of glucose or protein in artificial urine with rapid high-throughput detection taking place on a 48-chamber cloth-based device and being performed by a visual readout. Overall, the developed cloth-based wax screen-printing and arrayed μCADs should provide a new research direction in the development of advanced sensor arrays for detection of a series of analytes relevant to many diverse applications. [ABSTRACT FROM AUTHOR]

A novel paper-based open bipolar electrode-electrochemiluminescence (P- o -BPE-ECL) sensing has been developed for visual detection. Wax-screen-printing was employed to make microfluidic channels on filter paper, and the carbon ink-based BPE and driving electrodes were screen-printed on paper. An inexpensive CCD camera was used as a detector for imaging sensing. In this study, two P- o -BPE-ECL imaging sensing platforms were demonstrated. For the first one, a hydrophilic paper channel was used to host a single “band”-shaped BPE. Under optimal conditions, this P- o -BPE-ECL platform successfully fulfilled the imaging sensing of tri- n -propylamine (TPA) with a linear range from 10 to 1000 μM with a detection limit of 8.7 μM. In addition, the determination of H 2 O 2 using this platform could be performed in the linear range of 50 μM to 5000 μM with a detection limit of 46.6 μM. For the second platform, an open BPE array configuration has been proposed for P- o -BPE-ECL sensing, where eleven BPEs were stridden across the two legs of the “U”-shaped paper channel. On this prototype, a simple screening application has been performed. These results show that the proposed strategy offers great promise in providing a simple, low-cost, rapid and environment-friendly solution for biochemical applications. [ABSTRACT FROM AUTHOR]

A handheld flow genetic analysis system (FGAS) is proposed for rapid, sensitive, multiplex and real-time quantification of nucleic acids at the point-of-care (POC) level. The FGAS includes a helical thermal-gradient microreactor and a microflow actuator, as well as control circuitry for temperature, fluid and power management, and smartphone fluorescence imaging. All of these features are integrated into a field-portable and easy-to-use molecular diagnostic platform powered by lithium batteries. Due to the unique design of the microreactor, not only steady temperatures for denaturation and annealing/extension but also a linear thermal gradient for spatial high-resolution melting can be achieved through simply maintaining a single heater at constant temperature. The smartphone fluorescence imaging system has a wide field of view that captures all PCR channels of the microreactor in a single snapshot without the need for any mechanical scanning. By these designs, the FGAS enables real-time monitoring of the temporal and spatial fluorescence signatures of amplicons during continuous-flow amplification. On the current FGAS, visual detection of as little as 10 copies per μL of genomic DNA of Salmonella enterica was achieved in 15 min, with real-time quantitative detection of the DNA over 6 orders of magnitude concentration from 106 to 101 copies per μL also completed in 7.5–15 min. In addition, multiple pathogenic DNA targets could be simultaneously discriminated with direct bar-chart readout or multiplex spatial melting in serial flow. We anticipate that the FGAS has great potential to become a next-generation gene analyzer for POC molecular diagnostics. [ABSTRACT FROM AUTHOR]

This paper describes the development of a paper-based microfluidic device that detects long DNA amplicons on the basis of hybridization reactions with a covalently immobilized DNA probe and biotin-labeled signal DNA strands, and chemiluminescent (CL) reactions catalyzed by a horseradish peroxidase (HRP)-streptavidin conjugate. The paper-based microfluidic CL biosensor is developed for detection of 198-bp DNA fragments obtained by PCR amplification of the Listeria monocytogenes hlyA gene, where the CL intensity is detected by a simple, inexpensive CCD. To our knowledge, the combined use of the CCD sensing and paper-based microfluidic CL detection is first proposed here. The paper-based device includes wax-screen printed channels, and further explores origami-type folds to create an easy-to-operate valve that makes it possible to successively wash the detection zone in-between hybridization steps. Compared with other paper-based wax-screen-printing methods, the proposed method is faster and needs lower heating temperature. In our DNA biosensor, CL signals generated using a HRP-luminol-H2O2 system are heightened with p-iodine phenol (PIP) and detected with a CCD system. Under optical conditions, a linear range of 1.94 × 10 −1 pmol/L to 1.94 × 10 4 pmol/L is achieved and the limit of detection is found to be 6.3 × 10 −2 pmol/L. And, this detection limit is 3–5 orders of magnitude lower than those obtained from other CCD-based microfluidic CL DNA assays. The results show that the proposed integration of paper-based microfluidics, CL method and CCD sensing offers great promises in providing a highly-sensitive, reliable and cost-effective solution for gene biosensing applications. [ABSTRACT FROM AUTHOR]

In this work, we first report a facile, low-cost and high-throughput method for photolithographical fabrication of microfluidic cloth-based analytical devices (μCADs) by simply using a cotton cloth as a substrate material and employing an inexpensive hydrophobic photoresist laboratory-formulated from commercially available reagents, which allows patterning of reproducible hydrophilic–hydrophobic features in the cloth with well-defined and uniform boundaries. Firstly, we evaluated the wicking properties of cotton cloths by testing the wicking rate in the cloth channel, in combination with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. It is demonstrated that the wicking properties of the cloth microfluidic channel can be improved by soaking the cloth substrate in 20 wt% NaOH solution and by washing the cloth-based microfluidic patterns with 3 wt% SDS solution. Next, we studied the minimum dimensions achievable for the width of the hydrophobic barriers and hydrophilic channels. The results indicate that the smallest width for a desired hydrophobic barrier is designed to be 100 μm and that for a desired hydrophilic channel is designed to be 500 μm. Finally, the high-throughput μCADs prepared using the developed fabrication technique were demonstrated for colorimetric assays of glucose and protein in artificial urine samples. It has been shown that the photolithographically patterned μCADs have potential for a simple, quantitative colorimetric urine test. The combination of cheap cloth and inexpensive high-throughput photolithography enables the development of new types of low-cost cloth-based microfluidic devices, such as “microzone plates” and “gate arrays”, which provide new methods to perform biochemical assays or control fluid flow. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) detection is a widely used detection method that uses light to stimulate and photocurrent signals to detect the target. Due to the disengagement of the excitation unit and the detection unit, the PEC background signal is reduced, and the detection sensitivity is improved. In this work, we report the first demonstration of PEC detection for microfluidic cloth-based analytical devices (μCADs). Using PEC μCADs integrated with cadmium sulfide quantum dots (CdS QDs) and multiwalled carbon nanotubes (MWCNTs), the nonenzymatic, sensitive and rapid measurement of glucose in saliva has been achieved. For the cloth-based device, the PEC reaction zone and cloth-based electrodes can be fabricated by inexpensive wax-based and carbon ink-based screen-printing, respectively. By the layer-by-layer method, the as-prepared poly (dimethyl diadly ammonium chloride-functionalized) MWCNTs (PDDA-MWCNTs) and CdS QDs are successively adsorbed onto the working electrode surface of the cloth-based device. In the presence of an excitation source and glucose, the CdS QDs generate a strong oxidizing electron hole that can then continuously oxidize glucose to produce an electrical signal for glucose detection. Under optimized conditions, a linear dependence is obtained between the PEC signal and glucose concentrations in the range of 0.05–1000 μM with a detection limit of 15.99 nM. In the detection range, the cloth-based device also shows acceptable selectivity, reproducibility, and long-term stability. Moreover, the method has been implemented for the detection of glucose in real saliva samples, suggesting good potential for biochemical applications. [Display omitted] • The coupling of PEC detection and μCADs has been firstly proposed. • The μCADs are used for non-enzymatic glucose analysis for the first time. • The self-assembly of PDDA-MWCNTs and CdS QDs is firstly used for PEC detection. • The PEC μCADs have been used for detection of glucose in human saliva samples. • The method is highly sensitive (detection limit of 15.99 nM), simple, rapid, and low-cost. [ABSTRACT FROM AUTHOR]

Highlights: [•] A high-throughput and rapid microfluidic method for pathogen detection is proposed. [•] The method offers a simple and convenient way toward high-throughput DNA analysis. [•] Important parameters of segmented continuous-flow multiplex PCR were investigated. [•] The proposed method is suitable for high-throughput biomedical monitoring. [Copyright &y& Elsevier]

Abstract: Automatic 3D extraction of building roofs from remotely sensed data is important for many applications including city modelling. This paper proposes a new method for automatic 3D roof extraction through an effective integration of LIDAR (Light Detection And Ranging) data and multispectral orthoimagery. Using the ground height from a DEM (Digital Elevation Model), the raw LIDAR points are separated into two groups. The first group contains the ground points that are exploited to constitute a ‘ground mask’. The second group contains the non-ground points which are segmented using an innovative image line guided segmentation technique to extract the roof planes. The image lines are extracted from the grey-scale version of the orthoimage and then classified into several classes such as ‘ground’, ‘tree’, ‘roof edge’ and ‘roof ridge’ using the ground mask and colour and texture information from the orthoimagery. During segmentation of the non-ground LIDAR points, the lines from the latter two classes are used as baselines to locate the nearby LIDAR points of the neighbouring planes. For each plane a robust seed region is thereby defined using the nearby non-ground LIDAR points of a baseline and this region is iteratively grown to extract the complete roof plane. Finally, a newly proposed rule-based procedure is applied to remove planes constructed on trees. Experimental results show that the proposed method can successfully remove vegetation and so offers high extraction rates. [Copyright &y& Elsevier]

Road condition data are important in transportation management systems. Over the last decades, significant progress has been made and new approaches have been proposed for efficient collection of pavement condition data. However, the assessment of unpaved road conditions has been rarely addressed in transportation research. Unpaved roads constitute approximately 40% of the U.S. road network, and are the lifeline in rural areas. Thus, it is important for timely identification and rectification of deformation on such roads. This article introduces an innovative Unmanned Aerial Vehicle (UAV)-based digital imaging system focusing on efficient collection of surface condition data over rural roads. In contrast to other approaches, aerial assessment is proposed by exploring aerial imagery acquired from an unpiloted platform to derive a three-dimensional (3D) surface model over a road distress area for distress measurement. The system consists of a low-cost model helicopter equipped with a digital camera, a Global Positioning System (GPS) receiver and an Inertial Navigation System (INS), and a geomagnetic sensor. A set of image processing algorithms has been developed for precise orientation of the acquired images, and generation of 3D road surface models and orthoimages, which allows for accurate measurement of the size and the dimension of the road surface distresses. The developed system has been tested over several test sites with roads of various surface distresses. The experiments show that the system is capable for providing 3D information of surface distresses for road condition assessment. Experiment results demonstrate that the system is very promising and provides high accuracy and reliable results. Evaluation of the system using 2D and 3D models with known dimensions shows that subcentimeter measurement accuracy is readily achieved. The comparison of the derived 3D information with the onsite manual measurements of the road distresses reveals differences of 0.50 cm, demonstrating the potential of the presented system for future practice. [ABSTRACT FROM AUTHOR]

Abstract: The development of microfluidic tools for nucleic acid analysis has become a burgeoning area of research during the postgenome era. Here we have developed a microfluidic device that integrates reverse transcription (RT) and polymerase chain reaction (PCR) with online fluorescence detection to realize a rapid detection system for performing both genetic amplification and product analysis. The microfluidic device mainly comprises a grooved copper heating block for RT and a heated cylinder for amplification. To expedite the analysis process, we combined the continuous-flow PCR with an online fluorescence detection system that allows analysis of amplification products within 1min. Rotaviruses are worldwide enteric pathogens in humans and animals responsible for a significant burden of disease through person-to-person transmission and exposure to contaminated foods and water. In this study, rotavirus from stool specimens was successfully amplified and detected using the RT-PCR microfluidic system within 1h, and the limit of detection of the RNA concentration was estimated to be 3.6×104 copiesμl−1. Compared with a large-scale apparatus, the integrated microfluidic system presented here can perform rapid nucleic acid amplification and analysis, possibly making it a crucial platform for future diagnosis application. [Copyright &y& Elsevier]

n oscillatory-flow multiplex PCR method in a capillary microfluidic channel has been developed for the simultaneous determination of pre-purified DNA of multiple foodborne bacterial pathogens. The PCR solution passes three temperature zones in an oscillatory manner. The thermal stability and sample evaporation of the microfluidic device were investigated. Under controlled conditions, a highly efficient multiplex PCR was accomplished as demonstrated for the simultaneous amplifications of 278 bp, 168 bp, and 106 bp DNA fragments within 35 min after 35 cycles for simultaneous detection of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes. This is much shorter than that of a conventional PCR machine. The detection limits of bacterial genome DNA for the three species are about 399, 314, and 626 copies per μL, respectively. This is comparable to those obtained with the conventional multiplex PCR. Consequently, the oscillatory-flow multiplex PCR technology holds good potential for rapid amplification and detection of nucleic acids of microbial foodborne pathogens. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: We present a thermal gradient convective polymerase chain reaction (PCR) for parallel DNA amplification with different annealing temperatures. The thermal gradient for microfluidic gradient PCR is produced by an innovative fin design whose formation principle is given. Without the need for a pump, the buoyancy forces continuously circulate reagents in a closed loop through different thermal zones, which brings self-actuated convective-flow PCR. In our prototype, we measured a temperature difference of about 45°C along the gradient direction on the copper flake (45×40×4mm). When the temperature of the hot zone is 90–97°C and the temperature of the cold zone is 60–70°C, the convection triggered two-temperature amplification of 112-bp fragment of Escherichia coli DNA. The time for amplification is less than 45min. Interestingly, parallel DNA amplification with different annealing temperatures ranging from 60 to 70°C was performed by this method. The PCR thermocycler demonstrated herein can be further scaled down and the loop length can be further reduced, and therefore the PCR times can be further reduced. These devices are suited as a platform for a new generation of low-power, portable DNA analysis systems. [Copyright &y& Elsevier]

Abstract: This review surveys the advances of microvalves, micropumps, and micromixers within PCR microfluidic chips over the past ten years. First, the types of microvalves in PCR chips are discussed, including active and passive microvalves. The active microvalves are subdivided into mechanical (thermopneumatic and shape memory alloy), non-mechanical (hydrogel, sol–gel, paraffin, and ice), and external (modular built-in, pneumatic, and non-pneumatic) microvalves. The passive microvalves also include mechanical (in-line polymerized gel and passive plug) and non-mechanical (hydrophobic) microvalves. The review then discusses mechanical (piezoelectric, pneumatic, and thermopneumatic) and non-mechanical (electrokinetic, magnetohydrodynamic, electrochemical, acoustic-wave, surface tension and capillary, and ferrofluidic magnetic) micropumps in PCR chips. Next, different micromixers within PCR chips are presented, including passive (Y/T-type flow, recirculation flow, and drop) and active (electrokinetically-driven, acoustically-driven, magnetohydrodynamical-driven, microvalves/pumps) micromixers. Finally, general discussions on microvalves, micropumps, and micromixers for PCR chips are given. The microvalve/micropump/micromixers allow high levels of PCR chip integration and analytical throughput. [Copyright &y& Elsevier]

This paper presents a novel method for performing polymerase chain reaction (PCR) amplification by using spiral channel fabricated on copper where a transparent polytetrafluoroethylene (PTFE) capillary tube was embedded. The channel with 25 PCR cycles was gradually developed in a spiral manner from inner to outer. The durations of PCR mixture at the denaturation, annealing and extension zones were gradually lengthened at a given flow rate, which may benefit continuous‐flow PCR amplification as the synthesis ability of the Taq polymerase enzyme usually weakens with PCR time. Successful continuous‐flow amplification of DNA fragments has been demonstrated. The PCR products of 249, 500 and 982 bp fragments could be obviously observed when the flow rates of PCR mixture were 7.5, 7.5 and 3.0 mm s-1, respectively, and the required amplification times were about 25, 25, and 62 min, respectively. Besides, the successful segmented‐flow PCR of three samples (249, 500 and 982 bp) has also been reported, which demonstrates the present continuous‐flow PCR microfluidics can be developed for high‐throughput genetic analysis. [ABSTRACT FROM AUTHOR]

Abstract: The miniaturization of biological and chemical analytical devices by micro-electro-mechanical-systems (MEMS) technology has posed a vital influence on such fields as medical diagnostics, microbial detection and other bio-analysis. Among many miniaturized analytical devices, the polymerase chain reaction (PCR) microchip/microdevices are studied extensively, and thus great progress has been made on aspects of on-chip micromachining (fabrication, bonding and sealing), choice of substrate materials, surface chemistry and architecture of reaction vessel, handling of necessary sample fluid, controlling of three or two-step temperature thermocycling, detection of amplified nucleic acid products, integration with other analytical functional units such as sample preparation, capillary electrophoresis (CE), DNA microarray hybridization, etc. However, little has been done on the review of above-mentioned facets of the PCR microchips/microdevices including the two formats of flow-through and stationary chamber in spite of several earlier reviews [Zorbas, H. Miniature continuous-flow polymerase chain reaction: a breakthrough? Angew Chem Int Ed 1999; 38 (8):1055–1058; Krishnan, M., Namasivayam, V., Lin, R., Pal, R., Burns, M.A. Microfabricated reaction and separation systems. Curr Opin Biotechnol 2001; 12:92–98; Schneegaβ, I., Köhler, J.M. Flow-through polymerase chain reactions in chip themocyclers. Rev Mol Biotechnol 2001; 82:101–121; deMello, A.J. DNA amplification: does ‘small’ really mean ‘efficient’? Lab Chip 2001; 1: 24N–29N; Mariella, Jr. R. MEMS for bio-assays. Biomed Microdevices 2002; 4 (2):77–87; deMello AJ. Microfluidics: DNA amplification moves on. Nature 2003; 422:28–29; Kricka, L.J., Wilding, P. Microchip PCR. Anal BioAnal Chem 2003; 377:820–825]. In this review, we survey the advances of the above aspects among the PCR microfluidic devices in detail. Finally, we also illuminate the potential and practical applications of PCR microfluidics to some fields such as microbial detection and disease diagnosis, based on the DNA/RNA templates used in PCR microfluidics. It is noted, especially, that this review is to help a novice in the field of on-chip PCR amplification to more easily find the original papers, because this review covers almost all of the papers related to on-chip PCR microfluidics. [Copyright &y& Elsevier]

Abstract: This paper presents a practical system for automated 3-D road network reconstruction from aerial images using knowledge-based image analysis. The system integrates processing of color image data and information from digital spatial databases, extracts and fuses multiple object cues, takes into account context information, employs existing knowledge, rules and models, and treats each road subclass accordingly. The key of the system is the use of knowledge as much as possible to increase success rate and reliability of the results, working in 2-D images and 3-D object space, and use of 2-D and 3-D interaction when needed. Another advantage of the developed system is that it can correctly and reliably handle problematic areas caused by shadows and occlusions. This work is part of a project to improve and update the 1:25,000 vector maps of Switzerland. The system was originally developed to processed stereo images. Recently, it has been modified to work also with single orthoimages. The system has been implemented as a stand-alone software package, and has been tested on a large number of images with different landscape. In this paper, various parts of the developed system are discussed, and the results of our system in the tests conducted independently by our project partner in Switzerland, and the test results with orthoimages in a test site in The Netherlands are presented together with the system performance evaluation. [Copyright &y& Elsevier]

The extraction of road networks from aerial images is one of the current challenges in digital photogrammetry and computer vision. In this paper, we present a practical system for 3-D road network reconstruction from aerial images using knowledge-based image analysis. In contrast to other approaches, the developed system integrates processing of color image data and information from digital spatial databases, extracts and fuses multiple object cues, takes into account context information, employs existing knowledge, rules and models, and treats each road subclass accordingly. The key of the system is the use of knowledge as much as possible to increase success rate and reliability of the results, working in 2-D images and 3-D object space, and use of 2-D and 3-D interaction when needed. Another advantage of the developed system is that it can correctly and reliably handle problematic areas caused by shadows and occlusions. This work is part of a project to improve and update the 1:25,000 vector maps of Switzerland. The system has been implemented as a stand-alone software package, and has been tested on a large number of images with different landscape. In this paper, various parts of the developed system are discussed, and the results of our system in recent benchmark tests conducted independently by our project partner in Switzerland, and the test results with black and white images in a test site in Belgium are presented together with the system performance evaluation. [Copyright &y& Elsevier]

Cloth (or fabric) is an omnipresent material that has various applications in everyday life, and has become one of the things people are most familiar with. It has some attractive properties such as low cost, ability to transport fluid by capillary force, high tensile strength and durability, good wet strength, and great biocompatibility and biodegradability. Hence, cloth is an ideal material for the development of economical and user-friendly diagnostic devices for many applications including food detection, environmental monitoring, disease diagnosis and public health. Microfluidic cloth-based analytical devices (μCADs) (or microfluidic fabric-based analytical devices (μFADs)) first emerged in 2011 as a low-cost alternative to conventional laboratory testing, with the goal of improving point of care testing and disease screening in the developing world. In this review, we examine the advances in the development of μCADs from 2011 to 2020, especially highlighting emerging technologies and applications related to the μCADs. First, different fabrication methods for μCADs are introduced and compared. Second, a series of cloth-based microfluidic functional components are discussed, including microvalves, fluid velocity control elements, micromixers, and microfilters. Then, electroanalytical μCADs are described, especially focusing on the use of cloth-based electrodes. Next, various detection methods for μCADs, together with their corresponding applications, are compared and categorized. In addition, the current development of wearable μCADs is also demonstrated. Finally, the future outlook and trends in this field are discussed. • Different fabrication methods for μCADs are introduced and compared. • Cloth-based microfluidic functional components are discussed. • The use of electrodes in electroanalytical μCADs are described. • The detection methods and corresponding applications associated with μCADs are compared and categorized. • The current development of wearable μCADs is demonstrated. [ABSTRACT FROM AUTHOR]

In this work, we for the first time reported a paperfluidic crossing-channel closed-BPE based electrochemiluminescence (P-3C-BPE-ECL) platform where multiple “band”-shaped C-BPEs are situated perpendicular to two parallel channels, and multiplex detection can be achieved in the reporting channel. The paperfluidic devices are easily fabricated by wax and carbon ink-based screen-printing processes. Under optimized conditions, the P-3C-BPE-ECL is applied to the quantitative analysis of hydrogen peroxide (H 2 O 2 ) and glucose, with corresponding linear ranges of 0.075–10 mM and 0.08–5 mM, and corresponding detection limits of 0.041 mM and 0.03 mM. To our knowledge, this is the first demonstration of paperfluidic C-BPE-ECL method for glucose determination. Based on its acceptable selectivity, the P-3C-BPE-ECL method is used for measurements of glucose in four complex samples (human serum and urine, wine, and glucose injection) and is compared with the traditional methods. The results indicate a good agreement and prove the reliability and accuracy of the proposed platform. Importantly, the proposed method is demonstrated to have the potential for duplex detection of glucose and uric acid, which intensively matches the requirement of those patients simultaneously suffering from diabetes and gout. Therefore, we believe that the P-3C-BPE-ECL could provide a new platform for wide biochemical applications. [ABSTRACT FROM AUTHOR]

Hairpin probe (HP) is a metastable stem-loop structured oligonucleotide probe with a typical 5–8 bp short stem which has been widely applied in molecular biosensor. Usually, designing of HP with long stem should be avoided due to the impairment of recognition affinity, although it provides higher specificity and stability. Here we firstly designed an in-stem-mismatched hairpin probe, named mismatch-protected long-stem hairpin probe (mLSHP), and applied it to nicking endonuclease (NEase) assisted fluorescence biosensing of microRNA. Benefited from the specificity and affinity endowed by the high-stable stem-loop structure, the mLSHP enables high-selective target recognition. Moreover, the single base mismatch in the stem can protect the mLSHP from undesired stem invasion and NEase cleavage, thereby provide cooperative suppression of background leakage. Furthermore, the mLSHP also can be introduced into multilevel amplification system in a controlled and predictive mode for higher sensitivity and faster reaction rate. It is demonstrated that highly homologous microRNA-17 family members can be greatly discriminated with a detection limit of 2.5 fmol. In addition, the flexibility in probe design, simplicity in process control and expansibility in amplification mode make the smart biosensor holds a potential for further development and broader application in genetic diagnosis. [ABSTRACT FROM AUTHOR]

Automatic registration of multisensor data, for example, imagery and Light Detection And Ranging (LiDAR), is a basic step in data fusion in the field of geospatial information processing. Mutual information (MI) has recently attracted research attention as a statistical similarity measure for intensity-based registration of multisensor images in the related fields of computer vision and remote sensing. Since MI-based registration methods rely on joint probability density functions (pdfs) for the data sets, errors in pdf estimation can affect the MI value, causing registration failure due to the presence of nonmonotonic surfaces of similarity measure. The quality of the estimated pdf is highly dependent upon both the bin size and the smoothing technique used in the pdf estimation procedure. The lack of a general approach to assign an appropriate bin size value for the pdf of multisensor data reduces both the level of automation and the robustness of the registration. In this paper, a novel bin size selection approach is proposed to improve registration reliability. The proposed method determines the best (uniform or variable) bin size for the pdf estimation via an analysis of the relationship between the similarity measure values of the data and the adopted geometric transformation. This highlights the role of the component of MI sensitive to the transformation, rather than the MI component that is unrelated to the transformation, such as noise. The performance of the proposed method for the registration of aerial imagery to LiDAR point clouds is investigated, and experimental results are compared with those achieved through a feature-based registration method. [ABSTRACT FROM PUBLISHER]

This work demonstrates a smartphone-based automated fluorescence analysis system (SAFAS) for point-of-care testing (POCT) of Hg(II). This system consists of three modules. The smartphone module is used to provide an excitation light source, and to collect and analyze fluorescent images. The dark box module is applied to integrate the desired optical elements and offers a dark environment. The cost of the integrated dark box mainly includes the upper cover, box body, lower bottom, fixture and some optical elements which is about $109. The chip module is used for fluorescence sensing, which is composed of an upper plate, bottom plate and cloth-based chip. Due to the integration of multiple smartphone functions, the SAFAS eliminates the need for additional power sources, light sources and analysis systems. The dark box and upper and bottom plates are made by 3D printer. The cloth-based chip (about $0.005 for each chip) is fabricated using the wax screen-printing technique, with no need for expensive and complex fabrication equipments. To our knowledge, the cloth-based microfluidic fluorescence detection method combined with smartphone functions is first reported. By using optimal conditions, the designed system can realize the quantitative detection of Hg(II), which has a linear range of 0.001–100 μ g mL − 1 and a detection limit of 0.5 ng mL − 1 . Additionally, the SAFAS has been successfully applied for detecting Hg(II) in actual water samples, with recoveries of 100.1%–111%, RSDs of 3.88%–9.74%, and fast detection time of about 1 min. Obviously, the proposed SAFAS has the advantages of high sensitivity, wide dynamic range, acceptable reproducibility, good stability and low cost. Therefore, it is believed that the presented SAFAS has great potential to perform the POCT of Hg(II) in different water samples. [ABSTRACT FROM AUTHOR]

This work describes the first approach at combining microfluidic cloth-based analytical devices (μCADs) with electrochemiluminescence (ECL) detection. Wax screen-printing is employed to make cloth-based microfluidic chambers which are patterned with carbon screen-printed electrodes (SPEs) to create truly disposable, simple, inexpensive sensors which can be read with a low-cost, portable charge coupled device (CCD) imaging sensing system. And, the two most commonly used ECL systems of tris(2,2ʹ-bipyridyl)ruthenium(II)/tri-n-propylamine (Ru(bpy) 3 2+ /TPA) and 3-aminophthalhydrazide/hydrogen peroxide (luminol/H 2 O 2 ) are applied to demonstrate the quantitative ability of the ECL μCADs. In this study, the proposed devices have successfully fulfilled the determination of TPA with a linear range from 2.5 to 2500 μM with a detection limit of 1.265 μM. In addition, the detection of H 2 O 2 can be performed in the linear range of 0.05–2.0 mM, with a detection limit of 0.027 mM. It has been shown that the ECL emission on the wax-patterned cloth device has an acceptable sensitivity, stability and reproducibility. Finally, the applicability of cloth-based ECL is demonstrated for determination of glucose in phosphate buffer solution (PBS) and artificial urine (AU) samples, with the detection limits of 0.032 mM and 0.038 mM, respectively. It can be foreseen, therefore, that μCADs with ECL detection could provide a new sensing platform for point-of-care testing, public health, food safety detection and environmental monitoring in remote regions, developing or developed countries. [ABSTRACT FROM AUTHOR]

Colorimetric lateral flow immunoassay (LFIA) is a widely used point-of-care testing (POCT) technology, while it has entered a bottleneck period because of low detection sensitivity, expensive preparation materials, and incapable quantitative detection. Therefore, it is necessary to develop a novel POCT method that is ultrasensitive, simple, portable, and capable of accurately detecting biomarkers in biofluids daily, particularly for pregnancy preparation and early screening of diseases. In this work, a novel dry chemistry-based self-enhanced electrochemiluminescence (DC-SE-ECL) LFIA sensor is introduced for accurate POCT of luteinizing hormone (LH). The proposed DC-SE-ECL immunosensor significantly improves the detection sensitivity through the Poly- l -Lysine (PLL)-based SE-ECL probe and cathode modification of closed bipolar electrode (C-BPE). Additionally, a new type of C-BPE configuration is designed for easily performing the LFIA. And, two standalone absorbent pads are symmetrically arranged below the reporting channel of the electrode pad to decease useless residues on the detection pad, which further improves the detection performance. Under optimized conditions, the proposed LFIA sensor has a low limit of detection (9.274 μIU mL−1) and a wide linear dynamic range (0.01–100 mIU mL−1), together with good selectivity, repeatability and storage stability. These results indicate that the proposed DC-SE-ECL method has the potential as a new tool for detecting biomarkers in clinical samples. [Display omitted] • A novel DC-SE-ECL LFIA sensor was applied for detection of LH. • The sensitivity was greatly improved through the SE-ECL probe and cathode modification. • The LFIA strip was easily fabricated by using various cloth materials. • The portable ECL analyzer was used for rapid immunodetection (about 6 min). • The detection limit was 9.274 μIU mL −1, and the linear range was from 0.01 to 100 mIU mL−1. [ABSTRACT FROM AUTHOR]

In this work, we successfully developed a cloth-based device integrated with a photoelectrochemical (PEC) cell and ion imprinting for point-of-care testing (POCT) of divalent mercury ions (Hg(Ⅱ)). PEC cells have increasingly emerged as promising power supply units in recent years. The CdS/ZnS core-shell quantum dots (QDs) are used in the PEC cell, because they improve the spatial separation and transfer of charge and broaden the absorption of visible light. Ion imprinting can identify a specific metal ion selectively in the presence of other interfering ions. To achieve noninterference identification, the QDs-based PEC cell region is isolated from the ion imprinting-based detection area. In addition, wax screen-printing can be used in conjunction with carbon ink screen-printing for economical and facile fabrication of cloth-based devices. Under optimized conditions, Hg(Ⅱ) can be determined over the range of 0.0005–5 mg/L, with a detection limit of 0.090 µg/L (i.e., 0.45 nM). The proposed cloth-based devices are also applied successfully for the detection of Hg(Ⅱ) in sweat, complex water and food samples, with recoveries of 98.2–116.1% and relative standard deviations (RSDs) of 1.2–13.9%. Additionally, cloth-based devices have acceptable storage stability and selectivity. Therefore, the presented method offers a sensitive, low-cost, portable POCT device and has the potential to be applied for human body, environmental and food monitoring in remote areas and developing or industrialized countries. [Display omitted] • The lab-on-cloth device is creatively integrated with PEC cell and ion imprinting, and applied for detection of Hg(Ⅱ). • The PEC cell composed of core-shell quantum dots can provide the required energy for the highly sensitive detection. • The detection area and the cell energy supply area are separated to avoid possible mutual interference. • The molecular imprinting is introduced into the lab-on-cloth device and improves the selectivity of Hg(Ⅱ) detection. • The method has achieved the POCT of Hg(Ⅱ), with a wide dynamical range, low detection limit and fast analytical speed. [ABSTRACT FROM AUTHOR]

Abstract: The development of robust and accurate methods for automatic registration of optical imagery and 3D LiDAR data continues to be a challenge for a variety of applications in photogrammetry, computer vision and remote sensing. This paper proposes a new approach for the registration of optical imagery with LiDAR data based on the theory of Mutual Information (MI), which exploits the statistical dependency between same- and multi-modal datasets to achieve accurate registration. The MI-based similarity measures quantify dependencies between aerial imagery, and both LiDAR intensity data and 3D point cloud data. The needs for specific physical feature correspondences, which are not always attainable in the registration of imagery with 3D point clouds, are avoided. Current methods for registering 2D imagery to 3D point clouds are first reviewed, after which the mutual MI approach is presented. Particular attention is given to adoption of the Normalised Combined Mutual Information (NCMI) approach as a means to produce a similarity measure that exploits the inherently registered LiDAR intensity and point cloud data so as to improve the robustness of registration between optical imagery and LiDAR data. The effectiveness of local versus global similarity measures is also investigated, as are the transformation models involved in the registration process. An experimental program conducted to evaluate MI-based methods for registering aerial imagery to LiDAR data is reported and the results obtained in two areas with differing terrain and land cover, and with aerial imagery of different resolution and LiDAR data with different point density are discussed. These results demonstrate the potential of the MI and especially the CMI methods for registration of imagery and 3D point clouds, and they highlight the feasibility and robustness of the presented MI-based approach to automated registration of multi-sensor, multi-temporal and multi-resolution remote sensing data for a wide range of applications. [Copyright &y& Elsevier]

Abstract: The ability to perform DNA amplification on a microfluidic device is very appealing. In this study, a compact continuous-flow polymerase chain reaction (PCR) microfluidics was developed for rapid analysis of genetically modified organisms (GMOs) in genetically modified soybeans. The device consists of three pieces of copper and a transparent polytetrafluoroethylene capillary tube embedded in the spiral channel fabricated on the copper. On this device, the P35S and Tnos sequences were successfully amplified within 9min, and the limit of detection of the DNA sample was estimated to be 0.005ng μl−1. Furthermore, a duplex continuous-flow PCR was also reported for the detection of the P35S and Tnos sequences in GMOs simultaneously. This method was coupled with the intercalating dye SYBR Green I and the melting curve analysis of the amplified products. Using this method, temperature differences were identified by the specific melting temperature values of two sequences, and the limit of detection of the DNA sample was assessed to be 0.01ng μl−1. Therefore, our results demonstrated that the continuous-flow PCR assay could discriminate the GMOs in a cost-saving and less time-consuming way. [Copyright &y& Elsevier]

• A wearable cloth-based electrochemical sensor (WCECS) is proposed. • The good sweat collection channels and sweat transport channel are obtained. • The WCECS is easily fabricated, low-cost, skin-friendly and secure-safe. • The WCECS has an acceptable analytical performance. • The WCECS can be applied for in vitro sweat monitoring and duplex detection. Wearable electrochemical (EC) biosensors have attracted tremendous attention for noninvasive diagnosis and point-of-care testing (POCT) of individual health level. The analysis of glucose concentration in epidermal sweat presents a promising means of noninvasive continuous glucose monitoring for diabetes mellitus. The previous focus has been mainly on pursuing novel EC sensing materials to achieve highly sensitive biosensors. In this work, a novel flexible three-dimensional (3-D) wearable cloth-based EC sensor (WCECS) has been proposed for analysis of glucose in sweat. The WCECS possesses excellent sweat collection channels and cloth-based sweat transport channel. Notably, the transport channel is actuated by the capillary force to absorb the sweat into the cloth-based chip which can be easily and inexpensively fabricated by the screen-printing technology. Under optimized conditions, the WCECS can well measure the concentrations of glucose in sweat over the range of 0.05−1 mM, with an acceptable sensitivity of 105.93 μA mM−1 cm−2. Besides, the WCECS exhibits excellent selectivity, reproducibility and stability. Importantly, the EC responses of the WCECS have a good correlation with those of the glucometer, and are consistent with the results by the glucose kit. Moreover, the WCECS can be applied for constant 9 h wearable monitoring, and for simultaneous detection of lactic acid and glucose in sweat. So, the proposed approach may represent an important step toward the promising application of the cloth-based sensor for daily personalized health monitoring. [ABSTRACT FROM AUTHOR]

In this work, a cloth-based chemiluminescence (CL) biosensor has been firstly presented for highly sensitive determination of long PCR amplicons. Under the action of a hybridization chain reaction, a good deal of hemin/G-quadruplex DNAzyme molecules are produced, which can effectively enhance the CL signal. Moreover, effective cloth-based DNA biosensors can be fabricated by sequential wax screen-printing and surface-modification processes. Especially, the integration of a desirable hydrophobic barrier and gravity/capillary flow onto the flow channel of the cloth-based device makes the biosensor easy to be fabricated and to be associated with a flow CL. For the luminol/H2O2-based CL system, the signals are triggered by the hemin/G-quadruplex DNAzyme and are recorded by a low-cost CCD. Under optimized conditions, the determination range of target DNA is 0.002–20,000 pM and its limit of detection is calculated to be 1.1 fM. The results show that the proposed CL biosensor has a good analytical performance, such as high detectability and specificity, wide linear range, and receivable reproducibility and stability. Finally, the proposed biosensor is proven by the fact that this method can successfully detect the target DNA prepared from the Listeria monocytogenes–spiked milk samples. Therefore, it is believed to have the potential application prospects in food safety and environmental monitoring. [ABSTRACT FROM AUTHOR]

In this work, a solely gravity and capillary force-driven flow chemiluminescence (GCF-CL) paper-based microfluidic device has been proved for the first time as a new platform for inexpensive, usable, minimally-instrumented dynamic chemiluminescence (CL) detection of chromium (III) [Cr(III)], where an appropriate angle of inclination between the loading and detection zones on the paper produces a rapid flow of CL prompt solution through the paper channel. For this study, we use a cost-effective paper device that is manufactured by a simple wax screen-printing method, while the signal generated from the Cr(III)-catalyzed oxidation of luminol by H2O2 is recorded by a low-cost and luggable CCD camera. A series of GCF-CL affecting factors have been evaluated carefully. At optimal conditions, two linear relationships between GCF-CL intensities and the logarithms of Cr(III) concentrations are obtained in the concentration ranges of 0.025–35 mg/L and 50–500 mg/L separately, with the detection limit of 0.0245 mg/L for a less than 30 s assay, and relative standard deviations (RSDs) of 3.8%, 4.5% and 2.3% for 0.75, 5 and 50 mg/L of Cr(III) (n = 8). The above results indicate that the GCF-CL paper-based microfluidic device possesses a receivable sensitivity, dynamic range, storage stability and reproducibility. Finally, the developed GCF-CL is utilized for Cr(III) detection in real water samples. [ABSTRACT FROM AUTHOR]

As a good biomarker to reflect the average level of blood glucose, glycated hemoglobin (HbA1c) is mainly used for long-term glycemic monitoring and risk assessment of complications in diabetic patients. Previous analysis methods for HbA1c usually require complex pretreatment processes and large-scale biochemical analyzers, which makes it difficult to realize the point-of-care testing (POCT) of HbA1c. In this work, we have proposed a three-electrode dry chemistry-based electrochemiluminescence (ECL) biosensor and its self-contained automatic ECL analyzer. In this enzymatic biosensor, fructosyl amino-caid oxidase (FAOD) reacts with the hydrolysis product of HbA1c, and the produced hydrogen peroxide further reacts with luminol under the appropriate driving voltage, generating photons to realize the quantitative detection of HbA1c. Under optimized conditions, the biosensors have a good linear response to different concentrations of fructosyl valine (FV) ranging from 0.05 to 2 mM, with a limit of detection of 2 μM. The within-batch variation is less than 15%, and the biosensors still have 78% of the initial response after the accelerated aging test of 36 h at 37 °C. Furthermore, the recoveries for different concentrations of samples in whole blood were within 92.3–99.7%. These results illustrate that the proposed method has the potential for use in POCT of HbA1c. [Display omitted] • The dry chemistry-based ECL strategy is firstly applied for detection of HbA1c. • The enzymatic method and layer-by-layer structure are applied. • The self-made analyzer reduces the detection cost and makes the POCT possible. • The self-made potentiostat can be suitable for multiple detection scenes. • The LOD of HbA1c is 1 μM with high specificity, and without complex modifications. [ABSTRACT FROM AUTHOR]

Luteinizing hormone (LH) is a gonadotropin, and its concentration is closely related to the female ovulation cycle. However, the traditional lateral flow method for LH detection has poor sensitivity and sustainability. In this work, a dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor (μFIS) has been firstly proposed for electrochemiluminescence (ECL) point-of-care testing (POCT) of LH. The μFIS was composed of four-layer fiber material (paper and cloth)-based pads, and was combined with closed bipolar electrode-ECL (CBPE-ECL) to quantitatively detect LH. The CBPE-ECL μFIS not only retained the high sensitivity and wide linear range associated with CBPE-ECL, but also reserved the simplicity and practicality of the lateral flow assay. In addition, a self-enhanced intramolecular ECL probe was incorporated into the μFIS for signal amplification. Under optimized conditions, the μFIS had a very low detection limit (0.125 μIU mL-1) and positive linear relationship (0.001–100 mIU mL-1), together with excellent selectivity, reproducibility and storage stability. Moreover, the CBPE-ECL μFIS was applied to detect LH in human clinical serum samples, and the results had a good correlation with those of clinical samples. These results revealed that the CBPE-CEL μFIS had the potential as a high-performance POCT for LH or other biomarkers. [Display omitted] • A novel dry chemistry-based ECL immuosensor was applied for detection of LH. • The self-enhanced Ru(II)-PLL complex was applied for ultrasensitive detection. • The microfluidic chip was easily fabricated with cloth and filter paper. • The automatic portable ECL analyzer was used for rapid detection (about 8 min). • The detection limit was 0.125 μIU mL-1, and the linear range is from 0.001 to100 mIU mL-1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescence detection of proteins on cloth is firstly proposed. • Non-woven cloth is firstly used to make the test strip. • A smartphone is used to capture images and display the results via an APP. • The point-of-care testing system can achieve the sample-to-answer detection. • The IgE levels in complex human serum samples can be measured. In the work, a novel fluorescence point-of-care testing (POCT) system was developed for sample-to-answer detection of immunoglobulin E (IgE), which is the first time that a cloth material has been applied to the fluorescence detection of proteins. The system included an lateral/vertical flow-based microfluidic (LVFM) model, POCT detector, and smartphone-based data processing module. In the LVFM model, the non-woven cloth and screen-printing methods were applied to break the restrictions of traditional lateral flow strips on nitrocellulose membrane material and fabrication method. The 3D-printed POCT detector was used to supply a dark environment, with advantages of small volume, lightweight, and being easy-to-use. The smartphone-based data processing module was applied for image acquisition, image analysis and data display. After the fluorescent image was taken, the image analysis was carried out by the self-developed APP. By using the proposed POCT system, on the optimized conditions, the desired IgE detection was obtained, with a linear dynamic detection range of 10–1000 ng mL−1, and detection limit of 8.5 ng mL−1. In addition, the presented system showed good selectivity, repeatability and stability, and had the potential to be used in the field of detection of allergic diseases. [ABSTRACT FROM AUTHOR]

Abstract In this work, a novel facile closed bipolar electrochemiluminescence (C-BP-ECL) sensor has been developed for highly sensitive detection of glucose based on the integration of chitosan (CS), poly(diallyldimethylammonium chloride)-functioned multi-walled carbon nanotubes (PDDA-MWCNTs) and graphene quantum dots-gold nanoparticles (GQDs-AuNPs) on the wax/carbon ink-screen-printed cloth-based device. When CS, PDDA-MWCNTs and GQDs-AuNPs are successively decorated onto the cathode of closed bipolar electrode (C-BPE), the C-BPE anode can emit much stronger C-BP-ECL signals. Moreover, the cathodic decoration of the C-BPE can generate a stronger ECL signal in comparison with its anodic decoration. Under optimized conditions, glucose can be detected in the range of 0.1–5000 μM, and the limit of detection is estimated to be 64 nM, which is about three orders of magnitude lower than that in case of the bare C-BPE cathode (31 μM). It has been shown that the proposed sensor has high detection sensitivity, wide dynamic range, and as well acceptable reproducibility, selectivity and stability. Finally, the applicability and validity of the C-BP-ECL sensor are demonstrated for the detection of glucose in human serum samples. We believe that this novel highly-sensitive sensor will have potential applications in various areas such as clinical diagnosis, food analysis and environmental monitoring. Highlights • A highly sensitive cloth-based C-BP-ECL sensor with nanostructured electrode surface is presented. • The CS, PDDA-MWCNTs and GQDs-AuNPs are used for electrode-decorated materials. • The C-BP-ECL with the cathodic decoration can produce a stronger signal. • The glucose concentrations in complex human serum samples can be measured. • The fabrication of the sensor is simple, rapid, inexpensive and less instrumented. [ABSTRACT FROM AUTHOR]

As one of the most common noninfectious diseases, diabetes and diabetic complications (DDC) have attracted great attention in the field of life and health. However, simultaneous detection of DDC markers usually requires labor- and time-consuming steps. Here, a novel cloth-based single-working-electrode electrochemiluminescence (SWE-ECL) sensor was designed for the simultaneous detection of multiple DDC markers. For this sensor, three independent ECL cells are distributed on the SWE, which is a simplification of the configuration of traditional sensors for simultaneous detection. In this way, the modification processes and ECL reactions occur at the back of the SWE, eliminating the adverse effects caused by human intervention on the electrode. Under optimized conditions, glucose, uric acid and lactate were determined, with corresponding linear dynamic ranges of 80–4000 μM, 45–1200 μM and 60–2000 μM, and detection limits of 54.79 μM, 23.95 μM and 25.82 μM, respectively. In addition, the cloth-based SWE-ECL sensor exhibited good specificity and satisfactory reproducibility, and its actual application potential was verified by measuring complex human serum samples. Overall, this work developed a simple, sensitive, low-cost and rapid method for the simultaneous quantitative determination of multiple markers related to DDC and demonstrated a new route for multiple-marker detection. [Display omitted] • A cloth-based SWE-ECL sensor is reported for the first time. • The sensor is proposed to detect multiple diabetes and diabetic complications markers. • The simultaneous ECL determination of three markers only uses one SWE. • The modification processes and ECL reactions occur at the back of the SWE. • The sensor is simple, cost-effective, portable and environmentally friendly. [ABSTRACT FROM AUTHOR]

Liver disease causes serious public health problems because of its high prevalence, particularly affecting low- and middle-income countries. Alanine transaminase (ALT) is considered to be one of the most sensitive indicators for diagnosing liver disease. Although many strategies have been reported for ALT detection, few of them have solved the problem of automatic detection. In this work, for the first time, a dry chemistry-based electrochemiluminescence (DC-ECL) device is developed for point-of-care testing (POCT) of ALT, achieving real sample-to-answer detection. The proposed DC-ECL device consists of the following two components: (a) a DC-ECL chip consisting of the outer shell (including the top cap and pedestal) and detection layer (including the baseplate, electrode pad and carrier pad) and (b) an automatic ECL analyzer mainly including the data processing and instrument control unit, imaging detection unit, electrochemical reaction excitation unit, open detection window unit and rechargeable power supply. Under optimized conditions, the device had a wide detection range (0–1000 U/L), the ECL intensity linearly increased with ALT concentration (5–50 U/L) and logarithmic ALT concentration (50–1000 U/L), and the limit of detection was calculated to be 1.702 U/L. In addition, the DC-ECL device had the ability to measure ALT levels in human serum samples and showed acceptable selectivity, stability and repeatability. These results reveal that the DC-ECL device can overcome the disadvantages of traditional methods for ALT detection (such as high cost and requirement of professional technicians) and potentially opens the door to the development of similar POCT analyzers. [Display omitted] • A novel dry chemistry-based ECL device is developed for the first time. • The device can be used as a potential analysis tool for basic hospitals and homes. • The automatic ECL analyzer has realized the real sample-to-answer detection. • The proposed work is expected to promote the development of POCT devices. [ABSTRACT FROM AUTHOR]

In this work, a novel strategy to construct coin-sized, multifunctional micropatterned cloth devices (μPCDs) based on programmable fluid transport has been reported for the first time. A photolithography technique is used to fabricate μPCDs that operate as simple disposable colorimetric sensors. This fabrication method allows hydrophobic barriers to be well integrated onto the cloth channels to form programmable cloth-based diagnostic devices. In the present study, several different programmable μPCDs were designed and fabricated, including basic μPCDs, μPCDs with parallel or serial fluidic paths, and μPCDs with serial-parallel fluidic paths. The fluid transport in the resulting μPCDs was programmed to provide qualitative or quantitative analyses. The μPCDs with serial-parallel fluidic paths were used as prototypes for qualitative detection of glucose concentration, pH, and protein concentration in artificial urine (AU) samples. Moreover, a single cloth-based device could be programmed for sequential reaction processes, and the quantitative detection of nickel(II) ions in water, nitrite ions in AU, and glucose in AU by two-step enzymatic reactions was achieved. The results indicate that the developed programmable μPCDs can provide a new sensing platform for other biochemical assays. [ABSTRACT FROM AUTHOR]

Cloth fabrics and smartphones have become the two things people are most familiar with. Particularly, smartphones are used as portable personal computers, revolutionizing communication and lifestyle. Here, screen-printing technology is applied to fabricate carbon electrodes and electrochemical chambers on a single hydrophilic cloth, while the cloth-based electrochemiluminescence (ECL) signals are read out by using an inexpensive smartphone. Therefore, the ECL detection is available in both low-cost disposable sensors and a portable format, which may be very suitable to be used as a non-invasive monitoring tool for medical diagnostics. As a proof-of-principle, lactate oxidase is immobilized onto the working electrode for the lactate measurement. Under optimized conditions, the lactate levels can be quantified over the range of 0.05–2.5 mM, with a detection limit of 0.035 mM and the relative standard deviations of 4.7%, 5.2% and 5.0% for 0.05, 0.5 and 2.5 mM lactate (n = 5). In addition, the proposed biosensor has an acceptable stability and selectivity. Finally, the ECL biosensor is successfully applied for the determination of lactate in human saliva. These results show that the presented ECL platform has the potential to be applied to non-invasively detect a variety of analytes of medical interest. [ABSTRACT FROM AUTHOR]

This paper introduces a new and simple concept for fabricating low-cost, easy-to-use capillary microchannel (CMC) assisted thread-based microfluidic analytical devices (CMCA-μTADs) for bipolar electrochemiluminescence (BP-ECL) application. The thread with patterns of carbon screen-printed electrodes and bare thread zones (BTZs) is embedded into a CMC. Such CMCA-μTADs can produce a strong and stable BP-ECL signal, and have an extremely low cost ($0.01 per device). Interestingly, the CMCA-μTADs are ultraflexible, and can be bent with a 135° bending angle at the BTZ or with a 150° bending angle at the middle of bipolar electrode (BPE), with no loss of analytical performance. Additionally, the two commonly-used ECL systems of Ru(bpy) 3 2+ /TPA and luminol/H 2 O 2 are applied to demonstrate the quantitative ability of the BP-ECL CMCA-μTADs. It has been shown that the proposed devices have successfully fulfilled the detection of TPA and H 2 O 2 , with detection limits of 0.00432 mM and 0.00603 mM, respectively. Based on the luminol/H 2 O 2 ECL system, the CMCA-μTADs are further applied for the glucose measurement, with the detection limit of 0.0205 mM. Finally, the applicability and validity of the CMCA-μTADs are demonstrated for the measurements of H 2 O 2 in milk, and glucose in human urine and serum. The results indicate that the proposed devices have the potential to become an important new tool for a wide range of applications. [ABSTRACT FROM AUTHOR]

In this work, we firstly report a novel battery-triggered open wireless electrochemiluminescence (O-WL-ECL) sensing strategy based on the microfluidic cloth-based bipolar devices (μCBPDs). The carbon ink-screen-printing is used to fabricate the bipolar electrodes (BPEs) and driving electrodes on the cloth which is patterned with wax-screen-printed hydrophilic channels to create low-cost sensors ($0.011 per device) which can be powered with a rechargeable battery and read with an inexpensive, portable charge coupled device (CCD) camera. Moreover, the widely-used luminol/hydrogen peroxide (H 2 O 2 ) ECL reaction has been performed to illustrate the quantitative ability of the O-WL-ECL μCBPDs. Under optimized conditions, the μCBPDs can achieve the measurement of H 2 O 2 , with a linear range of 0.025–10 mM and a detection limit of 0.024 mM. Additionally, the determination of glucose can be carried out in the linear range from 0.025 mM to 10 mM, with a detection limit of 0.023 mM. It has been shown that the O-WL-ECL on μCBPDs has an acceptable sensitivity, stability and reproducibility. Finally, this simple and cost-effective device is successfully applied for the measurements of H 2 O 2 in milk and glucose in clinical urine and serum samples. Therefore, the proposed methodology could provide great promise in applications in many areas, and may facilitate the achievement of point-of-care testing. [ABSTRACT FROM AUTHOR]

Chemiluminescence (CL) has been widely applied in many fields, but it is rarely used in a very simple, economical but effective way. In this work, for the first time, the CL cloth-based glucose test sensors (CCGTSs) are developed as a new class of CL glucose sensors, with no need for complicated, expensive device fabrication and peripheral equipment. When integrated with desirable hydrophobic barrier in the flow channel and gravity/capillary flow induced by a difference in height between the loading zone and the detection zone, a single cloth-based device can perform the whole CL process involving two steps of enzyme reactions. The wax screen-printing approach is used to fabricate ultra-cheap CCGTSs, the glucose detection involves the enzymatic oxidation of glucose to gluconic acid and H 2 O 2 followed by the horseradish peroxidase (HRP)-catalyzed oxidation of luminol by H 2 O 2 , and the emitted CL signals are heightened with p-iodophenol (PIP) and imaged using an inexpensive, portable CCD camera. Under optimized conditions, glucose can be determined over the range of 0.1–100 mM, with a detection limit of 0.0948 mM and an analysis time of less than 5.5 min. Finally, the applicability and validity of the CCGTSs are demonstrated for the measurement of glucose in clinical urine and serum samples. Thus, the proposed sensors could provide great promise in applications in many areas, and may facilitate the achievement of point-of-care testing. [ABSTRACT FROM AUTHOR]

Flow chemiluminescence (CL) is widely applied for detection of heavy metal ions in environment, but it is seldom used in economical, practical, or affordable settings because non- and minimally instrumented flow driving is difficult to achieve. Here, we first report a gravity and capillary force-driven flow CL (GCF-CL) lab-on-cloth device, toward development of low-cost, easy-to-use, portable, minimally-instrumented platform for determination of trivalent chromium [Cr(III)] in water, where a difference in height between two zones on cloth creates a fast flow of CL trigger solution. Wax screen-printing was used to fabricate ultra-low-cost cloth-based devices, and the light emitted from the Cr(III)-catalysed oxidation of luminol by H 2 O 2 was imaged using an inexpensive portable CCD camera. Under optical conditions, Cr(III) could be determined over the range of 0.01–100 mg/L, with a detection limit of 6.2 μg/L, an analysis time of less than 30 s per sample, and RSDs of 6.2%, 3.1% and 1.7% for 0.05, 0.5 and 5 mg/L Cr(III) (n = 5). The proposed GCF-CL lab-on-cloth was successfully applied for measuring Cr(III) in water samples, with recoveries of 100.67-111.70% and RSDs of 4.73–6.88%. Thus, the presented method should have the potential for portable field applications in environmental and public health fields. [ABSTRACT FROM AUTHOR]

The rising need for low-cost diagnostic devices has led to the search for inexpensive matrices that allow performing alternative analytical assays. Cloth is a viable material for the development of analytical devices due to its low material and manufacture costs, ability to wick assay fluids by capillary forces, and potential for patterning multiplexed channel geometries. In this paper, we describe the construction of low-cost, ultraflexible microfluidic cloth-based analytical devices (μCADs) for wireless electrochemiluminescence based on closed bipolar electrodes (C-WL-ECL), employing extremely cheap materials and a manufacturing process. The C-WL-ECL μCADs are built with wax-screen-printed cloth channels and carbon ink screen-printed electrodes, and the estimated cost per device is only $0.015. To demonstrate the performance of C-WL-ECL μCADs, the two most commonly used ECL systems – tris(2,2′-bipyridyl)ruthenium(ii)/tri-n-propylamine (Ru(bpy)32+/TPA) and 3-aminophthalhydrazide/hydrogen peroxide (luminol/H2O2) – are applied. Under optimized conditions, the C-WL-ECL method has successfully fulfilled the quantitative determination of TPA with a detection limit of 0.085 mM. In addition, on the bent μCADs (bending angle (ϑ) = 180°), the luminol/H2O2-based ECL system can detect H2O2 as low as 0.024 mM. Based on such an ECL system, the bent μCADs are further used for determination of glucose in a phosphate buffer solution (PBS), with the detection limit of 0.195 mM. Finally, the applicability and validity, anti-interference ability, and storage stability of the C-WL-ECL μCADs are investigated. The results indicate that the proposed device has shown potential to extend the use of microfluidic analytical devices, due to its simplicity, low cost, ultraflexibility, and acceptable analytical performance. [ABSTRACT FROM AUTHOR]

Dry chemistry-based fluorescence or colorimetric immunosensors have been widely applied for point-of-care testing (POCT). However, dry chemistry-based electrochemiluminescence (ECL) immunosensors have not been reported for real sample-to-answer detection. Herein, a dry chemistry-based sample-to-answer, ultrasensitive closed bipolar electrode-ECL (CBP-ECL) immunosensor based on lateral flow assay has been firstly designed for POCT of Cardiac Troponin I (cTnI). The CBP-ECL immunosensor consisted of a fiber material-based chip and an outer shell, which were easily and affordably fabricated by screen-printing and 3D printing, respectively. Additionally, the Ru(Ⅱ)-L-Cys composite, as a self-enhanced ECL probe, was firstly introduced into the sandwich CBP-ECL immunosensor. The ECL signal generated by labeled antibody functionalized Ru(Ⅱ)-L-Cys could quantify cTnI sensitively. Therefore, the immunosensor had a wide linear range (0.001–100 ng/mL) and acceptable sensitivity (0.4416 pg/mL), together with superior specificity and good reproducibility and stability. Furthermore, the immunosensor was capable of detection of cTnI in serum, with recoveries of 97.3–103.4%. For detection of cTnI in plasma samples, the results of the proposed CBP-ECL had a good correlation with those of the clinical method. Importantly, the analysis process easily operated, and completed in 7 min. These results illustrated that the proposed immunosensor effectively combined the high sensitivity of CBP-ECL with the simplicity of lateral flow assay, and provided a promising POCT avenue for early diagnosis of acute myocardial infarction (AMI) and other diseases. [ABSTRACT FROM AUTHOR]