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A portable and universal upconversion nanoparticle-based lateral flow assay platform for point-of-care testing
摘要： Upconversion nanoparticle-based lateral flow assays (UCNP-LFAs) have attracted significant attention in point-of-care testing (POCT) applications, due to the long-term photostability and enhanced signal-to-background noise ratio. The existing UCNP-LFAs generally require peripheral equipment for exciting fluorescent signals and reading out fluorescence results, which are generally bulky and expensive. Herein, we developed a miniaturized and portable UCNP-LFA platform, which is composed of a LFA detection system, an UCNP-LFA reader and a smartphone-assisted UCNP-LFA analyzer. The LFA detection system is based on three types of UCNPs for multiplexed detection. The reader has a dimension of 24.0 cm×9.4 cm×5.4 cm (L×W×H) and weight of 0.9 kg. The analyzer based on the custom-designed software of a smartphone (termed as UCNP-LFA analyzer) can get the quantitative analysis results in a real-time manner. We demonstrated the universality of this platform by highly sensitive and quantitative detections of several kinds of targets, including small molecule (ochratoxin A, OTA), heavy metal ion (Hg2+), bacteria (salmonella, SE), nucleic acid (hepatitis B virus, HBV) and protein (growth stimulation expressed gene 2, ST-2). Our developed UCNP-LFA platform holds great promise for applications in disease diagnostics, environmental pollution monitoring and food safety at the point of care.
关键词： UCNP-based biosensor,telemedicine,point-of-care diagnostics,paper microfluidics,multiplexed detection,miniaturized device
更新于2025-11-28 14:23:57
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Precise label-free leukocyte subpopulation separation using hybrid acoustic-optical chip
摘要： Leukocyte subpopulations contain crucial physiological information; hence, precise and specific leukocyte separation is very important for leukemia diagnosis and analysis. However, conventional centrifugation and immunofluorescence-based separation methods are inaccurate and inconvenient due to the overlapping cell size and density or complex marking processes. Herein, we report a new label-free technology for precise leukocyte subpopulation separation by synergy of acoustic and optical technologies. Standing surface acoustic wave (SSAW) solved the problem of gentle and precise focusing of cells in optical systems. In addition, SSAW was used for the separation of granulocytes, which have evident size distinction from other components. In case of lymphocytes and monocytes, which have overlap in size/density, optical force could distinguish them accurately based on the RI difference, with the convenience of acoustic pre-focusing. In this experiment, separation of three types of leukocyte subtypes with considerable throughput and purity was conducted, through which we obtained 99% pure lymphocytes, 98% pure monocytes, and 95% pure granulocytes. Experimental results prove that the device has robust ability in separating leukocyte phenotypes and have the advantages of being non-invasive, label-free and precise. In the future, this convenient hybrid method will be a potential powerful tool for auxiliary clinical diagnosis and analysis.
关键词： label-free,cell sorting,microfluidics,acoustic-optical chip,leukocyte separation
更新于2025-11-25 10:30:42
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Sacrificial Layer Technique for Releasing Metallized Multilayer SU-8 Devices
摘要： The low fabrication cost of SU-8-based devices has opened the fields of point-of-care devices (POC), μTAS and Lab-on-Chip technologies, which call for cheap and disposable devices. Often this translates to free-standing, suspended devices and a reusable carrier wafer. This necessitates a sacrificial layer to release the devices from the substrates. Both inorganic (metals and oxides) and organic materials (polymers) have been used as sacrificial materials, but they fall short for fabrication and releasing multilayer SU-8 devices. We propose photoresist AZ 15nXT (MicroChemicals GmbH, Ulm, Germany) to be used as a sacrificial layer. AZ 15nXT is stable during SU-8 processing, making it suitable for fabricating free-standing multilayer devices. We show two methods for cross-linking AZ 15nXT for stable sacrificial layers and three routes for sacrificial release of the multilayer SU-8 devices. We demonstrate the capability of our release processes by fabrication of a three-layer free-standing microfluidic electrospray ionization (ESI) chip and a free-standing multilayer device with electrodes in a microchannel.
关键词： microfabrication,microfluidics,free standing,microchips,SU-8,sacrificial release,multi layered chips,AZ 15nXT
更新于2025-09-23 15:23:52
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Nanomechanical Microfluidic Mixing and Rapid Labelling of Silica Nanoparticles with Allenamide to Thiol Covalent Link for Bioimaging
摘要： Rapid surface functionalization of nanomaterials using covalent linkage following ‘green chemistry’ remains challenging and the quest for developing simple protocols are persisting. We report a nanomechanical microfluidic approach for the coupling of allenamide functionalized organic derivatives on the surface of thiol modified silica nanoparticles using allenamide-thiol chemistry. The coupling principle involves the use of a microfluidic surface acoustic wave (SAW) device that generates acoustic streaming based chaotic fluid micromixing that enables mixing of laterally flowing fluids containing active components. This approach was used to demonstrate the direct surface labeling of thiol modified silica nanoparticles using a selected group of modified fluorescence tags containing allenamide handles and achieved a total efficiency of 83-90 %. This green approach enabled a highly efficient surface functionalization in aqueous conditions, with tunable control over the conjugation process via the applied field. The dye labelled silica particles were characterized using various analytical techniques and found to be biocompatible with a potential in live cell bioimaging. It is envisaged that this bioconjugation strategy will find numerous applications in the field of bioimaging and drug delivery.
关键词： microfluidics,surface acoustic wave (SAW),allenamide-thiol chemistry,bioimaging,nanoparticles
更新于2025-09-23 15:23:52
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Regenerable Bead-Based Microfluidic Device with integrated THIN-Film Photodiodes for Real Time Monitoring of DNA Detection
摘要： Nanoporous microbead-based microfluidic systems for biosensing applications allow enhanced sensitivities, while being low cost and amenable for miniaturization. The regeneration of the microfluidic biosensing system results in a further decrease in costs while the integration of on-chip signal transduction enhances portability. Here, we present a regenerable bead-based microfluidic device, with integrated thin-film photodiodes, for real-time monitoring of molecular recognition between a target DNA and complementary DNA (cDNA). High-sensitivity assay cycles could be performed without significant loss of probe DNA density and activity, demonstrating the potential for reusability, portability and reproducibility of the system.
关键词： microfluidics,regenerable biosensor,DNA detection,a-Si:H photodiodes,fluorescence
更新于2025-09-23 15:23:52
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Construction of Self-Healing Internal Electric Field for Sustainably Enhanced Photocatalysis
摘要： The construction of internal electric field is generally considered an effective strategy to enhance photocatalytic performance due to its significant role in charge separation. However, static internal electric field is prone to be saturated either by inner or outer shield effect, and thus its effect on the improvement of photocatalysis can easily vanish. Here, the self-healing internal electric field is proposed and successfully endowed to a designed helical structural composite microfiber polyvinylidene fluoride/g-C3N4 (PVDF/g-C3N4) based on the bioinspired simple harmonic vibration. Importantly, the saturation and recovery of internal electric field are characterized by transient photovoltage and photoluminescence. The results indicate that the internal electric field could be saturated within about 10 min and refreshed with the assistance of rebuilt piezoelectric potential. The lifetime of photogenerated carriers is about 10?4 s and the number of effective carriers is greatly increased in the presence of self-healing internal electric field. The results provide direct experimental evidence on the role of self-healing internal electric field in charge transfer behavior. This work represents a new design strategy of photocatalysts, and it may open up new horizons for solving energy shortage and environmental issues.
关键词： charge separation,photocatalysis,microfluidics,bioinspired,self-healing
更新于2025-09-23 15:23:52
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Magnetic SERS Composite Nanoparticles for Microfluidic Oil Reservoir Tracer Detection and Nanoprobe Applications
摘要： Composite magnetic nanoparticles are designed and synthesized with different morphologies as surface-enhanced Raman scattering (SERS) substrates or SERS-active particles. Through the incorporation of a magnetic functionality we provide a means to concentrate SERS-active nanoparticles in a low-volume microfluidic channel where the detected entity is now either a flowing analyte (e.g. tracer or chemical) or SERS-active particles contained in a target reservoir fluid. This collection strategy allows for detection using small amounts of material and can be optimized to provide selectivity for trace-level materials detection at the wellsite. We also demonstrate low-concentration detection of dye molecules used for reservoir tracer materials by optimizing the fluid flow rate and the intensity of the magnetic field. Thus, we developed an efficient magnetic SERS microfluidic detection platform for in situ monitoring trace level of analyte molecules. The integration of SERS with microfluidic systems also can extends the application of Raman detection in bio-medical research and microreactor monitoring where low volumes of expensive samples make traditional detection methods ineffective or cost prohibitive.
关键词： surface-enhanced Raman scattering,SERS nanoprobes,magnetic SERS,SERS substrate,nanoparticle,microfluidics
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Cleveland, OH, USA (2018.10.17-2018.10.19)] 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Monitoring Red Blood Cell Aggregation Dynamics in Stasis and Under Flow Using a Microfluidic Dielectric Sensor
摘要： This paper reports on monitoring the red blood cell (RBC) aggregation dynamics under flow and in static condition using a microfluidic dielectric sensor. The sensor employs a three-dimensional (3D), parallel-plate, capacitive sensing structure with a floating electrode integrated into a microfluidic channel with a height of 50μm. Using an impedance analyzer, the sensor is shown to measure the real part of complex relative dielectric permittivity of human whole blood in a frequency range of 10kHz–100MHz under flow and in static condition. The dielectric permittivity of human whole blood at 1MHz indicates the formation of RBC aggregate structures called rouleaux under static condition and their complete breakdown under a physiological shear flow rate of 500s-1. This work also demonstrates that the kinetics of RBC aggregation is dependent on fibrinogen concentration of the blood sample and establishes that the sensor is capable of distinguishing this difference in the aggregation process even under physiological shear flow rates. This work demonstrates the potential of dielectric spectroscopy in obtaining information on RBC aggregation dynamics using μL-volumes of whole blood under flow and in stasis.
关键词： red blood cells,capacitive sensor,dielectric spectroscopy,Aggregation,rouleaux formation,microfluidics
更新于2025-09-23 15:23:52
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Compensation method of error caused from maladjustment of optical path based on microfluidic chip
摘要： Photometric detection plays a significant role in microfluidics technology. However, the mismatch between the solution concentration and the optical path length will increase detection error. In this study, we proposed a round microfluidic chip for concentration detection to obtain the continuous gradient distribution of concentration. The optimum absorbance can be found by dynamic accurately searching. The solution concentration will be accurately calculated finally according to the relationship between arc length and solution concentration. The overall detection process runs automatically. Under the optimization of injection velocity and concentration, the experimental result shows that the compensation ratio increases as the solution concentration increases. The compensation ratio in the detection of pesticide residue has already reached 14.22% and the reproducibility is acceptable. Therefore, this novel method lays the theoretical foundation for the research of high precision microfluidic photometric detection equipment.
关键词： Microfluidics,concentration detection,photometric detection,optical path length
更新于2025-09-23 15:23:52
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Photolithographic Patterning of Cytop with Limited Contact Angle Degradation
摘要： Cytop is a commercially available amorphous fluoropolymer with excellent characteristics including electric insulation, water and oil repellency, chemical resistance, and moisture-proof property, making it an attractive material as hydrophobic layers in electrowetting-on-dielectric (EWOD) devices. However, its highly hydrophobic surface makes it difficult for photoresists to be directly coated on the surface. To pattern Cytop, plasma treatment prior to applying photoresists is required to promote the adhesion between the photoresist and the Cytop coating. This approach inevitably causes hydrophobicity loss in the final EWOD devices. Thus, a damage-reduced recipe for Cytop patterning is urgently needed. In this paper, we first characterized the damage caused by two categories of surface treatment methods: plasma treatment and metal treatment. Parameters such as plasma gas source (Ar/O2), plasma treatment time (0–600 s), metal target (Al/Cu/Cr/Au), metal deposition process (magnetron sputtering or e-beam evaporation) were varied. Film thickness, wettability, and roughness were quantified by ellipsometry measurements, contact angle measurements, and atom force microscope (AFM), respectively. We then evaluated the effectiveness of annealing in damage reduction. Experimental results show that: (1) annealing is necessary in restoring hydrophobicity as well as smoothing surfaces; (2) specified film thickness can be obtained by controlling plasma treatment time; (3) “Ar/O2 plasma treatment + an AZ5214 soft mask + annealing” is a feasible recipe; (4) “an Al/Cu/Cr/Au hard mask + annealing” is feasible as well.
关键词： Cytop,electrowetting-on-dielectric (EWOD),annealing,patterning,microfluidics
更新于2025-09-23 15:23:52