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Simple geometrical modifications for substantial color intensity and detection limit enhancements in lateral-flow immunochromatographic assays
摘要： One of the ongoing challenges in lateral flow Immunochromatographic assays (LFIA), is lowering the limit of detection and enhancing their signal quality, i.e. the color intensity. There are a number of rather costly and complicated processes for this aim, such as the use of functionalized materials/membranes and additional spectroscopic readout units. Nonetheless, there are simple and easy to practice alternatives, to be uncovered by analyzing the essential parameters of immunological reactions. The color intensity of the test line is a function of analytes flow velocity and their reaction rate. Detection pad width and test line position impact the flow velocity and reaction rate kinetics, examined in this paper for the limit of detection (LOD) and test-line color intensity. Firstly, the impact of width on the LOD was examined for human chorionic gonadotropin (pregnancy biomarker). Test line color intensity was measured using five different widths of the detection pad (trapezoidal) and four different test line positions, and the trends observed were explained according to the measured evolution of the velocity along the chromatography paper. With a constant width absorbent pad, LOD was cut by half to 5 mIU/ml by using a narrowing width detection pad, which keeps the wicking velocity higher than normal strips, and compared to them, color intensity increase between 55-150%, depending on the concentration. Nevertheless, a widening detection pad might cut the color intensity up to 150%, compared to normal strips, due to a profound decline of the analyte to ligand ratio at the test line. In addition, adequately sending the test line away from the conjugate pad yields the highest possible color intensity, for up to 400% of increase, in lower concentrations and narrowing test pads. However, further distancing the test line downfalls the color intensity.
关键词： Lateral Flow Immunochromatographic Assays,Trapezoidal Geometry,Limit of Detection,Detection Pad,Capillary Flow Velocity,Porous Medium,Color Intensity,Test Line Displacement
更新于2025-09-19 17:15:36
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Experimental investigation on premixed hydrogen/air combustion in varied size combustors inserted with porous medium for thermophotovoltaic system applications
摘要： Micro combustion stabilization is challenged by the large heat loss ratio, and the operating conditions are narrow because of the small combustor size. In this work, experimental tests combined with numerical simulations are carried out to investigate the premixed H2-air combustion with and without porous medium. The results indicate that the flame stabilization is greatly enhanced in the combustor with porous medium, and the wall temperature with porous medium is 188 K higher than that of the free flame in the tube with a length 22 mm, an outer diameter 7 mm and the wall thickness 0.5 mm. The appropriate porosity of porous medium is selected for each combustor to achieve a better thermal performance and high radiation temperature. With the increase of combustor diameter, the limitations in terms of inlet velocity and flame blowout are expanded and the radiation surface area is also increased for a higher energy output. The radiation temperature and surface area play important roles in the application of micro thermo-photovoltaic system. The combustor with a length 27 mm and an outer diameter 7 mm is able to achieve an optimal balance between the contingent negative variation of radiation surface area and radiation temperature, delivering an electrical power of 1.41 W with an efficiency 1.39% for the micro-TPV system with InGaAsSb PV cells when the H2 flow rate is 3.03 g/h and equivalence ratio Φ = 0.85.
关键词： Micro combustion,Porous medium,Porosity,Electrical power
更新于2025-09-11 14:15:04
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<i>(Invited)</i> Water Transport Along Si/Si Direct Wafer Bonding Interfaces
摘要： The transport of water in a highly confined gap made by the direct bonding of low roughness silicon hydrophilic wafers is studied. We derive the equation for the transport of water from chemical potential gradients, using Stokes and conservation equations. The transport equation is found to be a Porous Medium Equation with exponent 2. A solution for this equation with stepwise boundary conditions is given. The model is tested against different initial conditions for inward and outward flow, and different temperatures and humidity levels.
关键词： silicon direct bonding,chemical potential gradients,Porous Medium Equation,water transport,hydrophilic wafers
更新于2025-09-10 09:29:36