研究目的
To investigate the scaling behavior in on-chip field-amplified sample stacking (FASS) through theoretical scaling analysis, numerical simulations, and experiments, focusing on the effects of electric field, conductivity gradient, and electroosmotic flow on stacking dynamics.
研究成果
The scaling analysis successfully identifies two distinct regimes in on-chip FASS: diffusion-dominated and convection-dominated, governed by specific time scales. Validation through simulations and experiments shows that dimensionless variables collapse data onto single curves, providing insights into parameter effects. To achieve high concentration enhancement, the convection-dominated regime should be avoided by ensuring low Peclet numbers or longer analysis times. This work has practical significance for optimizing on-chip FASS in applications like large volume sample stacking.
研究不足
The theoretical analysis assumes constant mobility and diffusivity of ionic species, which may not hold for all electrolyte chemistries. The scaling analysis is simplified and may not account for effects like Joule heating or three-dimensional flow near channel junctions. Experiments are limited to specific microchannel dimensions and analyte types, and the Taylor dispersion regime is not always attained in on-chip FASS due to short preconcentration times.
1：Experimental Design and Method Selection:
The study employs a theoretical scaling analysis to identify two stacking regimes (diffusion-dominated and convection-dominated) in FASS, validated through numerical simulations and on-chip experiments. The design rationale is to understand the transient growth of peak concentration and width under varying conditions.
2：Sample Selection and Data Sources:
Samples include an anionic analyte (e.g., fluorescein) mixed with low-conductivity electrolyte. Data sources include numerical simulations using COMSOL Multiphysics and SPRESSO tools, and experimental data from on-chip FASS experiments in glass microchannels, as well as published data from Bharadwaj and Santiago (2005).
3：5).
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes a cross-shaped glass microchannel (Micronit, The Netherlands), high voltage power supply (Ionics, India), inverted epifluorescence microscope (Nikon Eclipse Ti-U, Japan), CCD camera (PCO pixelfly, PCO AG, Germany), and COMSOL Multiphysics software (COMSOL AB, Stockholm, Sweden). Materials include sodium hydroxide, MOPS (Sigma Aldrich, USA), sodium fluorescein (CDH, India), and deionized water.
4：Experimental Procedures and Operational Workflow:
Experiments involve establishing a sharp conductivity gradient in a microchannel, applying an electric field to induce stacking, and capturing time-resolved images using fluorescence microscopy. Numerical simulations solve convection-electromigration-diffusion equations with appropriate boundary conditions.
5：Data Analysis Methods:
Data analysis includes calculating peak concentration and full width at half maximum (FWHM) from averaged snapshots, using dimensionless variables derived from scaling analysis to collapse data onto single curves for validation.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
