Fluidic Device for Polydisperse Component Diffusion Analysis
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Solution Overview
Problem
Current methods for analyzing polydisperse mixtures, such as protein associations, face challenges in accurately measuring the diffusion coefficients and hydrodynamic radii of individual components due to fluid stagnation and the limitations of existing microfluidic diffusion techniques, which often provide average values rather than component-specific data.
Innovation Solution
A method involving a fluidic device with a large cross-section channel to minimize fluid stagnation and a small cross-section channel for precise diffusion measurements, allowing for the determination of diffusion coefficients and hydrodynamic radii of multiple components by measuring lateral diffusion at multiple times, enabling the deconvolution of individual component profiles from mixed samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a T-junction microchannel is used for diffusion measurement, then the device structure is simple, but fluid stagnation occurs at the junction causing measurement errors
Solution Approach 1:
The microchannel is divided into three distinct sections: a mixing section where fluids are introduced, a diffusion section where lateral diffusion occurs, and a detection section where measurements are taken. This segmentation eliminates the stagnation problem at the junction by separating the mixing function from the diffusion measurement function, allowing accurate diffusion coefficient measurements.
Solution Approach 2:
A carrier fluid is introduced as an intermediary substance that flows alongside the analyte-containing fluid. The carrier fluid serves as a medium for lateral diffusion without causing stagnation, enabling the analyte to diffuse laterally while maintaining continuous flow conditions throughout the channel.
2Ease of operation
If conventional diffusion techniques are used, then the method is simple, but only average diffusion values are obtained for polydisperse mixtures
Solution Approach 1:
The diffusion process is analyzed at multiple lateral positions across the channel width, effectively segmenting the diffusion measurement into multiple spatial zones. Each position provides information about diffusion at different times, enabling the resolution of individual component diffusion coefficients from polydisperse mixtures through deconvolution of the spatial profile.
Solution Approach 2:
The measurement transitions from a single-point detection to a spatially-resolved measurement across the lateral dimension of the channel. By measuring fluorescence intensity at multiple lateral positions, the system captures the diffusion profile as a function of position, which contains information about multiple diffusion coefficients that can be extracted through mathematical analysis.
3Measurement precision
If fluorescent labeling is used for diffusion measurement, then detection sensitivity is improved, but sample preparation complexity increases
Solution Approach 1:
The system is designed to work with fluorescently labeled analytes, where the fluorescence detection capability serves multiple functions: tracking the analyte distribution, measuring diffusion coefficients, and enabling detection in polydisperse mixtures. The fluorescent label becomes a universal marker that provides comprehensive information about the labeled species throughout the diffusion process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides accurate and precise measurements of diffusion coefficients and hydrodynamic radii for individual components in complex mixtures, overcoming the limitations of existing techniques by reducing noise and resolving individual components within polydisperse samples.
Implementation Method 1
The analyte diffuses from the analyte fluid into the carrier fluid as the flows proceed along the channel
Implementation Method 2
The two streams of fluid are brought into contact at the T-junction and are permitted to flow side by side along a detection channel
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
Provided is a method for determining the diffusion of one or more components, the method comprising the steps of (i) providing a component fluid flow comprising one or more components; (ii) providing a blank fluid flow; (iii) bringing the flow (i) into contact with the flow (ii) in a large cross section channel, thereby to generate two laminar flows; (iv) permitting the laminar flows generated in (iii) to flow from the large cross section channel into a small cross section channel; (v) measuring the lateral diffusion of the one or more components from the component flow into the blank fluid flow in the small cross section channel. Also provided is a diffusion method comprising the steps of measuring the lateral diffusion of the one or more components from the component flow into the blank fluid flow at a plurality of diffusion times. Also provided is a method of determining the composition of a fluid comprising a plurality of components (i) providing one or more measured diffusion profiles for the fluid comprising the plurality of components; (ii) providing a series of predicted distributions for components having known hydrodynamic radii; and (iii) deconvoluting the measured lateral diffusion profiles of the one or more components using a highest entropy regularisation approach with reference to the series of distributions for components having known hydrodynamic radii.