Comprehensive model of electromigrative transport in microfluidic paper based analytical devices

Area of Science:

• Analytical Chemistry
• Physical Chemistry
• Materials Science

Background:

• Electromigration is crucial for separation techniques in analytical devices.
• Paper-based analytical devices (PADs) offer low-cost, portable platforms for chemical analysis.
• Modeling electromigration in porous media like paper presents unique challenges due to complex fluid dynamics and transport phenomena.

Purpose of the Study:

• To develop a comprehensive mathematical model for electromigration in paper-based analytical devices.
• To systematically analyze and consolidate contributions to electromigration modeling in porous media.
• To introduce and investigate a novel electrophoretically driven dispersive transport mechanism.

Main Methods:

• Derivation of differential equations for fluid motion (pressure-driven flow and electroosmotic flow), charged species transport, and electric potential distribution.
• Application of an effective medium approach to represent the porous cellulose fiber network using macroscopic parameters.
• Utilizing scaling laws and incorporating additional terms to adapt open-channel equations for porous media.

Main Results:

• Effective parameters for diffusion, mobility, and conductivity in porous media were derived.
• Numerical simulations based on the model showed good agreement with experimental data.
• The model successfully simulated complex free-flow electrophoresis in a 2D paper geometry, including capillary flow.

Conclusions:

• The developed mathematical model provides a robust framework for understanding and predicting electromigration in paper-based analytical devices.
• The proposed model validates experimental findings and offers insights into transport mechanisms within porous materials.
• This work advances the capabilities for designing and optimizing paper-based microfluidic devices for various analytical applications.