Controlling particle dynamics in dead-end channels via boundary effects

Area of Science:

• Physics
• Chemistry
• Engineering

Background:

• Controlled particle transport is vital for drug delivery and environmental remediation.
• Diffusiophoresis (DP) is established for particle manipulation, but diffusioosmosis (DO) is less explored.
• Microfluidic systems offer precise control over particle movement in confined spaces.

Purpose of the Study:

• To systematically investigate the interplay between diffusiophoresis and diffusioosmosis for active particle control.
• To analyze particle transport in microfluidic dead-end pores using solute gradients and wall zeta potentials.
• To develop a theoretical framework for understanding and optimizing particle manipulation without external power.

Main Methods:

• Theoretical modeling of coupled diffusiophoresis and diffusioosmosis.
• Experimental validation of particle transport in microfluidic dead-end pores.
• Analysis of diffusioosmotic mobility dependence on zeta potential and solute properties.

Main Results:

• Precise manipulation of colloidal particles achieved by exploiting solute concentration gradients and wall zeta potentials.
• Identified parameter ranges for controlling the sign of diffusioosmotic mobility.
• Introduced a critical reversal position (y*) and developed scaling laws and regime maps for particle behavior.

Conclusions:

• The study provides fundamental insights into electrokinetic phenomena in confined geometries.
• Offers a theoretical framework for optimizing microfluidic designs for efficient particle transport.
• Paves the way for passive, energy-efficient microfluidic systems for biomedical and environmental applications.