Taylor dispersion and the position-to-time conversion in microfluidic mixing devices

Area of Science:

• Biomolecular dynamics
• Microfluidics
• Chemical kinetics

Background:

• Microfluidic mixing devices are essential for studying non-equilibrium biomolecular dynamics.
• Hydrodynamic focusing enables sub-millisecond reaction initiation in microfluidic systems.
• Accurate conversion of position to time is vital for kinetic analysis but complicated by Taylor dispersion.

Purpose of the Study:

• To develop an accurate position-to-time conversion method for microfluidic devices that accounts for Taylor dispersion across all time regimes.
• To quantify the impact of Taylor dispersion on the time resolution of microfluidic mixing devices, particularly for single-molecule fluorescence detection.
• To bridge the gap in position-to-time conversion accuracy between early and late time limits.

Main Methods:

• Detailed three-dimensional, time-dependent finite-element calculations were employed.
• The method provides an accurate position-to-time conversion, bridging early and late time regimes.
• Calculated velocity fields were validated against experimental dual-focus fluorescence correlation spectroscopy measurements.

Main Results:

• A robust method for position-to-time conversion in microfluidic devices was established, overcoming limitations of previous approaches.
• The study quantifies the influence of Taylor dispersion on the achievable time resolution.
• The finite-element calculations demonstrated high accuracy when compared to experimental data.

Conclusions:

• The developed method enables precise kinetic studies in microfluidic systems by accurately converting spatial positions to reaction times.
• Understanding and quantifying Taylor dispersion is critical for optimizing microfluidic device design and improving time resolution.
• This work enhances the utility of microfluidic devices for probing fast biomolecular processes.