Experimental determination of sample stream focusing with fluorescent dye

Area of Science:

• Microfluidics
• Analytical Chemistry
• Biophysics

Background:

• Accurate determination of focused-sample stream width is crucial in microfluidic devices.
• Conventional methods like FWHM intensity are limited by dye properties and accuracy.
• Developing a robust, dye-independent method is essential for reliable microfluidic analysis.

Purpose of the Study:

• To develop a novel experimental method for determining focused-sample stream width in microfluidic chips.
• To establish a method that is insensitive to sample and dye properties.
• To validate the proposed method against existing techniques.

Main Methods:

• Utilizing the Gaussian distribution of the cross-stream concentration profile downstream of the junction.
• Estimating stream width from channel dimensions and experimentally measured concentration profile variance and maximum concentration.
• Validating the method using fluorescein dye and comparing results with FWHM and analytical methods.

Main Results:

• The proposed method accurately determines focused-sample stream width.
• The method is independent of fluorescent dye properties, unlike the FWHM method.
• Experimental validation confirmed the proposed method's accuracy and reliability.

Conclusions:

• The developed experimental method provides an accurate and dye-independent approach for measuring focused-sample stream width.
• This method offers a significant improvement over existing techniques for microfluidic sample analysis.
• The findings have implications for optimizing microfluidic device design and performance.