Injection by hydrostatic pressure in conjunction with electrokinetic force on a microfluidic chip

Area of Science:

• Microfluidics
• Analytical Chemistry
• Biotechnology

Background:

• Microfluidic devices offer advantages for sample manipulation and analysis.
• Precise sample injection is crucial for effective separation and analysis in microfluidic systems.
• Traditional methods often require complex and bulky equipment for sample manipulation.

Purpose of the Study:

• To develop a simple and efficient method for sample injection into microfluidic chips.
• To utilize hydrostatic pressure combined with electrokinetic forces for sample manipulation.
• To demonstrate the feasibility of this method for cell analysis and sample separation.

Main Methods:

• A cross-form microfluidic chip was employed for sample injection.
• Hydrostatic pressure was generated by adjusting liquid levels in reservoirs, eliminating the need for pumps.
• Two injection strategies, floating and gated injection, were tested.
• Fluorescence observation was used to verify the separation of fluorescein sodium salt and fluorescein isothiocyanate.

Main Results:

• The developed method successfully achieved sample injection using hydrostatic pressure and electrokinetic forces.
• Both floating and gated injection strategies proved effective.
• The method demonstrated successful separation of fluorescent dyes, validating its utility.
• The technique was effective in guiding cells into a separation channel for single-cell analysis.

Conclusions:

• A simple, pump-free method for sample injection on microfluidic chips was successfully developed.
• The combination of hydrostatic pressure and electrokinetic forces offers a viable alternative for sample manipulation.
• This technique is suitable for cell analysis and the separation of complex mixtures in microfluidic systems.