Volume and concentration dosing in picolitres using a two-channel microfluidic AFM cantilever

Area of Science:

• Nanotechnology
• Microfluidics
• Atomic Force Microscopy

Background:

• Atomic Force Microscopy (AFM) is a powerful tool for nanoscale imaging and manipulation.
• Precise control of small fluid volumes is crucial for various applications, including single-cell analysis.

Purpose of the Study:

• To develop a novel two-channel microfluidic AFM cantilever.
• To integrate fluid manipulation capabilities with AFM's nanomechanical sensing.
• To enable precise dosing and concentration control of picoliter fluid volumes.

Main Methods:

• Fabrication of a two-channel microfluidic AFM cantilever with nanoscale apertures.
• Independent pressure control of fluid reservoirs connected to each channel.
• Systematic experiments using fluorescent liquids for injection and aspiration.
• Analytical modeling based on hydrodynamic resistance and numerical flow simulations.
• Flow rate and concentration dosing analysis.

Main Results:

• Achieved flow rates from 10 fl/s to 83 pl/s within the cantilever channels.
• Demonstrated precise dosing flow rates as low as 720 fl/s.
• Tuned solute concentration in outflow between 0% and 100% via convection, and 17.5% to 90% with diffusion.
• Validated experimental results with analytical and numerical flow models.

Conclusions:

• The developed microfluidic AFM cantilever effectively integrates fluid handling with AFM functionalities.
• This technology allows for the precise manipulation of multiple fluids and analyte concentrations.
• Potential applications include injecting diverse analyte concentrations into single living cells and performing standard AFM tasks.