Quantifying and Utilizing Electroosmotic Flow for Mechanical Measurements with the Scanning Ion Conductance...

Area of Science:

• Nanotechnology
• Biophysics
• Materials Science

Background:

• Scanning ion conductance microscopy (SICM) is used for nanoscale imaging in liquids.
• Mechanical measurements with SICM typically rely on hydrostatic pressure-induced flow.
• Existing methods face limitations in probing delicate samples.

Purpose of the Study:

• To introduce and validate electroosmotic flow (EOF) for mechanical SICM measurements.
• To quantify EOF parameters and compare its efficacy to hydrostatic pressure.
• To demonstrate the application of EOF for nanoscale mechanical property mapping.

Main Methods:

• Utilized EOF within SICM nanopipettes for mechanical probing.
• Quantified electroosmotic mobility via streaming current measurements.
• Developed a numerical model to determine sample stiffness and Young's modulus.
• Applied EOF-based method to decane microdroplets and living cells.

Main Results:

• EOF-induced flow in SICM nanopipettes is comparable to hydrostatic pressure.
• Successfully measured stiffness and Young's modulus of elastic samples using EOF.
• Obtained quantitative Young's modulus mapping of living cells with EOF.
• EOF method yielded results consistent with hydrostatic pressure methods.

Conclusions:

• Electroosmotic flow is a viable alternative to hydrostatic pressure for mechanical SICM.
• EOF enables quantitative nanoscale stiffness measurements of various samples.
• This technique expands the capabilities of SICM for mechanical characterization.