High-Throughput Mechanical Characterization of Single Microgel Particles by Fluidic Force Microscopy.

Area of Science:

• Materials Science
• Soft Matter Physics
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) based nanoindentation is standard for soft materials but time-consuming for individual microgel particles.
• Accurate mechanical characterization of microgels requires measuring a large number of particles due to broad Young's moduli distribution.
• Current methods face challenges in efficiently analyzing numerous micrometer-sized particles.

Purpose of the Study:

• To develop a novel, high-throughput nanoindentation technique for soft particulate materials.
• To reverse the roles of the indenter and sample in nanoindentation using Fluidic Force Microscopy (FluidFM).
• To enable faster and more versatile mechanical characterization of microgels.

Main Methods:

• Developed an 'inverted' nanoindentation approach utilizing Fluidic Force Microscopy (FluidFM).
• Microgel particles are aspirated onto a FluidFM cantilever and indented against a flat substrate.
• Experimental validation performed on polyoxazoline-hyaluronic acid (POx-HASH) and polyacrylamide (PAAm) microgels.

Main Results:

• The inverted nanoindentation method achieves Young's moduli measurements 5-10 times faster than conventional AFM nanoindentation.
• The technique successfully characterizes mechanical properties of diverse microgel types.
• Measurements can be performed on various substrates, allowing investigation of adhesion effects.

Conclusions:

• The inverted nanoindentation technique offers a significant advancement in the efficient mechanical characterization of microgel particles.
• This method provides statistically reliable data more rapidly, crucial for understanding microgel behavior.
• The versatility of the technique opens new avenues for studying soft matter interactions and substrate effects.