Optical fiber-based nanoindenter featuring automated measurement.

Area of Science:

• Materials Science
• Biophysics
• Optical Engineering

Background:

• Nanoindentation is crucial for micro- and nanoscale mechanical testing.
• Accurate measurements depend on high-resolution sensing and signal readout.
• Existing methods may have limitations in stability and automation.

Purpose of the Study:

• To present an improved fiber-optic nanomechanical probe (FONP) and a dedicated automated nanoindentation system.
• To demonstrate the system's accuracy, stability, and automation capabilities.
• To investigate the mechanical properties of biological cells and polymer samples.

Main Methods:

• Fabrication of the FONP using femtosecond laser two-photon polymerization.
• Development of a fiber-optic nanoindentation system with Fabry-Pérot interferometric optical readout.
• Incorporation of an optical shielding layer for spectral stability without gold coating.
• Automated array-based Young's modulus mapping and time-dependent mechanical evolution studies.

Main Results:

• The enhanced FONP achieved spectral stability with a cross-correlation coefficient of 1.
• Investigated onion epidermal cells during dehydration, observing an increase in Young's modulus.
• Automated Young's modulus mapping of PDMS samples showed <10% deviation from a commercial nanoindenter.

Conclusions:

• The proposed fiber-optic interferometric nanoindentation system offers accurate, stable, and automated nanomechanical characterization.
• The system is suitable for investigating time-dependent mechanical properties of biological samples.
• Demonstrated potential for compact and robust nanomechanical analysis in various scientific fields.