Operation of astigmatic-detection atomic force microscopy in liquid environments

Area of Science:

• Nanotechnology
• Biophysics
• Optical Metrology

Background:

• The astigmatic detection system (ADS) offers sub-nanometer sensitivity for vertical movement detection in air.
• Its sub-micrometer laser spot and >80 MHz bandwidth are suitable for high-frequency mechanical resonance detection in nanotechnology.

Purpose of the Study:

• To optimize the ADS for operation in aqueous solutions.
• To demonstrate its capability for high-resolution imaging of biological and material samples in liquid environments.

Main Methods:

• Optimized operational parameters of the ADS for aqueous solutions.
• Employed optical profilometry mode for imaging cancer cells in water.
• Developed an Astigmatic Detection System-Atomic Force Microscopy (ADS-AFM) with a novel cantilever holder.
• Suppressed spurious resonance peaks in ADS-AFM to 26.0% of real peaks.

Main Results:

• Achieved good contrast and spatial resolution for cancer cells in water using optical profilometry.
• Demonstrated successful imaging of soft DNA molecules on mica in water using ADS-AFM.
• Resolved single atomic steps on a graphite substrate with ADS-AFM in aqueous conditions.

Conclusions:

• The optimized ADS demonstrates effective high-resolution imaging in aqueous solutions.
• ADS-AFM provides a viable platform for nanoscale imaging of biological and material science samples in liquid.
• This technology holds significant potential for applications in nanotechnology and biophysics.