Two-photon photopolymerized tips for adhesion-free scanning-probe microscopy

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Atomic Force Microscopy (AFM) is a high-resolution surface imaging technique.
• Tip-sample adhesion to hydrophilic surfaces can impede imaging performance in AFM.
• Developing specialized AFM tips is crucial for overcoming current limitations.

Purpose of the Study:

• To fabricate novel hydrophobic polymeric tips for AFM using two-photon adsorbed photopolymerization (TPAP).
• To evaluate the performance of these hydrophobic tips in imaging various sample types.
• To demonstrate the capability of the fabricated tips in resolving fine surface topographies.

Main Methods:

• Fabrication of hydrophobic polymeric tips via layer-by-layer polymerization of 3D CAD data using TPAP.
• Utilizing a "dynamic partial polymerization method" and the "threshold effect" for enhanced fabrication resolution.
• Imaging organic, inorganic, and biological samples in contact or dynamic force modes.

Main Results:

• The fabricated polymeric tips exhibited inherent hydrophobic properties due to the acrylate and epoxy resin composition.
• Hydrophobic tips effectively mitigated tip adhesion problems encountered with hydrophilic sample surfaces.
• Achieved a topographic image resolution of sub-5 nanometers on a hydrophilic mica surface.

Conclusions:

• The developed hydrophobic polymeric AFM tips offer a significant advancement for high-resolution surface analysis.
• These tips provide a robust solution for imaging challenging hydrophilic surfaces, reducing artifacts.
• The TPAP fabrication method enables precise control over tip geometry and properties for specialized AFM applications.