A High Accuracy Ion Conductance Imaging Method Based on the Approach Curve Spectrum

Area of Science:

• Nanotechnology
• Surface Science
• Biomedical Engineering

Background:

• Scanning ion conductance microscopy (SICM) is a non-contact, in situ topography measurement tool with nano-resolution.
• Conventional SICM methods use a constant ion current threshold, which can lead to inaccurate probe-sample distance and inconsistent topography measurements for diverse structures.

Purpose of the Study:

• To develop a novel ion conductance imaging method for SICM to improve measurement accuracy.
• To address the limitations of constant feedback thresholds in conventional SICM.

Main Methods:

• A new SICM imaging method based on approach curve spectra is proposed.
• Local sample features are evaluated using ion current change rates.
• Approach curves are searched from a prior spectrum to accurately determine probe-sample distance.
• Topography is constructed by subtracting the probe-sample distance from the probe position.

Main Results:

• The feasibility of the new imaging method was verified through finite element theory and experiments.
• Testing on silicon and polydimethylsiloxane (PDMS) samples showed improved topography closer to real surfaces.
• The improved method reduced volumetric measurement error by 5.4%.

Conclusions:

• The proposed approach curve spectrum method significantly enhances SICM measurement accuracy.
• This advancement has the potential to further promote SICM applications in biomedicine, electrochemistry, and materials science.