With the scaling of semiconductor technology toward sub-micron length scales, the accurate measurement of this property with high spatial resolution has become increasingly important. In biology, there is also a growing interest in determining the dielectric constant at the nanoscale. Here, the property plays a key role in processes such as membrane potential formation, action potential propagation, and ion membrane transport. Standard thin film characterization techniques are not suited for this purpose as they probe large-areas of the sample.

To satisfy the demand for information at much smaller length scales, the group has developed a simple method of measuring the static dielectric constant, which is applicable to a wide range of thin film structures from solid state materials to biomembranes.

Using an accurate analytical model, the researchers can extract the dielectric constant from DC electrostatic force measurements made with a commercial AFM. The method has been validated on thin silicon dioxide films and purple membrane monolayers, providing results that are in excellent agreement with those recently obtained by nanoscale capacitance microscopy using a current-sensing approach.

Currently, the group is further improving the precision of the measurement and is extending the method to a liquid environment.

The team presented its work in Nanotechnology.

About the author

The authors belong to the Nanoscale Bioelectrical Characterization Group at the Institute of Bioengineering of Catalonia (IBEC), Barcelona, Spain. The main goal of the group is the development of experimental setups based on atomic force microscopy and of adequate theoretical frameworks to measure and understand the electrical properties of biological samples (for example, biomembranes, single biomolecules, bacteria and viruses) at the nanoscale.