Microscale Bipolar Charge Distributions on Surfaces after Liquid Wetting and Evaporation in an Electric Field

Studies have shown that when insulator surfaces become electrostatically charged, complex spatial distributions of charge are produced, which are made up of micrometer-scale regions of both charge polarities. The origin of these charge patterns, often called charge mosaics, is not understood. Here, we carried out controlled Kelvin force microscopy experiments on microfabricated interdigitated electrode systems to show that the process of wetting a surface by a liquid followed by evaporation of the liquid in an electric field can lead to neighboring micrometer-scale regions of positive and negative charge, which remain stable long after the electric field is removed. We thus suggest that local electric fields, perhaps due to the existing charge on the surface, can act in concert with liquid evaporation to contribute to the creation of charge mosaics.

Automated summary

Studies have shown that complex spatial distributions of charge, consisting of micrometer-scale regions of both positive and negative charge, are produced on insulator surfaces when they become electrostatically charged. Controlled Kelvin force microscopy experiments on microfabricated interdigitated electrode systems demonstrate that wetting a surface by a liquid followed by evaporation in an electric field can lead to neighboring micrometer-scale regions of opposite charge polarities, which remain stable long after the electric field is removed. Local electric fields, possibly due to existing charge on the surface, are suggested to act in conjunction with liquid evaporation to contribute to the creation of charge mosaics.