Heterogeneity of surface potential in contact electrification under ambient conditions: A comparison of pre- and post-contact states

• We measured the surface electric potential before and after contact electrification.
• After contact with silicone elastomer, the glass surface had heterogeneous charge.
• After contact with silicone elastomer, the gold surface was uniformly charged.
• Data show that macro-scale contact with glass can lead to micro-scale charge pattern.

We measured the pattern of charging by contact electrification, following contact between a polydimethylsiloxane (PDMS) stamp and a glass substrate with gold electrodes. We used scanning Kelvin probe microscopy to map the surface potential at the same regions before and after contact, allowing a point-by-point comparison. After contact, the mean surface potential of the glass shifted by 360 mV and micron-scale heterogeneity appeared with a magnitude of ∼100 mV. The gold electrodes showed charge transfer but no discernible heterogeneity. These results show that contact electrification causes heterogeneity of surface potential even on non-polymer surfaces such as glass under ambient conditions.