Non-contact Measurement of DC Potentials with Applications in Static Charge Imaging

A non-contact capacitive DC voltage probing technique capable of measuring potential differences as low as 30 mV with a 1.5% accuracy is presented. The technique relies on measuring the voltage induced on a sensing conductor as result of moving it in the gradient of an electric field. This sensor achieved a sensitivity up to 197 mV s V−1. The influence of speed and separation between the sensing electrode and the source terminals are also investigated. In addition to empirical analysis, a physical model is developed to calibrate and describe the measurement technique mathematically. Due to the capacitive nature of the technique, the terminals of the voltage source under test can be either exposed to the sensing element or insulated. As well as non-contact measurements of DC potentials, this technique can be used to image the electrostatic charge distribution on insulating materials. An immediate application to this is the non-destructive imaging of latent fingerprints on insulating surfaces due to contact electrification. The presented technique is envisioned for applications such as battery production and quality monitoring, IC design and diagnostics, as well as forensic sciences.