Remote applications of electric potential sensors in electrically unshielded environments

The electric potential sensor is a novel, ultra high impedance sensor, previously developed at the University of Sussex. These sensors have been applied to a range of applications, including electrophysiology, non destructive testing of composite materials and novel nuclear magnetic resonance NMR probes. Some of these measurements can be made in a strongly coupled (=100pF) mode, where the coupling capacitance is reasonably large and well dened, and ambient noise is therefore less problematic. However for many applications, there exists a requirement for this coupling to be much weaker. This weak and poorly dened coupling creates substantial problems with ambient noise often causing sensors to saturate and become unusable. In the past, therefore, these measurements have all been made inside electrically screened rooms and enclosures. The work discussed in this thesis explores the possibility of operating these sensors outside of electrically screened environments. A number of techniques for resilience against noise are explored and experiments to fully analyse and characterise the performance of the sensors are discussed. As a result of this work, further results are then shown for a number of experiments carried out in a busy lab environment, in the presence of noise sources, and with little or minimal screening used. In this case, data is shown for the collection of remote cardiac and respiratory data, imaging of the spatial distribution of charge on insulating materials, detecting electric eld disturbances for movement sensing and early results for a microscopic XY scanning application.