Detecting electric field disturbances for passive through wall movement and proximity sensing

In this paper we outline the application of a novel electric field sensor technology, developed and patented at the University of Sussex, to the sensing of movement and proximity, using a technique which is generally unaffected by the presence of walls and other structures. This is achieved by monitoring electric field disturbances which occur when a large dielectric object, such as a human or animal body, is moved through the ambient electric field. These sensors detect, passively, changes in spatial potential (electric field) created by a capacitively coupled electric field. To date we have already demonstrated the potential applications of these devices, in principle, across many areas of interest, including body electrophysiology, novel nuclear magnetic resonance (NMR) probes, non destructive testing of composite materials as well as the detection of a heart beat from distances of up to 40 cm. Here we show how, with multiple sensors in a variety of spatial arrangements, it is possible to use simple signal processing and analysis in Labview to detect movement, give an indication of direction and speed as well as track position within an open environment.© 2009 SPIE