Plessey Epic Sensors For Non Contact ECG
What is the "range" of the EPIC sensor for motion sensing?

This depends on the charge on the target, the rate of motion and the local environmental conditions. It is best to think of the EPIC sensor as being characterized by its input referred noise and its gain rather than trying to describe a range. Adult humans can carry anywhere between zero and several thousand volts, depending on clothing and their surrounding environment. This can mean that a moving human target is detectable from say a metre worst case, up to several metres best case.
 Recent developments suggest that maybe it is best not to measure perturbations in the quasi DC field but to use already existing AC fields that surround us in our normal day to day life. For example 50/60 Hz signals Using changes in the detectable signal strength amongst an array (or even between a pair) of electrodes it may be possible to locate targets at a greater range and with more reproducibility.