Hi all I am looking to measure minute changes in electric field strength. I found this article http://www.physorg.com/news74876394.html" [Broken] which describes how scientists at harvard isolated a single electron in a highly evacuated, absolute zero chilled chamber and manipulated its movement using electrodes. I have been thinking about doing something similar to solve the problem of measuring such tiny changes in electric field. I would like to create an electron trap, cost effectively. I basically need a FIXED amount of charge in the form of a "ball of electrons" or a "ring of electrons". I then want to control the movement of the electrons using electrodes like the scientist did. Does any one have any ideas of how to do this cost effectively. Any one got any other ideas how to measure these minute changes in electric field strength?