A feedback control system for an electrospray nozzle and counter-electrode, comprising a source of light which intersects, one or snore of the liquid cone, jet and plume of the fluid exiting the nozzle, one or more photo detectors to detect light patterns and generate photo-electronic signals in response...http://www.google.com/patents/US6744046?utm_source=gb-gplus-sharePatent US6744046 - Method and apparatus for feedback controlled electrospray
