I know a lot of people claim to have got workin WFCs but I have not seen one yet.
For those who are still investigating, I have come across a patent that may shine some light on what may be going on.
http://www.google.com/patents/download/13_123_024_METHODS_AND_APPARATUS_TO_CREA.pdf?id=V6XrAQAAEBAJ&output=pdf&sig=ACfU3U2AVZVLOXfDrvLrToOVthI0cuPkWA&source=gbs_overview_r&cad=0