It looks like they use a single band looped over a rod.  It appears to be very similar to a Van De Graaff generator.<p><a href="http:&#x2F;&#x2F;tribogenics.com&#x2F;wp-content&#x2F;uploads&#x2F;2015&#x2F;08&#x2F;Eli-Paper-.pdf" rel="nofollow">http:&#x2F;&#x2F;tribogenics.com&#x2F;wp-content&#x2F;uploads&#x2F;2015&#x2F;08&#x2F;Eli-Paper-...</a>