{TAIL ~ The method} 7, further comprising sequentially energizing {HEAD ~ the electrodes} to create a traveling wave 
to create
{ TAIL ~ The method } 7 , further comprising sequentially energizing { HEAD ~ the electrodes } to create a traveling wave
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH