{TAIL ~ The current} is then measured between the electrodes at {HEAD ~ the plurality} of voltages and a contamination level is determined using the measured currents 
{ TAIL ~ The current } is then measured between the electrodes at { HEAD ~ the plurality } of voltages and a contamination level is determined using the measured currents
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH