{HEAD ~ Small perturbations} in the drive voltage are applied at a level to cause a measurable variation in {TAIL ~ the sensor output current} 
{ HEAD ~ Small perturbations } in the drive voltage are applied at a level to cause a measurable variation in { TAIL ~ the sensor output current }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL