said membrane having formed therein a pleated structure surrounding said contact region and defining a bellows portion for increasing {HEAD ~ a displacement distance} of {TAIL ~ said contact region} of said membrane 
of
said membrane having formed therein a pleated structure surrounding said contact region and defining a bellows portion for increasing { HEAD ~ a displacement distance } of { TAIL ~ said contact region } of said membrane
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH