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