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