The open end of the water swellable agent chamber contains {HEAD ~ a semipermeable membrane} and the open end of the active agent chamber contains {TAIL ~ a back diffusion} regulating outlet 
The open end of the water swellable agent chamber contains { HEAD ~ a semipermeable membrane } and the open end of the active agent chamber contains { TAIL ~ a back diffusion } regulating outlet
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH