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