Abstract

A self-powered device is disclosed for delivering a useful agent. The device comprises (1) a housing member, (2) a variable volume chamber storing a useful agent and having a passageway for delivering the agent in the housing, and (3) a pressure generating member comprising a semipermeable polymer having a cross-linked hydrophilic polymer dispersed therein positioned between the housing and the chamber. In operation, when the device is in a fluid environment, fluid from the environment enters the housing and is imbibed by the hydrophilic polymer into the generator, causing the generator to enlarge and apply pressure against the chamber, thereby decreasing the volume of the chamber and simultaneously dispensing agent through the passageway from the device at a controlled rate over a prolonged period of time. An article of manufacture also is disclosed which consists of a pressure generating member manufactured as a film useful for making a dispensing device.