A casing holds a syringe that contains a medicine, such as insulin, which may be driven out of the syringe by a plunger into a catheter attached to a human body. The power for the plunger drive mechanism is provided by a spiral spring mounted in the casing. A clockwork movement, regulated by a step electrical...http://www.google.de/patents/US4921487?utm_source=gb-gplus-sharePatent US4921487 - External device for injecting medicine
