A reservoir for a pharmacologic delivery system wherein liquid level changes are readable visually to an accuracy of within five microliters. The reservoir is formed as a spirally coiled tubular member disposed between a pair of plate members spaced apart by one or more concentric rims. The tubular member...http://www.google.es/patents/US4311050?utm_source=gb-gplus-sharePatente US4311050 - Reservoir for medicaments
