Apparatus for infusing liquid to a body

An infusion device having a housing with a reusable control portion and an expendable reservoir portion includes a precise drive for an infusion pump. The drive includes a piezoelectric bender assembly, a limiter and at least one contact stop. The piezoelectric bender assembly includes a cantilevered piezoelectric bender having an member of predetermined thickness fixed to move with the second end. A limiter of dimensionally stable material including a gap and at least a first mounting hole extending to the gap. The member of predetermined thickness extends into the gap. A first contact stop is positioned in the gap to define a critical gap distance limiting movement of the member of predetermined thickness in the gap. A base has a mounting surface, a port through the base and extending to the mounting surface. The port includes a first length having a smaller diameter at the mounting surface and a second length displaced from the mounting surface and having a larger diameter. A rigid cannula extends from the base through the port. The rigid cannula has a diameter smaller than the smaller diameter of the port, and the first length of the port has an annular open gap for lateral or pivotal movement of the rigid cannula. A mount of elastomeric material in the length having the larger diameter mounts the rigid cannula. The cannula includes hydrogel material in a desiccated state coating the surface of the cannula, including the beveled end, which rehydrates upon placement in the patient.