An implantable drug delivery system has a housing, a collapsible
reservoir, a microfabricated flow channel, and at least one magnet. The
collapsible reservoir is disposed in the housing. The microfabricated
flow channel is connected at one end to the collapsible reservoir and
opens at an external surface of the housing. The magnet is disposed
within the housing adjacent a membrane defining the flow channel and is
movable in response to a magnetic force to deflect the membrane into the
flow channel for inhibiting drug flow from the collapsible reservoir to
the external surface of the housing, and for pumping drug flow from the
collapsible reservoir to the external surface of the housing.