Shape memory alloy wire driven positive displacement micropump with pulsatile output

Apparatuses and methods for pumping fluid are disclosed. An exemplary apparatus is a miniature pump that includes a shape memory wire that obtains a plastic condition below a transformation temperature and has a memorized shape such that the shape memory wire produces a work stroke by returning to the memorize shape at least at the transformation temperature. A spring biased against the shape memory wire is deflected by the work stroke to deform the shape memory wire from the memorized shape below the transformation temperature. A fluid pump is coupled to the shape memory wire and driven by the biased spring and shape memory wire to produce a fluid flow. The miniature pump can be incorporated into a self-contained infusion device in the form of a compact self-adhesive patch including a fluid reservoir, control electronics and power supply that is place directly at the infusion site of a user.