Patent ID: 7828792

Claim:
An implantable infusion apparatus comprising: a. a rechargeable positive pressure infusate reservoir; b. an electronically controlled metering assembly receiving infusate from said reservoir, said metering assembly comprising a pair of normally closed valves and an accumulator positioned in fluid communication with each of said valves, wherein each of said valves comprises: i. a SMA wire, having two lengths; a first longer length in its relaxed state, and a second shorter length in its energized state; ii. a fluid chamber in communication with said accumulator having an actuated member having a first setting whereby fluid flow between said fluid chamber and said accumulator is allowed and a second setting whereby said fluid chamber and said accumulator are isolated, a biasing element to urge said SMA wire from its energized length to its relaxed length, such that said actuated member moves to first setting when said wire is energized and moves to said second setting when said wire is relaxed; and iii. a fluid tight barrier between said fluid chamber and said SMA wire; c. electronic means for controlling the operation of said valves, and d. an outlet in fluid communication with said metering assembly to dispense infusate to a site in a living body, when a first of said valves is open, infusate flows from said reservoir into said accumulator and when the second valve is open and said first valve is closed, infusate flows from said accumulator into said outlet, said accumulator storing and discharging predetermined volume spikes of infusate at a frequency determined by the cycling rate of said pair of valves.