Variable volume, shape memory actuated insulin dispensing pump

  • US 7,993,109 B2
  • Filed: 12/29/2008
  • Issued: 08/09/2011
  • Est. Priority Date: 10/09/2002
  • Status: Active Grant
First Claim
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1. A method of dispensing liquid from a pump, comprising:

  • drawing a first volume of the liquid into a pumping chamber by causing a shape memory material to contract and move a piston to a first position of a plurality of positions;

    expelling a second volume of the liquid from the pumping chamber by causing the shape memory material to relax and move the piston to a second position of the plurality of positions;

    monitoring each of the plurality of positions of the piston using an encoding grid disposed on the piston, wherein a first location on the encoding grid indicates the first position of the plurality of positions of the piston and wherein a second location on the encoding grid indicates the second position of the plurality positions of the piston; and

    measuring a first time period, wherein the first time period is the time it takes to draw the first volume of liquid into the pumping chamber;

    comparing the first time period to a predetermined time period; and

    determining that the pump is not primed when the first time period is below the predetermined time period by a threshold amount of time.

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