Variable volume, shape memory actuated insulin dispensing pump

  • US 8,047,811 B2
  • Filed: 12/29/2008
  • Issued: 11/01/2011
  • Est. Priority Date: 10/09/2002
  • Status: Active Grant
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First Claim
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1. A pumping system comprising:

  • a chamber;

    a piston within the chamber;

    a shape memory element within the chamber that changes length when a current flows through the shape memory element,the shape memory element moving the piston between a first physical limit at a proximal end of the chamber and second physical limit at a distal end of the chamber, such that when the piston is at the first physical limit the chamber is filled with fluid and when the piston is at the second physical limit the chamber is discharged of fluid;

    a first switch at the first physical limit that indicates the piston is in contact with the first physical limit; and

    a processor programmed to measure a first time period, wherein the first time period is the time it takes for the piston to move between the proximal end and the distal end, to compare the first time period to a predetermined time period, and to determine that the pumping system is not primed when the first time period is below the predetermined time period by a threshold amount of time.

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