Variable volume, shape memory actuated insulin dispensing pump
First Claim
Patent Images
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 element, the element moving the piston between a first and second physical limit, such that when the piston is at the first limit the chamber is occupied with liquid and when the chamber is at the second limit the chamber is substantially discharged of liquid; and
a first switch at the first limit that indicates if the piston is at the first limit.
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Abstract
A portable pumping system provides insulin or other drugs to a user. A shape memory element is used to actuate the pump and an intelligent system controls the actuator in order to minimize stresses within the system and provide accurate and reliable dosage delivery. The control system utilizes various types of feedback to monitor and optimize the position of the pumping mechanisms. Physical design aspects also minimize stress and the combination of the physical design aspects and the intelligent operation of the system results in a lightweight and cost effective pump that may be used in a disposable fashion if desired.
250 Citations
27 Claims
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1. A pumping system comprising:
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a chamber;
a piston within the chamber;
a shape memory element within the chamber that changes length when a current flows through the element, the element moving the piston between a first and second physical limit, such that when the piston is at the first limit the chamber is occupied with liquid and when the chamber is at the second limit the chamber is substantially discharged of liquid; and
a first switch at the first limit that indicates if the piston is at the first limit. - View Dependent Claims (2, 3, 4)
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5. A method of dispensing a liquid, comprising:
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drawing liquid into a pumping chamber by causing a shape memory material to contract and move a piston;
expelling liquid from the pumping chamber by causing the shape memory material to relax and move the piston;
monitoring the position of the piston; and
controlling the position of the piston based upon the monitored position. - View Dependent Claims (6, 7, 8, 9)
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10. A hydraulic pump comprising:
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a chamber;
a piston within the chamber;
a shape memory element that drives the piston;
a stroke length equal to the maximum distance of travel of a pumping surface of the piston;
a position sensing mechanism that senses the position of the piston; and
a positioning system including a linear feedback mechanism, wherein the positioning system moves the piston in increments less than the stroke length, resulting in a partial piston stroke. - View Dependent Claims (11, 12, 13, 14)
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15. A pump comprising:
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a reservoir having a maximum volume;
an actuator comprising a shape memory alloy that moves a plunger, the plunger displacing liquid from the reservoir; and
a control system that utilizes linear feedback to sense the position of the actuator and to manipulate the actuator to provide doses of variable volumes less than the maximum volume. - View Dependent Claims (16, 17, 18, 19)
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20. A pump comprising:
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a shape memory alloy;
a piston connected to the shape memory alloy, said piston having a stroke length;
means for sensing the precise position of the piston at any point of the piston stroke; and
means for controlling the position of the piston by changing the length of the shape memory alloy, said means for controlling able to position the piston at any point of the piston stroke thereby enabling the pump to pump variable dosage sizes of a liquid.
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21. A method of dispensing a liquid, comprising:
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providing a piston connected to a shape memory element;
providing a potential to the shape memory element in order to change the length of the element, monitoring the position of the piston; and
adjusting the potential applied to the shape memory element to move the piston and dispense liquid, based upon the monitored position. - View Dependent Claims (22, 23, 24)
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25. A method of pumping a liquid, comprising:
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applying at least one electrical pulse to a shape memory alloy to move a piston;
detecting a stressed state of the shape memory alloy; and
modifying the at least one pulse if the stressed state is detected. - View Dependent Claims (26)
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27. A pumping system comprising:
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a chamber;
a first piston within the chamber;
a shape memory element within the chamber that changes length when a current flows through the element, the element moving the first piston between a first and second physical limit, such that when the first piston is at the first limit the chamber is occupied with liquid and when the chamber is at the second limit the chamber is substantially discharged of liquid; and
a second piston coupled to the shape memory element that moves to accommodate changes in the shape memory element and reduce stress on the pumping system.
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Specification