Device and method employing shape memory alloy
First Claim
1. A medical device for pumping a fluid, comprising:
- a plunger having a shaft sized for slidable movement through a rigid restraint;
a piston attached to the plunger shaft and configured for reciprocal movement in a displacement cavity between a first projection and a second projection extending outwardly from a cavity wall;
an inlet conduit spaced apart from the piston and in fluid communication with the displacement cavity;
a shape memory alloy wire attached to the plunger for pulling the plunger in a first direction relative to the displacement cavity;
a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and
an insulin reservoir containing insulin and being in fluid communication with the displacement cavity via the inlet conduit so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity.
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Accused Products
Abstract
A system for the metering and delivery of small discrete volumes of liquid is comprised of a small or minimal number of inexpensive components. One such component is a movable member, such as a miniature precision reciprocating displacement pump head, which is driven by an actuator that comprises a shape memory alloy material. The operating mechanism of the system is of little or minimal complexity. The system facilitates the precise metering and delivery of the small discrete volumes of liquid. Potential applications for the system include subcutaneous, long-term, automated drug delivery, for example, the delivery of insulin to a person with diabetes. In such an application, the small, simple and inexpensive nature of the invention would allow for its use as both a portable and a disposable system.
88 Citations
69 Claims
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1. A medical device for pumping a fluid, comprising:
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a plunger having a shaft sized for slidable movement through a rigid restraint; a piston attached to the plunger shaft and configured for reciprocal movement in a displacement cavity between a first projection and a second projection extending outwardly from a cavity wall; an inlet conduit spaced apart from the piston and in fluid communication with the displacement cavity; a shape memory alloy wire attached to the plunger for pulling the plunger in a first direction relative to the displacement cavity; a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and an insulin reservoir containing insulin and being in fluid communication with the displacement cavity via the inlet conduit so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A medical device for pumping a fluid, comprising:
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a plunger having a shaft sized for slidable movement in a restraint; a piston attached to the plunger and configured for reciprocal movement in a tubular-shaped displacement cavity between a first projection and a second projection extending outwardly from a cavity wall; an inlet conduit spaced apart from the piston and in fluid communication with the displacement cavity; a shape memory alloy wire attached to the plunger for moving the plunger in a first direction relative to the displacement cavity; a digital timing circuit for activating the shape memory alloy wire including a capacitor for providing electrical energy to the shape memory alloy wire; and an insulin reservoir containing insulin and being in fluid communication with the displacement cavity via the inlet conduit so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the tubular-shaped displacement cavity. - View Dependent Claims (28, 29, 30, 31, 32)
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33. An insulin pump, comprising:
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a plunger having a shaft sized for slidable movement in a rigid restraint; a piston attached to the plunger and configured for reciprocal movement in a displacement cavity between a first projection and a second projection extending outwardly from a cavity wall; an inlet conduit spaced apart from the piston and in fluid communication with the displacement cavity; a shape memory alloy wire attached to the plunger for pulling the plunger in a first direction relative to the displacement cavity; a digital timing circuit for activating the shape memory alloy wire including a battery for providing electrical energy to the shape memory alloy wire; and an insulin reservoir containing insulin and being in fluid communication with the displacement cavity via the inlet conduit so that as the shape memory alloy wire is activated the wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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56. An insulin pump, comprising:
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a plunger attached to a piston and configured for restrained reciprocal movement in a displacement cavity between a first projection and a second projection extending outwardly from a cavity wall; an inlet conduit spaced apart from the piston and in fluid communication with the displacement cavity; a single length of shape memory alloy wire attached to the plunger for pulling the plunger in a first direction in the displacement cavity; a digital timing circuit for activating the shape memory alloy wire including a power source for providing electrical energy to the shape memory alloy wire; an insulin reservoir containing insulin and being in fluid communication with the displacement cavity via the inlet conduit so that as the shape memory alloy wire is activated the single length of wire shortens and pulls the plunger in the first direction thereby drawing a predetermined volume of insulin from the reservoir into the displacement cavity; and cooling the shape memory alloy wire so that a biasing spring associated with the plunger lengthens the wire and moves the plunger to the second projection corresponding to the minimum volume within the displacement cavity. - View Dependent Claims (57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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Specification