Device and Method Employing Shape Memory Alloy
First Claim
1. A device for pumping a predetermined volume of fluid, comprising:
- a displacement cavity for holding the fluid;
a fluid inlet and a fluid outlet in communication with the cavity;
a plunger engaging the cavity;
a biasing element linked to the plunger moving the plunger to a first position compressing the fluid in the cavity;
a shape memory actuator, having a high temperature phase with a remembered configuration and a low temperature phase with a malleable configuration, connected to the plunger;
a programmable pulse generating circuit providing pulsed currents to the shape memory actuator, wherein a current on state heat transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element moves the plunger to the first position, the heating and cooling defining a single actuation cycle; and
wherein each pulsed cycle delivers the predetermined volume of fluid through the fluid outlet.
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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.
100 Citations
20 Claims
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1. A device for pumping a predetermined volume of fluid, comprising:
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a displacement cavity for holding the fluid; a fluid inlet and a fluid outlet in communication with the cavity; a plunger engaging the cavity; a biasing element linked to the plunger moving the plunger to a first position compressing the fluid in the cavity; a shape memory actuator, having a high temperature phase with a remembered configuration and a low temperature phase with a malleable configuration, connected to the plunger; a programmable pulse generating circuit providing pulsed currents to the shape memory actuator, wherein a current on state heat transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element moves the plunger to the first position, the heating and cooling defining a single actuation cycle; and wherein each pulsed cycle delivers the predetermined volume of fluid through the fluid outlet. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A device for pumping a predetermined volume of fluid, comprising:
a displacement cavity holding fluid therein; inlet and outlet valves physically discrete from the cavity and in fluid communication with the cavity; a plunger acting on the cavity to compress or decompress fluid in the cavity; a biasing element acting on the plunger to bias the plunger to a first position compressing the cavity; a shape memory actuator, having a first transition temperature to a high temperature phase with a remembered configuration and a second transition temperature to a low temperature phase with a malleable configuration, linked to the plunger; a programmable pulse generating circuit providing pulsed currents to the shape memory actuator, wherein a current on state heat transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element biases the plunger to the first position, the heating and cooling defining a single actuation cycle; and wherein each pulsed cycle delivers the predetermined volume of fluid through the fluid outlet.
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8. A method for pumping a predetermined volume of medicinal fluid via periodic dosing, comprising:
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holding fluid in a displacement cavity therein; providing a plunger that compresses and decompresses fluid in the cavity; biasing the plunger to a first position compressing the cavity; providing a shape memory actuator linked to the plunger having a remembered configuration via a first transition temperature to a high temperature phase and to a malleable configuration via a second transition temperature to a low temperature phase; thermally transforming the shape memory actuator by providing a programmable pulse generating circuit producing time-spaced, pulsed currents to the shape memory actuator, wherein a current on state heat transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position decompressing the cavity, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element biases the plunger to the first position; and wherein the thermally transforming heating and cooling of the actuator define a single actuation cycle that produces periodic dosing.
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9. A system for dispensing a predetermined volume of fluid, comprising:
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a fluid reservoir contained within an enclosure, wherein the enclosure is collapsible; a displacement cavity in communication with the fluid reservoir; a plunger acting on the cavity; a housing containing at least the cavity and plunger; a biasing element acting on the plunger to translate the plunger to a first position relative to the cavity; a shape memory actuator, having a first transition temperature to a high temperature phase with a remembered configuration and a second transition temperature to a low temperature phase with a malleable configuration, linked to the plunger; an electrical source providing a current to the shape memory actuator, wherein a current on state transforms the shape memory actuator to the high temperature phase and moves the plunger against the biasing element to a second position in a direction opposite to the first position, and a current off state allows the shape memory actuator to cool to the low temperature phase so that the biasing element biases the plunger to the first position; a blood glucose monitoring device controlling the electrical source; and wherein the enclosure is disposable and detachable from the housing. - View Dependent Claims (10, 11, 12)
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13. A device for pumping a predetermined volume of insulin, comprising:
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a fluid reservoir contained within an enclosure and holding the insulin; a displacement cavity in communication with the fluid reservoir; a fluid inlet and a fluid outlet in communication with the displacement cavity; a plunger acting on the displacement cavity; a shape memory actuator, having a first transition temperature to a high temperature phase with a remembered configuration and a second transition temperature to a low temperature phase with a malleable configuration, linked to the plunger; a biasing element linked to the plunger; an electrical source providing a current to the shape memory actuator, wherein a current on state transforms the shape memory actuator to the high temperature phase and moves the plunger to a first position within the displacement cavity, and a current off state allows the shape memory actuator to cool to the low temperature phase so that a biasing element moves the plunger to the second position within the displacement cavity; and wherein the electrical source further includes a capacitor and a battery. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification