Variable volume, shape memory actuated insulin dispensing pump
First Claim
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1. A method of pumping a liquid, comprising:
- applying at least one electrical pulse to a shape memory alloy to overcome a bias force of a first spring coupled to the shape memory alloy to move a piston from a first position of a pumping cycle to a second position of the pumping cycle such that a liquid is drawn into a chamber when the piston is moved from the first position to the second position and expelled from the chamber when the piston is moved from the second position to the first position;
detecting a stressed state of the shape memory alloy resulting from the shape memory alloy overcoming a bias force of a second spring coupled to the shape memory alloy;
detecting an occlusion by monitoring an amount of time required to move the piston from the first position to the second position using an encoding grid disposed on the piston and comparing the amount of time to move the piston from the first position to the second position to a first predetermined time period; and
modifying the at least one electrical pulse when at least one of the stressed state is detected or the occlusion is detected.
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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.
1012 Citations
26 Claims
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1. A method of pumping a liquid, comprising:
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applying at least one electrical pulse to a shape memory alloy to overcome a bias force of a first spring coupled to the shape memory alloy to move a piston from a first position of a pumping cycle to a second position of the pumping cycle such that a liquid is drawn into a chamber when the piston is moved from the first position to the second position and expelled from the chamber when the piston is moved from the second position to the first position; detecting a stressed state of the shape memory alloy resulting from the shape memory alloy overcoming a bias force of a second spring coupled to the shape memory alloy; detecting an occlusion by monitoring an amount of time required to move the piston from the first position to the second position using an encoding grid disposed on the piston and comparing the amount of time to move the piston from the first position to the second position to a first predetermined time period; and modifying the at least one electrical pulse when at least one of the stressed state is detected or the occlusion is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus, comprising:
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a pump component; a microprocessor; and a drive circuit operatively coupled to the microprocessor and the pump component, the drive circuit including a shape memory alloy operatively coupled to the pump component and configured to move the pump component from a first position of a pumping cycle to a second position of the pumping cycle such that a liquid is drawn into a chamber when the pump component is moved from the first position to the second position and expelled from the chamber when the pump component is moved from the second position to the first position, the drive circuit further including a first spring coupled to the shape memory alloy and the pump component, and a second spring coupled to the shape memory alloy; wherein the microprocessor is programmed to; control the drive circuit to apply at least one electrical pulse to the shape memory alloy to overcome a bias force of the first spring to move the pump component from the first position to the second position; detect a stressed state of the shape memory alloy resulting from the shape memory alloy overcoming a bias force of the second spring; detect an occlusion by monitoring an amount of time required to move the pump component from the first position to the second position using an encoding grid disposed on the pump component and comparing the monitored amount of time to move the pump component from the first position to the second position to a first predetermined time period; and modify the at least one electrical pulse when at least one of the stressed state or the occlusion is detected. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification