SMA Wire Shuttle Pump for Dosage Accuracy
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Solution Overview
Problem
Conventional reciprocating pumping mechanisms in drug delivery devices face challenges in achieving dosage accuracy due to precision tolerance issues in compact designs, which are difficult to meet for small-sized pumps.
Innovation Solution
A multiple pulse shuttle pump system utilizing a shape memory alloy (SMA) wire coupled to a pumping piston, with a pin disposed within a cam's inset pathway, allowing for extended stroke length and improved accuracy by sequentially activating and deactivating the SMA wire to actuate the valve between filling and dispensing states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional reciprocating pumping mechanisms are miniaturized to make the device smaller and more compact, then the device size is reduced, but precision tolerances for dosage accuracy become very difficult to meet
Solution Approach 1:
The pump operation is segmented into multiple pulses (3:1 to 5:1 reciprocating pump) where a single reservoir pressurization cycle delivers multiple doses. This segmentation allows the pump to achieve larger effective stroke length and improved dosage accuracy without increasing the physical size of the pump components.
Solution Approach 2:
The pump uses periodic action by sequentially activating and deactivating the SMA wire to create multiple pumping pulses from a single reservoir pressurization event. This periodic activation pattern enables the small pump to deliver multiple precise doses while maintaining compact dimensions.
2Ease of operation
If the valve is designed to differentiate between filling and dispensing states with three states (closed, open for filling, open for dispensing), then the valve can control fluid flow accurately, but the device complexity increases
Solution Approach 1:
The cam mechanism acts as an intermediary that automatically guides the valve shaft through the required three states (closed, open for filling, open for dispensing). This mechanical intermediary simplifies control by eliminating the need for complex electronic control systems while maintaining accurate valve positioning for different operational states.
Solution Approach 2:
The valve system is self-regulating through the cam mechanism that automatically transitions the valve between states based on the pump cycle. The valve shaft follows the cam profile to autonomously achieve the correct positioning for filling and dispensing operations without external intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves a 3:1 to 5:1 reciprocating pump operation, allowing for larger components without increasing the overall device size, and enhances volume accuracy by extending the stroke length, making it easier to meet precision tolerances for dosage accuracy.
Implementation Method 1
A multiple pulse shuttle pump system utilizing a shape memory alloy (SMA) wire coupled to a pumping piston
Data Source
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AI summary
A multiple pulse volume shuttle pump powered by a shape memory alloy (SMA) wire is disclosed. In some embodiments, a shuttle pump system may include a pump chamber, a valve operable with the pump chamber, and a wire coupled to a valve shaft of the valve for controlling a position of the valve. The shuttle pump system may further include a pin disposed within an inset pathway of a cam, wherein the pin is moveable between multiple positions of the inset pathway in response to actuation of the valve shaft.