Shape-Memory Alloy Wire Control for Precise Infusion Pumping
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Solution Overview
Problem
Existing portable and wearable fluid delivery devices for therapeutics, such as infusion pumps, face challenges including high malfunction rates, size, weight, and cost issues, as well as difficulties in maintaining consistent drug administration schedules and skin application.
Innovation Solution
A wearable infusion pump assembly utilizing a shape-memory alloy wire actuation system that adjusts pumping time based on temperature and volume measurements, incorporating a controller, temperature sensor, and volume sensor to ensure precise fluid delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If shape-memory alloy wire is used for pump actuation, then device size and weight are reduced, but temperature sensitivity causes malfunction
Solution Approach 1:
The system incorporates a temperature sensor that continuously monitors the temperature of the shape-memory alloy wire and feeds this information back to the controller. The controller adjusts the pump actuation timing based on the measured temperature, compensating for temperature-induced variations in the wire's actuation characteristics and ensuring reliable operation across different temperature conditions.
Solution Approach 2:
The system dynamically changes the actuation parameters (specifically the pump activation timing) based on the measured temperature of the shape-memory alloy wire. By adjusting the timing parameter in response to temperature variations, the system maintains consistent pump performance despite changes in the wire's thermal state.
2Device complexity
If shape-memory alloy wire actuation is used, then device complexity is reduced, but temperature compensation is required for precision
Solution Approach 1:
The system uses temperature feedback from the shape-memory alloy wire to adjust pump actuation timing. This feedback mechanism enables precise control of fluid delivery by compensating for temperature effects on the actuator, maintaining measurement precision without adding significant system complexity.
Solution Approach 2:
The system replaces complex mechanical timing mechanisms with a temperature-based control system. Instead of using mechanical clocks or timers, the system uses temperature sensing and electronic timing control to achieve precise pump actuation, simplifying the overall device while maintaining precision.
3Reliability
If temperature-based timing adjustment is implemented, then actuation reliability improves, but device complexity increases
Solution Approach 1:
The system implements a temperature feedback loop where the temperature sensor monitors the shape-memory alloy wire temperature and the controller adjusts actuation timing accordingly. This feedback approach improves reliability by adapting to temperature changes while keeping the control logic relatively simple and direct.
Solution Approach 2:
The system uses the temperature information from the shape-memory alloy wire environment to self-adjust its actuation timing. The controller automatically compensates for temperature effects without requiring external calibration or complex intervention, allowing the system to self-regulate based on its operating conditions.
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 enhances the reliability and accuracy of fluid delivery, reduces device size and weight, and improves user convenience by automatically adjusting for temperature-induced changes in the shape-memory alloy wire, thereby maintaining consistent therapeutic dosing.
Implementation Method 1
a pump plunger (106) and at least one shape-memory alloy wire (112) operably connected to the pump plunger (106), wherein the shape-memory alloy wire (112), when actuated, actuates the pump plunger (106)
Implementation Method 2
a controller (110) for controlling an ontime of the at least one shape-memory alloy wire (112), wherein the controller (110) determines the ontime based on a temperature of the shape-memory alloy wire (112)
Data Source
AI summary
A method for controlling a device using a shape-memory alloy wire is disclosed. The method includes determining an ontime for the shape-memory alloy wire based on a target volume to be pumped by a pump plunger, determining the temperature of the shape-memory alloy wire and adjusting the ontime based on the temperature of the shape-memory alloy wire.