SMA Pump Actuation Control Using Resistance-Based Pulse Termination
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Solution Overview
Problem
Conventional medicament delivery devices relying on shape memory alloy (SMA) elements for actuation face inefficiencies in terminating the electric pulse, leading to increased energy consumption and mechanical fatigue, as they rely on mechanical mechanisms rather than real-time resistance monitoring for pulse termination.
Innovation Solution
A medicament delivery device equipped with a processor that monitors resistance values, rate of change, and temperature of the SMA element to determine the optimal time to terminate the electric pulse, reducing energy usage and extending the lifespan of the device by using more accurate and earlier termination of the pulse application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical termination mechanism relying on overshoot is used to terminate the electric pulse, then the device structure is simple, but energy consumption increases and mechanical fatigue occurs
Solution Approach 1:
The patent replaces the mechanical termination mechanism (which relies on physical overshoot and contact) with an electrical monitoring system that measures resistance changes in the SMA element. The processor detects when the resistance change rate falls below a threshold, indicating the phase transition is complete, and terminates the pulse electrically without mechanical contact. This substitution eliminates the need for mechanical components while reducing energy consumption and mechanical fatigue.
Solution Approach 2:
The patent implements a feedback control system where the processor continuously monitors the resistance of the SMA element during heating, calculates the rate of change, and uses this feedback information to determine the optimal termination point. When the resistance change rate drops below a predetermined threshold, the system terminates the electric pulse, creating a closed-loop control that optimizes energy usage and prevents overheating.
2Device complexity
If a mechanical termination mechanism relying on overshoot is used to terminate the electric pulse, then the device structure is simple, but the lifespan of the device decreases due to mechanical fatigue
Solution Approach 1:
The patent replaces the mechanical termination mechanism (which relies on physical overshoot and contact) with an electrical monitoring system that measures resistance changes in the SMA element. The processor detects when the resistance change rate falls below a threshold, indicating the phase transition is complete, and terminates the pulse electrically without mechanical contact. This substitution eliminates the need for mechanical components while reducing energy consumption and mechanical fatigue.
Solution Approach 2:
The SMA element itself provides the termination signal through its own resistance characteristics. As the SMA element undergoes phase transition, its resistance changes naturally, and this intrinsic property is used by the processor to determine when to terminate the pulse. The system uses the element's own physical properties for self-monitoring and self-termination, eliminating the need for external mechanical termination components that cause fatigue.
3Loss of energy
If real-time resistance monitoring is used to determine pulse termination, then energy consumption is reduced, but device complexity increases
Solution Approach 1:
The processor in the system performs multiple functions: it controls the electric pulse output, monitors the resistance of the SMA element in real-time, calculates the rate of change of resistance, compares it against thresholds, and terminates the pulse when conditions are met. By making the processor multi-functional, the patent avoids adding separate dedicated hardware for each function, thereby managing complexity while achieving energy efficiency through intelligent control.
Solution Approach 2:
The patent replaces the mechanical termination mechanism (which relies on physical overshoot and contact) with an electrical monitoring system that measures resistance changes in the SMA element. The processor detects when the resistance change rate falls below a threshold, indicating the phase transition is complete, and terminates the pulse electrically without mechanical contact. This substitution eliminates the need for mechanical components while reducing energy consumption and mechanical fatigue.
4Reliability
If real-time resistance monitoring is used to determine pulse termination, then mechanical fatigue is reduced, but device complexity increases
Solution Approach 1:
The patent implements a feedback control system where the processor continuously monitors the resistance of the SMA element during heating, calculates the rate of change, and uses this feedback information to determine the optimal termination point. When the resistance change rate drops below a predetermined threshold, the system terminates the electric pulse, creating a closed-loop control that optimizes energy usage and prevents overheating.
Solution Approach 2:
The patent replaces the mechanical termination mechanism (which relies on physical overshoot and contact) with an electrical monitoring system that measures resistance changes in the SMA element. The processor detects when the resistance change rate falls below a threshold, indicating the phase transition is complete, and terminates the pulse electrically without mechanical contact. This substitution eliminates the need for mechanical components while reducing energy consumption and mechanical fatigue.
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
This approach results in lower energy consumption and reduced mechanical fatigue of the SMA elements, extending the device's operational time and maintaining the integrity of the components by using real-time resistance monitoring for precise pulse termination.
Implementation Method 1
SMA elements transition between shapes as the temperatures of the elements change. SMA elements 'remember' their original shapes when the temperature of the elements reaches a transition temperature.
Implementation Method 2
an electric pulse of a predetermined duration is applied to the SMA wire in the device. The application of the electric pulse causes the SMA wire to heat and shorten.
Data Source
AI summary
Exemplary embodiments may terminate application of an electric pulse to a shape memory alloy (SMA) element that causes actuation of a medicament pump based on resistance values unlike conventional approaches that rely on a mechanical mechanisms to trigger termination of the application of the electric pulse. The magnitude of the resistance values, the rate of change (RoC) of the resistance values, the temperature of the SMA element, the time that has passed since initial application of the electric pulse to the SMA element, or combinations thereof may be used to trigger the termination of the application of the electric pulse to the SMA element in exemplary embodiments. The monitoring of the resistance of an unactuated SMA element may be used to determine when to initiate and when to terminate application of an electrical pulse to the other SMA element.