Shape Memory Alloy Insulin Pump Actuation
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Solution Overview
Problem
Current insulin pumps are expensive, complex, and heavy due to their reliance on precision stepper motors, making them costly and difficult to maintain, while alternative shape memory alloy actuators lack precision and repeatability.
Innovation Solution
A cost-effective pumping system using a shape memory alloy actuator with an intelligent control system that provides precise, reliable, and fault-tolerant insulin delivery, allowing for disposable usage while maintaining precision and minimizing stress on the pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a precision stepper motor and lead screw mechanism are used to achieve precise insulin delivery, then delivery precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical stepper motor and lead screw system with a shape memory alloy (SMA) actuator that uses thermal-mechanical coupling to drive the plunger. The SMA wire converts electrical energy to thermal energy through resistive heating, which then induces mechanical contraction to move the plunger, eliminating complex mechanical transmission components while maintaining precise delivery control through electrical pulse management.
Solution Approach 2:
The patent controls insulin delivery precision by changing the thermal parameters of the shape memory alloy actuator. By adjusting the duration, amplitude, and frequency of electrical pulses applied to the SMA wire, the system precisely controls the temperature变化 and corresponding mechanical contraction of the alloy, thereby regulating the plunger displacement and insulin delivery rate without mechanical feedback mechanisms.
2Reliability
If a precision stepper motor is used to ensure reliable insulin delivery, then delivery reliability is improved, but device weight increases
Solution Approach 1:
The patent eliminates heavy mechanical components (stepper motor, lead screw, gears) by substituting them with a lightweight shape memory alloy wire actuator. The SMA-based actuation system reduces the moving mass significantly while maintaining reliable insulin delivery through the inherent repeatability of the shape memory effect and controlled thermal cycles.
3Device complexity
If a shape memory alloy actuator is used to reduce cost and weight, then device cost and weight are reduced, but delivery precision and repeatability deteriorate
Solution Approach 1:
The patent incorporates a feedback control system that monitors the actual insulin delivery and compares it with the target delivery profile. The system uses this feedback information to adjust the electrical pulse parameters (duration, amplitude, frequency) applied to the shape memory alloy actuator in real-time, compensating for variations in SMA material properties, thermal environment, and mechanical friction to maintain precise and repeatable delivery.
Solution Approach 2:
The patent employs periodic electrical pulsing of the shape memory alloy actuator to achieve precise plunger positioning. By using controlled thermal cycling through periodic heating and cooling phases, the system exploits the reversible shape memory effect to create repeatable mechanical motion cycles, enhancing delivery precision through the inherent reversibility and consistency of the phase transformation in the SMA material.
4Ease of manufacture
If a shape memory alloy actuator is used to enable disposable usage, then ease of disposal is improved, but stress on the pump increases
Solution Approach 1:
The patent designs the pump system with built-in stress mitigation features before deployment. The control algorithm incorporates stress-aware pulse patterns that prevent excessive thermal and mechanical loading on the shape memory alloy actuator and other pump components. By anticipating stress accumulation during repeated actuation cycles, the system adjusts operating parameters to stay within safe stress thresholds, enabling reliable disposable usage without component failure.
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 precise and reliable insulin delivery, reduces the overall weight and size of the pump, and extends its lifespan by minimizing stress and enabling operation even under fault conditions, making it suitable for frequent replacement.
Implementation Method 1
Shape memory alloys are a part of a class of materials that change shape when power is applied to them but that return to their natural state when the power is removed.
Implementation Method 2
The materials can be used to form an actuator by harnessing this unique attribute of the materials.
Data Source
AI summary
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.