SMA Auto-Injector Actuator for Consistent Medicament Delivery
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Solution Overview
Problem
Existing auto-injector devices lack an efficient mechanism for reliably and comfortably delivering medicaments, particularly in terms of temperature-controlled delivery and user comfort, as they often rely on mechanical springs that may not provide consistent performance across varying medicament viscosities and temperatures.
Innovation Solution
An auto-injector device utilizing a shape memory alloy (SMA) driving element that changes configuration with temperature, combined with a chemical heating mechanism or fluid heating system, to actively drive the medicament expulsion, ensuring consistent delivery and warming of the medicament to body temperature for enhanced user comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical springs are used to drive medicament expulsion, then the device structure is simple, but the performance is inconsistent across varying medicament viscosities and temperatures
Solution Approach 1:
The patent replaces traditional mechanical spring systems with a shape memory alloy (SMA) actuator that responds to thermal stimuli. The SMA element undergoes a phase transformation when heated, causing it to contract and drive the plunger forward. This substitution of mechanical actuation with thermally-driven shape memory material provides more consistent performance across varying medicament viscosities and temperatures, as the SMA's phase transformation provides a more reliable and controllable driving force.
Solution Approach 2:
The patent utilizes changes in temperature as a control parameter to activate the shape memory alloy actuator. By heating the SMA element to its transformation temperature, the material undergoes a reversible phase change that alters its shape and dimensions, thereby driving the medicament expulsion. This parameter-based control allows for consistent performance by precisely controlling the actuation temperature and timing.
2Ease of operation
If traditional mechanical drive mechanisms are used, then the device is simpler to manufacture, but user comfort is reduced due to lack of temperature control
Solution Approach 1:
The patent replaces simple mechanical drive mechanisms with a thermally-actuated shape memory alloy system. The SMA actuator, when heated to its transformation temperature, contracts and drives the plunger, providing both medicament expulsion and simultaneous warming of the medicament to body temperature. This dual function enhances user comfort by eliminating the discomfort of cold injections while the modular SMA component design maintains reasonable manufacturing complexity.
Solution Approach 2:
The patent exploits the phase transition properties of shape memory alloys to achieve both medicament delivery and temperature control. The SMA material transitions from a martensite phase (at lower temperatures) to an austenite phase (at higher temperatures), with this phase change driving the actuator contraction. The same phase transition simultaneously warms the medicament, providing user comfort benefits without requiring separate heating mechanisms.
3Reliability
If shape memory alloy with heating mechanism is used, then medicament delivery consistency is improved, but device complexity increases
Solution Approach 1:
The patent merges the heating function and the actuation function into a single integrated system. The shape memory alloy actuator serves dual purposes: it is heated to trigger its phase transformation for driving the plunger, and the same heating process simultaneously warms the medicament to body temperature. This merging of functions eliminates the need for separate heating mechanisms, reducing overall device complexity while maintaining delivery consistency through precise thermal control of the SMA element.
Solution Approach 2:
The shape memory alloy heating mechanism serves multiple functions within the device: (1) it acts as the actuator driver through thermal expansion and phase transformation, (2) it warms the medicament to body temperature for user comfort, and (3) it provides controlled, consistent delivery by precisely timing the phase transition. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity while achieving reliable delivery consistency.
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 SMA-driven auto-injector provides reliable and efficient medicament delivery, improving user comfort by warming the medicament to body temperature and ensuring consistent performance across different medicament viscosities and temperatures, while the heating mechanism enhances the dispense mechanism's efficiency and user experience.
Implementation Method 1
a driving element, formed from a shape memory alloy, which has a first configuration and a second configuration and is configured to change shape from the first configuration to the second configuration when the temperature of the driving element is raised above a shape change temperature
Implementation Method 2
a heating mechanism configured to actively heat the driving element, wherein the heating mechanism is a chemical heating element configured to generate heat through an exothermic process
Implementation Method 3
a heater configured to heat the fluid in the fluid reservoir
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
An auto-injector device (100) comprises a medicament reservoir, a stopper (14) for expelling a medicament out of the medicament reservoir (18); a driving element (130), formed from a shape memory alloy, which has a first configuration and a second configuration and i configured to change shape from the first configuration to the second configuration when the temperature of the driving element is raised above a shape change temperature, so as to drive the stopper of the syringe mechanism through the medicament reservoir; and a heating mechanism configured to actively heat the driving element. The heating mechanism is a chemical heating element configured to generate heat through an exothermic process or comprises a fluid reservoir for retaining a fluid; a heater configured to heat the fluid in the fluid reservoir; a pump configured to expel the fluid out of the fluid reservoir; and a connecting conduit arranged to carry the fluid from the fluid reservoir to the driving element.