SMA-Actuated Intermediate Pumping Chamber for Precise Drug Dosing
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Solution Overview
Problem
Conventional drug delivery devices often result in under- or over-delivery of liquid drug doses due to mechanical sticking or slipping of the pump mechanism, and there is a need for a simplified system that accurately expels a fixed volume of liquid drug while reducing the device size.
Innovation Solution
A wearable drug delivery device with a chamber body, a sliding fluidic member, and a shape memory alloy wire that draws and expels liquid drug into a needle, using a plunger channel and a hard stop to ensure precise dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional plunger-based pump mechanism is used, then the device can deliver liquid drug, but mechanical sticking or slipping occurs resulting in under- or over-delivery of doses
Solution Approach 1:
The patent replaces the conventional mechanical plunger-based pump mechanism with a shape memory alloy (SMA) wire-driven system. The SMA wire undergoes phase transformation under electrical stimulation to generate linear motion, eliminating complex mechanical components like plungers, seals, and valves that are prone to sticking or slipping. This substitution of mechanical actuation with smart material actuation directly addresses the reliability issue while simplifying the overall mechanism.
Solution Approach 2:
The patent utilizes the phase transformation properties of shape memory alloy wire, which changes its physical state (from austenite to martensite phase) in response to electrical stimulation. This parameter change in the material's crystalline structure enables controlled linear contraction and expansion, providing precise dose delivery without the mechanical errors associated with conventional pump mechanisms.
2Reliability
If a conventional plunger-based pump mechanism is used, then the device can deliver liquid drug, but the overall device size increases
Solution Approach 1:
The SMA wire-driven intermediate pumping chamber replaces the bulky conventional plunger mechanism, significantly reducing the volume required for the pumping function. The smart material actuation system requires minimal space compared to traditional mechanical components, enabling a more compact overall device design while maintaining reliable dose delivery accuracy.
Solution Approach 2:
The patent employs a nested configuration where the sliding fluidic member is positioned within the intermediate pumping chamber, and the SMA wire is integrated within the fluidic member structure. This nesting arrangement maximizes space utilization and minimizes the overall device volume while ensuring accurate dose delivery through the compact integrated system.
3Volume of moving object
If a simplified pump system is used to reduce device size, then the device size decreases, but mechanical sticking or slipping errors increase
Solution Approach 1:
The patent resolves this contradiction by replacing the simplified but error-prone mechanical system with an SMA wire-driven system that combines both compact size and high reliability. The direct linear actuation of the SMA wire eliminates intermediate mechanical linkages that could stick or slip, achieving accurate dose delivery in a compact form factor.
Solution Approach 2:
The shape memory alloy wire provides self-contained actuation through its inherent phase transformation properties when stimulated electrically. The material itself generates the mechanical motion required for pumping without requiring additional mechanical components, seals, or valves that could fail. This self-service capability ensures reliable dose delivery while maintaining a simplified compact structure.
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 accurately expels a set amount of liquid drug per pulse, reducing mechanical errors and device size, and operates as a closed-loop or hybrid system for controlled drug delivery.
Implementation Method 1
a shape memory alloy wire coupled to the sliding fluidic member. The shape memory alloy wire is operable to draw the liquid drug from the reservoir through the inlet port and into the pump chamber by pulling the sliding fluidic member and the plunger in a first direction
Data Source
AI summary
Disclosed are examples of devices, systems and techniques for delivering a liquid drug. An example delivery pump device may include a chamber body defining a pump chamber, an inlet valve to receive a liquid drug and a hard stop. A plunger configured with a plunger channel. A sliding fluidic member including a needle coupling, a flow orifice, a face seal and an anchor portion that may be movable within the pump chamber. A pump mechanism may be coupled to the anchor portion and operable to pull the anchor portion and the plunger toward the hard stop. Techniques may include determining a time to output a liquid drug from the delivery pump device; generating a control signal to actuate the delivery pump device; applying a control signal to the pump mechanism; determining that a control signal is to be removed from the pump mechanism; and delivering the liquid drug.