Telescoping Friction-Driven Pump Chamber for Accurate Insulin Dosing
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Solution Overview
Problem
Conventional insulin pumps are cumbersome, prone to mechanical failure, have valves that leak at elevated pressures, and require large working volumes, leading to reduced dose accuracy and reliability.
Innovation Solution
A pump sub-system with a telescoping action driven by friction, featuring a housing, piston, and plug with seals, which aligns fluid chambers with ports for intake and discharge, and uses an interlock mechanism to control piston translation, minimizing direct fluid paths and exposure to high back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional lead screw and piston type pump sub-systems are used, then pumping function is achieved, but the device becomes cumbersome with large height and footprint
Solution Approach 1:
The plug is telescoped inside the piston, with the plug's outer circumference fitting within the piston's inner circumference. This nesting arrangement allows both components to occupy the same spatial envelope, dramatically reducing the overall height and footprint of the pump subsystem while maintaining the functional separation between the piston (driven by actuator) and the plug (driven by friction from piston movement).
2Reliability
If conventional pump sub-systems with multiple components are used, then pumping function is achieved, but the risk of mechanical failure increases
Solution Approach 1:
The piston and plug are merged into a single telescoping assembly where the plug is received within the piston. This integration reduces the number of separate components and interfaces that could fail independently. The friction-driven connection between the piston and plug eliminates the need for additional transmission components, simplifying the overall mechanism and reducing failure points.
Solution Approach 2:
Valves are extracted from the pump chamber, eliminating the primary source of leakage at elevated back pressures. The friction-driven telescoping mechanism inherently provides directional control without requiring separate valve components, thereby removing the reliability issue associated with conventional valve leakage.
3Reliability
If conventional valves are used to control fluid flow, then fluid direction is achieved, but leakage occurs at elevated system back pressures
Solution Approach 1:
The friction between the piston and plug, which could be considered a source of resistance or inefficiency, is converted into a beneficial mechanism for driving the plug. The friction force directly translates piston movement into plug movement, providing inherent directional control and sealing without requiring additional valves. This friction-driven approach eliminates valve leakage while maintaining reliable fluid direction control.
4Measurement precision
If large working volumes are used in conventional pumps, then fluid storage is achieved, but dose accuracy and reliability are reduced
Solution Approach 1:
The pump chamber volume is made dynamic through the telescoping action of the plug within the piston. The chamber volume changes continuously as the plug moves relative to the piston, allowing precise control of the fluid displacement volume. This dynamic volume adjustment enables accurate dosing while minimizing the maximum system volume exposed to back pressure, as the chamber only expands to the extent needed for each specific dose.
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 solution provides a compact, reliable, and accurate insulin delivery system with reduced risk of leakage and mechanical failure, suitable for wearable patches.
Implementation Method 1
the plug is configured with a frictional engagement relative to the housing that provides an amount of friction to cause translation of the plug to lag relative to the piston until the amount of friction is overcome by translation of the piston
Data Source
AI summary
A pump subsystem for fluid delivery (e.g., in a wearable patch pump) is provided wherein pumping action is generated by linear piston movement that pulls a plug, which is interconnected to the piston between two mechanical extremes or end stops in a telescopic or variable volume fluid chamber. Such interconnection enables piston and plug to move a certain distance with respect to each other that corresponds to a predefined swept volume of the pump subsystem. Telescoping-like effect of relative piston and plug movement provides for intake and discharge of fluid with respect to the fluid chamber. Movement of plug within piston can be enabled by the friction of seals placed on the plug, which serve to provide resistance to piston motion and therefore force translation motion of the plug to lag relative to the piston translation motion during portions of the pump cycle.