Low-Stress Valve Forming for Low-Force Wearable Drug Delivery

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Solution Overview

Problem

Current wearable drug delivery devices face challenges in creating low-force valves without using rubber seals or requiring tight part tolerances, making them unsuitable for small, low-cost, on-body devices.

Innovation Solution

A method involving an interference fit between a tube and a cylinder, followed by an annealing process to relieve stress and resize the components, allowing them to move with lower force after cooling, eliminating the need for rubber seals and tight tolerances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If rubberless valves are used with wide interference range, then device complexity is reduced, but operating force becomes too high for wearable devices

Engineering Contradiction:

Improvevalve structure complexityVSAvoidvalve operating force

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The patent applies thermal parameter changes by heating the valve components to expand the tube, reducing the interference fit and thereby reducing the operating force required to move the cylinder, while maintaining the simple rubberless structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes thermal expansion of the tube material when heated, causing the tube to expand and reduce the interference fit with the cylinder, which directly reduces the force needed to operate the valve without requiring rubber seals or tight tolerances

Inventive Principle:

Principle #37Thermal expansion

2Force

If precision machining or grinding is used to create tight tolerances, then valve operating force is reduced, but manufacturing cost increases

Engineering Contradiction:

Improvevalve operating forceVSAvoidmanufacturing cost

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

Instead of using expensive precision machining to achieve tight tolerances, the patent uses thermal parameter changes to dynamically adjust the interference fit, allowing standard manufacturing tolerances to be used while still achieving low operating force

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary thermal action by heating the valve components before operation to pre-reduce the interference fit, so that the valve is ready for low-force operation without requiring expensive precision manufacturing

Inventive Principle:

Principle #10Preliminary action

3Strength

If interference fit is maintained to ensure structural integrity, then component strength is improved, but component size must be larger for wearable devices

Engineering Contradiction:

Improvecomponent structural strengthVSAvoidvalve component size

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The patent transforms the static interference fit into a dynamic condition by using thermal expansion to temporarily reduce the interference during operation, allowing the components to move with lower force while maintaining structural integrity when cold

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses thermal expansion to temporarily increase the tube diameter when heated, reducing the interference fit and allowing smaller component dimensions to be used in wearable devices while maintaining sufficient strength through the thermal cycling mechanism

Inventive Principle:

Principle #37Thermal expansion

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 enables the creation of low-force valves that reduce component size and cost, suitable for small, low-cost wearable medical devices like insulin delivery systems, while maintaining functionality.

Implementation Method 1

annealing the tube and the cylinder, wherein the tube and the cylinder are no longer joined together in the interference fit following the annealing

Methodology Applied

Scientific EffectAnnealing: Annealing

Implementation Method 2

annealing the tube and the cylinder, and cooling the tube and the cylinder after the annealing until the cylinder and the tube are no longer engaged in the interference fit

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

cooling the tube and the cylinder after the annealing until the cylinder and the tube are no longer engaged in the interference fit

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS11305333B2Methods for forming low stress component for medical devices

Publication Date: 2022.04.19 INSULET CORP

AI summary

Disclosed herein are approaches of forming a component, such as a valve, for a medical device. One approach includes providing a cylinder within a tube, the tube and the cylinder joined together in an interference fit, and annealing the tube and the cylinder, wherein the tube and the cylinder are no longer joined together in the interference fit following the annealing.