Torsional Insertion Mechanism for Controlled Cannula Insertion and Retraction

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Solution Overview

Problem

Existing insulin infusion systems face challenges in efficiently and reliably inserting cannulas into subcutaneous tissue, particularly in managing the insertion and retraction of introducer needles while ensuring secure attachment to patch pump assemblies.

Innovation Solution

A torsional insertion mechanism utilizing a torsion spring to impart rotational motion to a rotatable assembly, which drives a piston mechanism to pierce tissue with a captive introducer needle and insert a cannula, with a latch mechanism for secure attachment to a disposable patch pump assembly, allowing for controlled cannula insertion and retraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional linear insertion mechanism is used, then the structure is simple, but the reliability of cannula insertion and retraction is insufficient

Engineering Contradiction:

Improvereliability of cannula insertion and retractionVSAvoidcomplexity of insertion mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by transitioning from a static linear insertion mechanism to a dynamic torsional mechanism. The rotatable assembly rotates between a first position (cannula inserted), second position (cannula retracted), and third position (introducer needle retracted), enabling controlled sequential motion that improves reliability while managing complexity through defined positional states

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The insertion mechanism is segmented into distinct functional components: the torsion spring for energy storage, the rotatable assembly for motion control, the piston mechanism for linear actuation, and the introducer needle with cannula as separate elements. This segmentation allows each component to perform its specific function reliably while the overall system manages complexity through modular design

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If a torsional insertion mechanism is used, then the control over cannula insertion and retraction is improved, but the device complexity increases

Engineering Contradiction:

Improvecontrol over cannula insertion and retractionVSAvoidcomplexity of insertion mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The torsional insertion mechanism employs periodic action through the cyclic rotation of the rotatable assembly between defined positions. The torsion spring stores and releases energy in periodic cycles, driving the assembly through sequential positions (first, second, third) that correspond to different stages of cannula and introducer needle deployment and retraction, providing controlled periodic operation

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The torsion spring provides self-service by automatically storing energy during the insertion phase and releasing it to drive the retraction phase without external intervention. The mechanism serves itself through the inherent elastic properties of the torsion spring, which continuously cycles between wound and unwound states, enabling autonomous control of the insertion and retraction operations

Inventive Principle:

Principle #25Self-service

3Reliability

If a secure attachment mechanism is used, then the attachment to patch pump assembly is reliable, but the device complexity increases

Engineering Contradiction:

Improveattachment to patch pump assemblyVSAvoidcomplexity of attachment mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The latch mechanism merges multiple functions into a single integrated component: it provides both the attachment function (securing the pump assembly to the dispenser) and the release function (allowing controlled detachment). The latch member combines the locking engagement with the release actuation in one unified structure, achieving reliable attachment while minimizing the number of separate parts

Inventive Principle:

Principle #5Merging (Combining)

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

Enables efficient, controlled cannula insertion and retraction, ensuring secure attachment to patch pump assemblies, and facilitates reliable fluid delivery of medicaments like insulin.

Implementation Method 1

a torsion spring configured to impart rotational motion to a rotatable assembly and rotate the rotatable assembly between a first position and a second position in response to the rotational motion

Methodology Applied

Scientific EffectTorsion spring: Torsion Spring

Data Source

PatentUS12447269B2Torsional insertion devices

Publication Date: 2025.10.21 MEDTRONIC MINIMED INC

AI summary

This disclosure relates to a detachable insertion mechanism that includes a torsion spring configured to impart rotational motion to a rotatable assembly and rotate the rotatable assembly between a first position and a second position in response to the rotational motion and a piston mechanism connected to a distal portion of the torsion spring and configured to move from a first insertion position to a second insertion position in response to the motion of the rotatable assembly. The piston mechanism includes a captive introducer needle disposed thereon. The captive introducer needle is configured to pierce tissue.