Pressure-Driven Needle Insertion and Retraction for Wearable Injectors
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Solution Overview
Problem
Existing drug delivery devices face issues such as patient discomfort and increased complexity due to rigid needles left inside the body for extended periods, and existing insertion mechanisms increase device size, complexity, and cost.
Innovation Solution
A wearable drug delivery device with an insertion mechanism that uses a pressure supply system to move a needle or cannula between retracted and extended positions, utilizing a retraction member and pressure differentials to control needle deployment and retraction, with features like biasing mechanisms, sealing mechanisms, and latches to secure the needle in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a rigid injection member is left inside the patient for extended periods to deliver viscous drugs, then the drug delivery function is maintained, but patient discomfort and unease increase
Solution Approach 1:
The needle assembly is designed to be movable between retracted and extended positions rather than fixed. A retraction mechanism allows the needle to be automatically retracted after drug delivery, transforming the static needle retention into a dynamic process that reduces patient discomfort while maintaining drug delivery function during the extended wear period
Solution Approach 2:
The device is configured to be attached to the patient at a doctor's office with the needle already in place, then automatically retracted before the patient returns home. This preliminary action of retracting the needle while maintaining device attachment eliminates the need for patients to see or handle the needle, reducing anxiety and discomfort
2Reliability
If external safety features are added to the device, then needle safety is improved, but the device size and complexity increase
Solution Approach 1:
The retraction mechanism is designed to automatically retract the needle after drug delivery without requiring external safety features or manual intervention. The spring-loaded retraction system and pressure differential mechanism self-actuate to secure the needle, eliminating the need for additional external safety components while maintaining high reliability
Solution Approach 2:
The safety function is merged with the drug delivery mechanism itself. The retraction mechanism that drives needle withdrawal is integrated into the existing pressure differential system used for drug delivery, combining multiple functions into a single mechanism rather than adding separate safety features
3Ease of operation
If an insertion mechanism is disposed within the drug delivery device to accomplish needle insertion and retraction, then needle control is improved, but the overall size, complexity, and cost of the device increase
Solution Approach 1:
The device uses pressure differential mechanisms (pneumatic principles) to control needle insertion and retraction. Pressure applied to the proximal chamber moves the needle assembly forward, while pressure in the distal chamber retracts it, eliminating the need for complex mechanical insertion mechanisms and reducing overall device complexity
Solution Approach 2:
Traditional mechanical insertion mechanisms (motors, actuators, linkages) are replaced with a pressure-driven system. The needle assembly moves in response to pressure differentials between chambers rather than mechanical actuation, simplifying the device structure while maintaining precise control over needle deployment and retraction
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 minimizes patient discomfort by ensuring smooth and controlled needle deployment and retraction, reducing the need for external safety features and minimizing device size and complexity.
Implementation Method 1
The pressure supply device supplies pressure through the first opening and into the proximal chamber until an amount of pressure P1 in the proximal chamber applies an application force to the proximal surface of the base that surpasses the resistive force of the retraction member to move the needle assembly from the retracted position to the extended position
Data Source
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AI summary
An insertion mechanism for a drug delivery device. The insertion mechanism includes a proximal end, a distal end, a first opening disposed near the proximal end, and a second opening disposed in the distal end. A needle or cannula assembly is disposed within the housing and has a base with a proximal surface and a distal surface and a needle or cannula coupled to the distal surface. A retraction member is disposed within the housing to maintain the needle or cannula assembly in the retracted position before movement to the extended position, the retraction member in contact with the base. Upon supplying pressure through the first opening until an amount of pressure P1 applies an application force to the proximal surface of the base that surpasses a resistive force of the retraction member, the needle assembly is moved from the retracted position to the extended position.