Drug Delivery Lead Screw Feedback Ratchet Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drug delivery devices, particularly pen-type injection devices, suffer from design flaws that lead to inaccurate dosing and lack of feedback for users, especially those with impaired vision or dexterity, increasing the risk of improper injection and under-dosing, which can be fatal in some cases.
Innovation Solution
The design incorporates a lead screw with a helical thread and a feedback ratchet mechanism that provides audible and tactile feedback during dose setting and delivery, ensuring the user is informed about the injection progress and completion, with distinct feedback signals for setting and dispensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a lead screw mechanism is used to advance the piston and dispense medication, then the device enables dose setting and delivery functionality, but the device lacks feedback to inform users about injection progress and completion
Solution Approach 1:
The patent implements a feedback ratchet mechanism that generates audible clicks during dose setting and delivery. The ratchet arm engages with ratchet teeth on the lead screw, producing distinct click patterns that inform the user about the current operation state (setting vs. delivery) and progress, thereby preventing information loss and ensuring reliable dosing.
2Reliability
If the lead screw is made axially movable to enable dose delivery, then the device can dispense medication, but the device becomes vulnerable to counterfeiting and improper use
Solution Approach 1:
The patent incorporates a feedback ratchet mechanism that provides preliminary warning through distinct audible feedback signals. The ratchet arm engages with ratchet teeth to produce specific click patterns during dose setting and delivery, alerting users to the device's operational state before critical actions occur, thereby preventing counterfeiting and improper use while maintaining ease of operation.
3Ease of operation
If the device provides detailed feedback during dose delivery, then users with impaired vision or dexterity can safely use the device, but the device complexity increases
Solution Approach 1:
The patent implements a feedback ratchet mechanism that generates audible clicks during dose setting and delivery. The ratchet arm engages with ratchet teeth on the lead screw, producing distinct click patterns that inform the user about the current operation state (setting vs. delivery) and progress, thereby preventing information loss and ensuring reliable dosing.
4Reliability
If a feedback ratchet mechanism is added to provide audible and tactile feedback, then user safety and dosing accuracy improve, but the device complexity and number of components increase
Solution Approach 1:
The patent implements a feedback ratchet mechanism that generates audible clicks during dose setting and delivery. The ratchet arm engages with ratchet teeth on the lead screw, producing distinct click patterns that inform the user about the current operation state (setting vs. delivery) and progress, thereby preventing information loss and ensuring reliable dosing.
Solution Approach 2:
The feedback ratchet mechanism serves multiple functions: it provides audible feedback during dose setting, continues to provide feedback during dose delivery, and prevents reverse movement of the lead screw. This multi-functionality reduces the need for separate components for each function, thereby limiting the increase in device complexity.
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 solution enhances user safety by providing clear feedback on dose delivery, preventing under-dosing and ensuring accurate medication administration, even for users with impaired vision or dexterity, thus improving the reliability of drug delivery devices.
Implementation Method 1
a lead screw having a longitudinal axis, a distal end and a proximal end that is rotatably fixed during dose setting and dose delivery and axially movable in a distal direction relative to the housing
Implementation Method 2
The dial link comprises a first portion of a feedback ratchet. The lead screw comprises a second portion of the feedback ratchet
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An assembly (1) for a drug delivery device (1) is provided, the assembly (1) comprising a housing (4), and a lead screw (22) having a longitudinal axis, a distal end and a proximal end, the lead screw (22) being rotatably fixed during dose setting and dose delivery and axially movable in a distal direction relative to the housing (4), the lead screw (22) further including a thread (33). The assembly (1) further comprises a drive nut (23) threadedly engaged with and screwable along the lead screw thread (33)and a dial link (25) connected with the drive nut (23) and axially movable and rotatably fixed relative to the drive nut (23), where the dial link (25) comprises a first portion of a feedback ratchet (80, 81). The assembly is configured such that, during dose setting, the dial link (25) is moved relative to the housing (4) a first axial distance from a home position and the drive nut (23) is moved along the thread (33) a second axial distance and wherein,during dose delivery, the dial link (25) is moved relative to the housing (4) back toward the home position, and the drive nut (23) and therewith the lead screw (22) is advanced axially, and where the assembly comprises a second portion of the feedback ratchet (80, 81), wherein the second portion is arranged and configured to engage the first portion such that, during dose delivery, the contact between said portions generates a feedback signal.