Drug Delivery Dose Counter with Ratchet Lockout
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Solution Overview
Problem
Multi-shot drug delivery devices lack a simple and cost-efficient end-of-content indication mechanism, which can lead to dangerous situations where users attempt to administer doses beyond the remaining amount in the drug reservoir.
Innovation Solution
A drug delivery device with a counting mechanism that tracks the number of doses expelled and available, using a combination of unidirectional ratchet mechanisms and electronic or mechanical components to prevent further dose expelling actions once the predetermined number is reached, ensuring safe disposal and user notification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-of-content indication mechanisms are added to multi-shot devices, then user safety is improved by preventing over-administration, but device complexity increases
Solution Approach 1:
The counting mechanism automatically tracks doses through the ratchet system that engages with the piston rod's reciprocating motion, eliminating the need for manual dose tracking by the user. The mechanism self-registers each dose delivery through mechanical engagement.
Solution Approach 2:
The patent replaces complex electronic or optical dose counting systems with a simple mechanical ratchet and pawl system that uses the existing reciprocating motion of the piston rod to advance the counting mechanism, reducing overall device complexity while maintaining reliability.
2Measurement precision
If dose counting mechanisms are implemented, then accuracy of dose tracking is improved, but manufacturing cost increases
Solution Approach 1:
The counting mechanism is merged with the existing dose expelling mechanism by using the piston rod's reciprocating motion as the driving force for the ratchet system. This integration eliminates the need for separate counting components and reduces manufacturing complexity.
Solution Approach 2:
The patent employs simple, inexpensive mechanical components such as ratchet wheels, pawls, and spring elements that can be manufactured at low cost using conventional machining processes, making the device economically viable for single-use or limited-use applications.
3Reliability
If lockout mechanisms are added to prevent further dose expelling, then reliability is improved by preventing incomplete dose delivery, but device complexity increases
Solution Approach 1:
The lockout mechanism proactively prevents further dose expelling attempts before incomplete delivery can occur. The ratchet system mechanically blocks the piston rod from returning to the retracted position once the predetermined number of doses has been delivered, eliminating the risk of incomplete dose administration.
Solution Approach 2:
The ratchet and pawl system acts as an intermediary mechanical barrier between the activation means and the piston rod, mediating the dose delivery process by allowing controlled reciprocating motion for the predetermined number of doses and then blocking further motion to prevent incomplete delivery.
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
Provides a reliable and cost-effective means to track doses and prevent over-administration, ensuring user safety by effectively indicating when the device should be discarded, thus eliminating the risk of incomplete or excessive dose delivery.
Implementation Method 1
a first unidirectional ratchet mechanism preventing motion in the first axial direction while allowing motion in the second axial direction of the reciprocating element relative to the counter element
Implementation Method 2
a second unidirectional ratchet mechanism allowing motion in the first axial direction while preventing motion in the second axial direction of the counter element relative to the housing
Data Source
AI summary
A drug delivery device includes a dose counting mechanism and an end-of-content or remaining-dose indication. For example, a dose expelling mechanism is coupled to a reciprocating element configured to undergo a predefined motion during each dose expelling action to allow a dose to be expelled. The predefined motion includes displacement in a first axial direction from a first position to a second position followed by displacement in a second axial direction from the second position to the first position, with a counter element being movable in the first axial direction. First and second unidirectional ratchet mechanisms prevent motion in the first axial direction and allow motion in the second axial direction of the reciprocating element relative to the counter element, and vice versa, respectively.