Cartridge Bung Load Indicator for Pen-Injector Dose Feedback
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Solution Overview
Problem
Current drug delivery devices, particularly pen-injectors, face challenges in ensuring complete dose delivery due to compliance in the cartridge and drive mechanism, leading to potential under-dosing when using small gauge needles, and lack of feedback for users regarding blocked needles, which can result in partial or complete occlusions.
Innovation Solution
A cartridge bung load indicator is introduced, which uses relative fluid pressure to determine the dosing state and blocked needle conditions by activating a visual, audible, or tactile indicator element, replacing traditional bearing components with a low-cost compliant sub-assembly that provides feedback on load states, ensuring users are aware of successful dose delivery or potential blockages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional bearing components are used to ensure reliable dose delivery, then the device structure becomes complex and costly, but if low-cost compliant sub-assembly is used, then manufacturing cost is reduced but reliability may be compromised
Solution Approach 1:
The patent applies the disposable principle by using a low-cost compliant sub-assembly (cartridge bung load indicator) that can be discarded with the cartridge after use. This eliminates the need for expensive, complex bearing components that would need to be reused, while ensuring reliable dose delivery for each single use. The compliant sub-assembly provides sufficient reliability for its intended lifecycle without requiring the complexity of traditional bearing mechanisms.
Solution Approach 2:
The patent extracts the essential function of load indication from complex bearing components and implements it through a simplified compliant sub-assembly. By taking out only the necessary load-sensing and indication functions and implementing them through a minimal compliant structure with visual indicators, the design achieves reliable dose delivery feedback without the complexity and cost of traditional bearing mechanisms.
2Reliability
If no load indicator is provided, then the device structure remains simple, but users cannot detect blocked needles or incomplete dose delivery
Solution Approach 1:
The patent applies color changes as a visual indication mechanism. The cartridge bung load indicator includes visual indicators (such as colored elements or windows) that change appearance based on the load state, allowing users to easily detect whether the needle is blocked or dose delivery is complete. This provides reliable feedback without requiring complex electronic or mechanical indicator systems.
Solution Approach 2:
The compliant sub-assembly performs self-service by automatically indicating the load state through its mechanical compliance and visual indicators. As the piston rod moves and applies load to the cartridge bung, the compliant sub-assembly naturally deforms or shifts to reveal visual indicators, providing automatic feedback without requiring external sensors, power sources, or complex control mechanisms.
3Object-affected harmful factors
If small gauge needles are used to reduce patient discomfort, then injection pain is reduced, but the risk of needle blockage and incomplete dose delivery increases
Solution Approach 1:
The patent applies feedback by implementing visual indicators on the cartridge bung load indicator that provide real-time information to the user about dose delivery status. When a small gauge needle is used, the compliant sub-assembly and visual indicators allow the user to confirm whether the full dose has been delivered or if the needle has become blocked, enabling immediate detection and correction of delivery problems that are more likely with smaller needles.
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 cartridge bung load indicator enhances user convenience by providing real-time feedback on dose delivery progress and needle blockages, mitigating the risk of under-dosing and ensuring complete medicament administration.
Implementation Method 1
A cartridge bung load indicator is introduced, which uses relative fluid pressure to determine the dosing state and blocked needle conditions
Implementation Method 2
The first cartridge bung indicator component is compressible in the axial direction, for example by means of a coil spring
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention refers to a drug delivery device (1) with a piston rod (6) which extends along a longitudinal axis of the drug delivery device (1), wherein the piston rod (6) is adapted to apply an axial load in the distal direction to a cartridge bung (27) in order to dispense a medicament contained in the cartridge (25). In order to improve the convenience of the injection process and to mitigate the risk of underdosing due to a blocked needle a cartridge bung load indicator (40, 60, 70) is provided, located at the distal end of the piston rod (6) and adapted to abut against the cartridge bung (27), wherein the cartridge bung load indicator (40, 60, 70) comprises an indicator element (53, 62, 71) that audibly, tangibly and/or visually indicates a load state of the piston rod (6) to the user.