Ampoule Adapter Threaded Piston Slipstick
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Solution Overview
Problem
Existing administration devices for dispensing small amounts of fluid, such as insulin or medical substances, often experience slipstick issues due to static and sliding friction between the piston and the ampoule, leading to inconsistent dosing, with potential under- or over-supply of the medication.
Innovation Solution
An ampoule unit comprising a commercially available ampoule and a securely connected adapter with a threaded engagement that allows for a combined rotary and linear movement of the piston unit, overcoming static friction and ensuring consistent dispensing by covering a spiral path within the ampoule.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linearly guided plunger is used to dispense fluid from the ampoule, then the device structure is simple, but static friction between the stopper and ampoule wall causes slipstick problems leading to inconsistent dosing
Solution Approach 1:
The patent introduces a rotational movement component to the linear plunger motion, creating a spiral or curved path instead of a straight line. This curvature changes the friction dynamics between the stopper and ampoule wall, converting static friction dominance into sliding friction dominance, thereby eliminating slipstick effects and ensuring consistent dosing.
Solution Approach 2:
The invention transforms the static linear plunger motion into a dynamic rotational-linear combined motion. By adding rotational degrees of freedom to the plunger mechanism, the system dynamically adjusts the stopper's path through the ampoule, maintaining consistent contact pressure and friction characteristics throughout the dispensing process.
2Device complexity
If the piston is held back by static friction during small dispensing quantities, then the device can be simple, but the distributed amount becomes too small or zero, and subsequent distributions become too large
Solution Approach 1:
The rotational component introduces a curved or spiral motion path for the piston, which modifies the frictional interaction between the piston and ampoule wall. This curvature ensures that the piston maintains consistent sliding contact rather than sticking, enabling precise control of small dispensing quantities and eliminating the variability between consecutive doses.
Solution Approach 2:
The patent replaces the purely linear mechanical plunger system with a rotational-linear hybrid mechanism. This substitution fundamentally changes the force distribution and friction characteristics, allowing for more precise control over the piston movement and dispensing quantity, especially for small volumes.
3Strength
If a threaded connection is used between the adapter and ampoule, then the adapter can be securely connected, but the device complexity increases
Solution Approach 1:
The invention separates the adapter into distinct functional segments: a connection portion with threaded engagement for secure attachment to the ampoule, and a drive portion with the spiral groove for piston control. This segmentation allows each part to be optimized independently while maintaining overall simplicity.
Solution Approach 2:
The adapter serves multiple functions simultaneously: it provides a secure threaded connection to the ampoule, guides the rotational-linear motion of the piston, and controls the dispensing process. This multi-functionality reduces the need for additional separate components, maintaining device simplicity despite the added complexity of the threaded connection.
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 ensures reliable and reproducible dispensing of the same amount of fluid each time, minimizing slug volume and delivery delays, and preventing free flow while reducing slipstick problems, thus providing consistent medication supply.
Implementation Method 1
The adapter (4) has a thread (4a) with a mating thread (2a) of a piston unit (2), into which the piston unit (2) can be screwed for dispensing the fluid product contained in the ampoule (1)
Implementation Method 2
there is always an alternation between static friction and sliding friction between the stopper and the inner wall of the ampoule
Implementation Method 3
the piston is held back by the static friction during such a distribution
Data Source
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AI summary
The unit has an ampoule (1) comprising a distal end with an opening (10) for dispensing a fluid product and a proximal end with an opening for accommodating a displacement body or displacement body unit. An adapter (4) is connected with the ampoule, and the proximal end has a thread (4a) that is brought into a thread engagement with a complementary thread, which is part of the displacement body or unit. A piston unit (2) has a piston that is made from elastic material and seals the ampoule in a proximal direction, where the piston has a concave form along the circumference.