Medicament Delivery Device Unidirectional Ratchet Sensor
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Solution Overview
Problem
Current medicament delivery devices with piston rods having a threaded outer surface face challenges in automatically logging medicament administration, as existing solutions fail to accurately detect the displacement of internal parts during drug administration.
Innovation Solution
A medicament delivery device featuring a rotatable plunger rod with a second direction rotation preventer and a recording unit that includes a sensor to detect rotation, allowing for accurate logging of dose expulsion data, using mechanisms such as ratchets, photo interrupters, or contactless magnetic sensors to ensure motion detection during drug administration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a sensor is arranged to detect displacement of internal parts in medicament delivery devices with threaded piston rods, then automatic logging capability is achieved, but it cannot be made certain that detection is attributed to medicament administration due to bidirectional rotation possibility
Solution Approach 1:
The patent introduces asymmetric ratchet teeth on the inner member that allow rotation only in the first direction (corresponding to medicament administration) while preventing rotation in the second direction. This asymmetric mechanical constraint ensures that sensor detection is exclusively attributed to legitimate medicament administration events, resolving the reliability issue while maintaining automatic logging capability
2Measurement precision
If a ratchet mechanism is introduced to prevent rotation in the opposite direction, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the ratchet mechanism for unidirectional rotation control with the sensor detection system into an integrated assembly. The inner member with ratchet teeth serves dual purposes: it prevents bidirectional rotation while simultaneously providing the rotational movement that the sensor detects. This merging reduces overall device complexity compared to having separate components for each function
Solution Approach 2:
The inner member is designed to perform multiple functions: it transmits rotational motion from the piston rod, provides unidirectional rotation control through ratchet teeth, and serves as the detection target for the sensor. This multi-functionality reduces the number of separate components needed, thereby managing device complexity while achieving detection accuracy
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
Ensures accurate and automatic logging of medicament administration by preventing rotation in the opposite direction, allowing for precise determination of the injected dose and facilitating compliance through wireless data transmission.
Implementation Method 1
The first sensor is an electromechanical switch in physical contact with the outer periphery of the inner member, and wherein the electromechanical switch is arranged to be actuated by interaction with the recesses
Implementation Method 2
contactless magnetic sensors to ensure motion detection during drug administration
Data Source
Figure 1~2a
Figure 2b~4
Figure 5~6
AI summary
The present disclosure relates to a medicament delivery device comprising: a housing (3), a plunger rod received by the housing (3), which plunger rod is rotatable in a first direction relative to the housing (3) and linearly displaceable, an activation button arrangement linearly displaceable from a first position to a second position to thereby rotate the plunger rod in the first direction, a second direction rotation preventer having an annular outer member that is rotationally fixed relative to the housing (3) and an annular inner member partially received by the outer member, wherein the outer member and the inner member are arranged to receive the plunger rod and wherein the inner member is rotationally interlocked with the plunger rod, wherein the outer member and the inner member are structured to allow the inner member to rotate in the first direction relative to the outer member and to prevent the inner member from rotating in a second direction opposite to the first direction, and a recording unit (5) comprising: a first sensor arranged to detect rotation of the inner member, and processing circuitry configured to generate dose expulsion data in response to detection of rotation of the inner member.