Auto-injector Motor-Driven Plunger and Interlock Switch
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Solution Overview
Problem
Current auto-injector devices face challenges such as user error in administering complete doses, high injection forces, and discomfort due to manual operation, and lack of safety features for needle handling and drug specificity.
Innovation Solution
A reusable auto-injector with a motor-driven plunger system, encoder sensor, and interlock switch that ensures proper needle placement and operation, providing haptic and visual feedback, and allowing for user-selectable speed profiles and drug-specific settings, including RFID or barcode detection for medicament identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual devices are used, then the user can control the injection process, but the user must provide continuous mechanical energy and may deliver incomplete doses
Solution Approach 1:
The auto-injector device performs the injection function automatically without requiring continuous user intervention. The spring mechanism self-activates upon needle insertion, and the motor automatically retracts the needle and advances the plunger, allowing the device to serve itself rather than requiring continuous manual operation.
Solution Approach 2:
The patent replaces the manual mechanical button-pressing system with an automated motor-driven plunger advancement system. The motor, controlled by a microprocessor, substitutes for the user's manual mechanical energy input, ensuring complete dose delivery without requiring the user to continuously press a button.
2Productivity
If high injection forces are applied, then the medicament can be delivered effectively, but the user experiences discomfort and hand shaking
Solution Approach 1:
The patent replaces the user-applied mechanical force system with a motor-driven force delivery system. The motor provides the necessary injection forces without requiring the user to physically push, eliminating hand shaking and discomfort while maintaining effective medicament delivery.
Solution Approach 2:
The injection process is divided into periodic phases: needle insertion, medicament delivery, and needle retraction. The motor controls plunger advancement in controlled increments during the delivery phase, providing effective injection forces in a regulated periodic manner rather than continuous high-force application.
3Ease of operation
If the button extension is made long, then the user can reach the activation point, but the device becomes harder to handle and causes more shaking
Solution Approach 1:
The device eliminates the need for a long button extension by making the activation self-serve. The spring mechanism automatically activates upon needle insertion, and the motor automatically performs subsequent actions, removing the need for the user to reach and press an extended button.
Solution Approach 2:
Instead of requiring the user to activate the device by pressing a button, the patent inverts the activation sequence: the act of inserting the needle into the skin triggers the spring activation, which then automatically initiates the injection process without requiring the user to reach for or press a separate activation button.
4Extent of automation
If spring-based energy delivery is used, then the injection can be automated, but the device lacks precision control and safety features
Solution Approach 1:
The patent incorporates multiple feedback mechanisms: an interlock switch detects needle insertion and activates the spring only when properly positioned; an encoder sensor provides feedback on plunger position to the microprocessor; and the microprocessor monitors the injection process to control motor-driven needle retraction and plunger advancement, ensuring precise dose delivery.
Solution Approach 2:
The device combines multiple functions in a single integrated system: spring-based automated injection, motor-driven needle retraction, encoder-based position sensing, interlock switch safety, and microprocessor control. This multi-functional approach provides both automation and precision control within a single device architecture.
5Object-affected harmful factors
If needle retraction is performed manually, then the device structure can be simple, but needle stick injuries may occur
Solution Approach 1:
The needle retraction function is performed automatically by the motor without requiring manual user action. The motor-driven retraction mechanism self-activates after injection completion, pulling the needle back into the device housing and eliminating the need for the user to manually manipulate the needle.
Solution Approach 2:
The patent replaces manual needle retraction with an automated motor-driven retraction system. The motor provides controlled mechanical force to retract the needle, substituting for manual user manipulation and eliminating the risk of accidental needle stick injuries during the retraction process.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4B
AI summary
The invention relates to an auto-injector (A) for administering a dose of a liquid medicament, comprising: - a substantially tubular front-end device (1) adapted to contain a syringe (2) with an injection needle (2.2) and a barrel (2.3) containing the dose of the medicament and comprising a needle shroud (1.4) adapted to rest on the skin of a patient receiving an injection and - a reusable back-end device (3) comprising - a housing (3.1), - a plunger (3.2) connected to or adapted to engage a stopper (3.3) providing a fluid tight seal for a distal end of the barrel (2.3), - a motor (3.5) for displacing the plunger (3.2) connected to the stopper (3.3), wherein the front-end device (1) is attachable to the back-end device (3), wherein the needle shroud (1.4) is slidably arranged with respect to the injection needle (2.2) and wherein an interlock switch (3.10) is capable of detecting an axial position (PA, PR) of the needle shroud (1.4).