Ophthalmic Injection Device with Stepper Motor and Lead Screw
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Solution Overview
Problem
Current ophthalmic drug delivery systems lack precise dosage control and are prone to dosing errors due to uncontrolled fluid flow rates and manual inaccuracies, which can lead to tissue damage during eye injections.
Innovation Solution
A drug delivery device with a dispensing chamber, plunger, and controller that reads dosage data from a memory device resistant to sterilization, ensuring accurate delivery of a predetermined dosage through a controlled actuation mechanism, including a limited reuse assembly with a power source and actuator for precise dosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional syringe with vernier is used for manual injection, then the device is simple and easy to operate, but the dosage precision and fluid flow rate control are insufficient
Solution Approach 1:
The patent replaces the manual mechanical operation of a conventional syringe with an automated electromechanical system. A stepper motor drives a lead screw mechanism to precisely control plunger movement, eliminating manual vernier reading and parallax errors. The system uses a microcontroller to automate dosage delivery based on pre-programmed parameters, substituting human operation with automated mechanical control for improved precision.
Solution Approach 2:
The patent introduces a lead screw mechanism as an intermediary between the stepper motor and the plunger. This mechanical intermediary converts the rotational motion of the motor into precise linear displacement of the plunger, enabling accurate dosage control. The lead screw acts as a mediator that translates electrical control signals into controlled mechanical fluid delivery.
2Reliability
If manual syringe operation is used, then the device is easy to operate, but fluid flow rate remains uncontrolled and tissue damage may occur
Solution Approach 1:
The patent incorporates feedback control through the microcontroller that monitors and regulates plunger movement throughout the injection process. The system can detect injection progress and adjust delivery parameters in real-time, providing feedback control to ensure safe and controlled fluid delivery. This automated feedback mechanism prevents uncontrolled flow rates that could cause tissue damage.
Solution Approach 2:
The patent transforms the static manual injection process into a dynamic automated system. The stepper motor can adjust its speed and position dynamically during injection, allowing the system to optimize delivery parameters based on real-time conditions. This dynamic control enables the system to respond to varying injection requirements while maintaining safety and precision.
3Measurement precision
If a piezo-electric dispensing mechanism is used, then precise dosing is achieved, but the device becomes expensive and requires electrical signals
Solution Approach 1:
The patent employs a lead screw mechanism driven by a stepper motor, which is a more accessible and less complex electrical system compared to piezo-electric mechanisms. The system uses mechanical advantage through the lead screw to achieve precise linear displacement from rotational motor input, providing an alternative pneumatic-mechanical approach that balances precision with reduced electrical system complexity and cost.
Data Source
AI summary
An injection device includes a dispensing chamber, a plunger, a controller, a memory device resistant to sterilization, and a housing at least partially enclosing the dispensing chamber and the plunger. The dispensing chamber has an inner surface and an outer surface. The inner surface defines a cavity for receiving a quantity of a substance. The plunger is engaged with the inner surface of the dispensing chamber, is capable of sliding in the cavity of the dispensing chamber, and is fluidly sealed to the inner surface of the dispensing chamber. The controller controls the operation of the injection device. The controller reads dosage data from the memory device and operates the injection device to deliver a dosage corresponding to the dosage data.