Pharmaceutical Injection Device Gasket Deformation Compensation
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Solution Overview
Problem
The use of thinner injection needles in pharmaceutical injection devices leads to variations in drug injection amounts due to increased resistance in the flow path, causing difficulties in delivering the set amount of medication effectively, as the gasket compression prevents smooth drug flow.
Innovation Solution
The pharmaceutical injection device incorporates a controller that measures the motor rotation frequency and current to account for the deformation of the gasket, allowing for precise control of the plunger movement to ensure accurate drug delivery, even with thinner needles, by storing data on the gasket deformation characteristics and adjusting the motor rotation accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a thinner injection needle is used to ease pain, then patient comfort is improved, but the flow path resistance increases causing injection amount variation
Solution Approach 1:
The encoder detects the actual rotation amount of the motor, and the controller compares this with the commanded rotation amount to detect gasket deformation. This feedback mechanism allows the system to compensate for variations caused by thin needle resistance, maintaining accurate injection amounts despite the increased flow path resistance.
Solution Approach 2:
The system changes the control parameter from fixed rotation frequency to adaptive rotation control based on detected gasket deformation. By monitoring the relationship between commanded and actual rotation amounts, the system adjusts the injection process to account for variations in flow path resistance caused by different needle gauges.
2Productivity
If the gasket is pressed by the plunger to inject drug, then drug delivery is achieved, but the gasket compresses preventing proper injection with thin needles
Solution Approach 1:
The encoder provides real-time feedback on the plunger's actual movement by detecting motor rotation. The controller uses this feedback to distinguish between intentional plunger movement for drug delivery and unwanted gasket compression, allowing it to compensate and maintain accurate injection amounts even when gasket compression occurs due to high resistance from thin needles.
Solution Approach 2:
The system replaces purely mechanical control of plunger movement with an electromechanical control system that uses encoder feedback and controller algorithms to monitor and adjust plunger movement. This substitution allows the system to detect and compensate for gasket deformation that would otherwise go unnoticed in a purely mechanical system.
3Reliability
If motor rotation frequency is controlled based on stored data, then injection amount variance is suppressed, but it cannot account for gasket deformation with thin needles
Solution Approach 1:
The encoder provides real-time feedback on actual motor rotation, enabling the controller to detect deviations from expected rotation caused by gasket deformation. This feedback mechanism allows the system to adapt to different needle sizes and resistance levels, overcoming the limitation of fixed stored data approaches.
Solution Approach 2:
The system transitions from static control based on pre-stored data to dynamic control that continuously monitors and adjusts based on actual motor rotation and gasket deformation detection. This dynamic approach enables the system to adapt to varying conditions including different needle gauges and resistance levels.
Data Source
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AI summary
The pharmaceutical injection device (100) comprises a syringe mounting portion (2) configured to mount thereon a syringe (9) containing a drug (12), the syringe including at a front end side thereof an injection needle mounting portion (10) on which an injection needle is mounted and a gasket (11) at a rear end side thereof, a plunger (13) operable to press the gasket (11) in the syringe (9) mounted on the syringe mounting portion (2) toward the injection needle mounting portion (10), a motor (14) operable to drive the plunger (13), an encoder (15) operable to detect a rotation amount of the motor (14), and a controller (17) connected to the encoder (15) and operable to control a driving of the motor (14). The controller (17) is operable to obtain a motor rotation amount that corresponds to a deformation amount of the gasket (11) deformed by the plunger (13), and control a rotation of the motor at a time of injection of the drug (12) in accordance with the motor rotation amount.