Infusion Device Overfill Protection via Magnetic Displacement Sensor
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Solution Overview
Problem
Implantable infusion devices face challenges with reservoir overfilling, which can lead to over-pressurization and adverse consequences, and existing refilling methods lack accuracy and ease of use, especially for less-experienced clinicians.
Innovation Solution
An implantable infusion device with a collapsible reservoir and a valve plunger system that includes a displacement sensor to detect the reservoir's full position, preventing overfilling and providing accurate feedback on fluid volume during refilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure-based detection is used to sense reservoir full capacity, then overfilling can be detected, but clinician variability still results in over or under-filling and the system is not adaptable to flexible reservoirs
Solution Approach 1:
The patent replaces pressure-based mechanical detection with a magnetic field-based displacement sensor system. The displacement sensor detects the position of the valve plunger through magnetic field interaction without mechanical contact, eliminating the need for pressure-based tactile detection and providing precise, consistent measurement of reservoir full capacity regardless of reservoir flexibility.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the valve plunger and the displacement sensor. This magnetic field intermediary allows the sensor to detect plunger position without direct mechanical contact or pressure application, enabling accurate detection while maintaining system adaptability to different reservoir types including flexible reservoirs.
2Reliability
If a pin valve is used to seal the fluid passageway, then overfilling is prevented, but aspiration requires sustained vacuum pressure and fluid leaks around the pin
Solution Approach 1:
The patent extracts the sealing function from a traditional pin valve configuration and relocates it to a valve plunger system that seals against a valve seat within the refill passageway. This separation allows the sealing mechanism to be independently optimized for both overfill prevention and ease of aspiration without the complications of fluid leaking around a pin.
Solution Approach 2:
The patent replaces the mechanical pin valve sealing mechanism with a valve plunger system actuated by magnetic field detection. The valve plunger provides reliable sealing against overfilling while being controllable through the displacement sensor system, eliminating the need for sustained vacuum pressure and preventing fluid leakage issues associated with pin valves.
3Reliability
If tactile syringe resistance is used to detect full capacity, then overfilling can be sensed, but inherent clinician variability results in inconsistent filling
Solution Approach 1:
The patent replaces tactile syringe resistance detection with an electronic displacement sensor system that uses magnetic field interaction to detect valve plunger position. This substitution eliminates clinician variability by providing objective, precise, and consistent measurement of reservoir full capacity through electrical rather than mechanical sensing.
Solution Approach 2:
The patent implements a feedback system where the displacement sensor continuously monitors valve plunger position and provides real-time information about reservoir fill status. This feedback mechanism replaces the ambiguous tactile feedback from syringe resistance with precise electronic signals, enabling accurate determination of full capacity and preventing overfilling through consistent, measurable parameters.
4Device complexity
If no feedback mechanism is provided, then device complexity is reduced, but it is difficult to determine needle position and fluid volume within the reservoir
Solution Approach 1:
The patent implements a feedback system using a displacement sensor that detects valve plunger position and provides information about reservoir fill status and needle positioning. This feedback mechanism restores critical information about fluid volume and system state without significantly increasing overall device complexity, as the sensor integrates seamlessly with the existing valve plunger mechanism.
Solution Approach 2:
The patent uses a magnetic field as an intermediary to transmit information from the valve plunger to the displacement sensor without adding mechanical complexity. This magnetic intermediary enables information transfer about needle position and fluid volume while maintaining a simple device architecture, avoiding the need for complex mechanical feedback linkages.
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
The system effectively prevents overfilling by occluding the refill passageway when the reservoir reaches full capacity, ensuring precise fluid management and reducing the risk of over-pressurization, while also providing clinician feedback for accurate needle placement and fluid volume monitoring.
Implementation Method 1
A displacement sensor is also provided and coupled to the housing. The displacement sensor is operable to detect a position of the free distal end of the valve plunger as the reservoir surface moves from the full position to the refill position.
Data Source
AI summary
A medical device and displacement-based over-pressurization mechanism (OPM) for use with the same. The OPM may be positioned in or along a refill passageway of the device. It may include a valve plunger having a portion in biased, abutting contact with a reservoir surface that moves as the reservoir volume changes. The reservoir surface may move between a full position and a refill position. The OPM is preferably configured to close and occlude the refill passageway when the reservoir and reservoir surface reach the full position, e.g., before reaching an overfill position. A sensor may also be provided to detect a position of the valve plunger.