Capacitance Gas Bubble Sensor for Medical Flow Lines
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Solution Overview
Problem
Existing gas bubble sensors in liquid flow lines, particularly in medical fluid administration systems, rely on optical properties and opacity, which limits their accuracy and precision in detecting harmful gas bubbles, and they do not account for bubble size effectively.
Innovation Solution
A capacitance-based gas bubble sensor using conductive plates forming a capacitor that measures changes in dielectric properties of the liquid flow line, allowing for the detection of gas bubbles independent of optical properties, with a control system to alert or modify operations based on predetermined bubble volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used to detect gas bubbles, then the detection function is provided, but the accuracy and precision are limited due to dependence on optical properties and opacity
Solution Approach 1:
The patent replaces optical sensors with a capacitance-based sensing system that uses electrical fields instead of light to detect gas bubbles. The capacitance sensor measures changes in dielectric properties of the liquid, providing bubble detection that is independent of optical properties, transparency, or color of the liquid medium.
Solution Approach 2:
The patent changes the detection parameter from optical properties (light absorption, reflection, transparency) to electrical properties (capacitance, dielectric constant). This parameter change allows the sensor to detect bubbles based on the difference in dielectric properties between gas and liquid phases, achieving consistent detection regardless of the liquid's optical characteristics.
2Adaptability or versatility
If capacitance-based sensing is used, then independence from optical properties is achieved, but device complexity increases due to conductive plates and capacitance measurement circuitry
Solution Approach 1:
The conductive plates serve multiple functions: they form the capacitor for sensing, can be integrated into existing device housings or flow line components, and the same structure can potentially serve as electrodes for other electrical measurements. This multi-functionality reduces overall system complexity despite the capacitance sensing requirement.
Solution Approach 2:
The patent describes conductive plates that can be positioned adjacent to the flow line, potentially using flexible or thin conductive structures that can be integrated into various device geometries. This flexibility allows the sensing system to adapt to different device configurations without requiring complex rigid structures.
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
Accurately detects gas bubbles and their volumes, ensuring safe operation by preventing harmful bubbles from reaching patients and adapting system operations to prevent gas intrusion, enhancing safety and reliability in medical fluid administration.
Implementation Method 1
first and second conductive plates forming a capacitor with a capacitance that varies with the dielectric properties of a liquid flow line
Implementation Method 2
a capacitance sensor measuring the capacitance between the first conductive plate and the second conductive plate; and a control system programmed to determine a presence of one or more gas bubbles within the liquid flow line based on the capacitance
Data Source
AI summary
Systems, devices, and methods are provided for sensing gas bubbles within a liquid flow line, such as within a medical device. The systems, devices, and methods can measure a change in capacitance across a pair of conductive plates to calculate a volume of gas in a flow line. If a calculated volume of gas exceeds an established threshold, an alert can be sent and/or changes made to operation of the device.