Capacitive Gas Detection in Fluid Lines
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Solution Overview
Problem
Existing in-line fluid monitoring systems struggle to accurately detect and quantify gas bubbles and impurities without direct fluid contact, often generating false alarms due to velocity differences between gas bubbles and fluid, and are expensive, especially when using optical systems for medical applications.
Innovation Solution
A method and apparatus using capacitors to sense the capacitance of a fluid line, allowing for non-invasive detection of gas bubbles by comparing sensed capacitance to a reference, determining bubble size and flow rate, and minimizing false alarms through capacitance monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic or optical energy transmission is used to detect gas bubbles in fluid lines, then gas detection capability is improved, but the system becomes prohibitively expensive and complex
Solution Approach 1:
The patent replaces complex optical or ultrasonic detection systems with a simple capacitive sensing system. The capacitor plates are positioned on opposite sides of the fluid line, and changes in capacitance signal the presence of gas bubbles, eliminating the need for expensive transducers, light sources, and complex signal processing electronics.
Solution Approach 2:
The capacitive sensor system can be integrated into disposable fluid lines or catheters, allowing the entire monitoring system to be discarded after single use. This eliminates the need for expensive, reusable sensor systems with complex calibration and maintenance requirements.
2Reliability
If ultrasonic energy is used to detect gas bubbles, then gas presence indication is improved, but false alarms increase due to velocity differences between gas bubbles and fluid
Solution Approach 1:
The patent uses multiple capacitive sensors positioned at different locations along the fluid line to provide feedback on bubble position and movement. By comparing capacitance changes at multiple points, the system can determine bubble velocity and distinguish between stationary artifacts and moving gas bubbles, reducing false alarms.
3Reliability
If optical systems with image processing are used to detect impurities, then detection capability is improved, but cost becomes prohibitively expensive
Solution Approach 1:
The patent replaces expensive optical imaging systems with simple capacitive sensing. Instead of using cameras, lenses, and complex image processing algorithms, the system uses electrical field interactions with the fluid to detect gas bubbles and impurities, dramatically reducing system cost while maintaining detection capability.
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
This approach provides reliable and accurate detection of gas bubbles and impurities, reducing false alarms and enabling safe fluid delivery by accurately determining bubble size and flow rate, while being cost-effective for use with disposable fluid lines.
Implementation Method 1
sensing the capacitance of the fluid line at the first capacitor
Implementation Method 2
The different transmission characteristics of sound or light through fluids and gases may be utilized to form an indication of the presence of a gas bubble in liquid in the fluid line
Data Source
AI summary
A method and apparatus for monitoring fluid in a fluid line are disclosed. The apparatus includes a first capacitor and a processor in communication with the first capacitor. The first capacitor is configured to sense the capacitance of the fluid line at the first capacitor. The processor is configured to compare the sensed capacitance at the first capacitor with a reference capacitance to determine the composition of the fluid in the fluid line at the first capacitor. In some embodiments, the apparatus also includes a second capacitor. The second capacitor is configured to sense the capacitance of the fluid line at the second capacitor. The processor is configured to compare the sensed capacitance at the second capacitor with a reference capacitance to determine the composition of the fluid in the fluid line at the second capacitor.