Laser Interferometry Tube Pressure Measurement
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Solution Overview
Problem
Existing methods for determining tube pressure in extracorporeal blood treatment systems, such as those used in dialysis, face challenges including contact issues with blood, complexity, and high costs, particularly with air column and pressure dome designs, which can lead to patient safety risks and equipment damage.
Innovation Solution
A contactless method using laser interferometry, specifically laser speckle interferometry, to measure tube pressure by detecting changes in the tube's surface expansion, allowing for accurate pressure determination without direct contact with the fluid or additional complex components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air column method is used for pressure measurement, then pressure can be detected, but blood contact with air activates clotting functions and risks patient safety
Solution Approach 1:
The patent replaces mechanical contact-based pressure measurement (air column, pressure dome) with optical measurement using laser interferometry. The laser beam measures tube surface displacement caused by pressure changes without contacting the blood, eliminating clotting activation while maintaining measurement precision.
Solution Approach 2:
The patent introduces the tube wall as an intermediary element. The laser measures the external surface of the tube, which deforms in response to internal pressure changes. This intermediary allows indirect pressure measurement without breaking the closed blood system or introducing air contact.
2Measurement precision
If pressure dome with membrane is used, then pressure can be measured, but additional complex components increase device complexity and production cost
Solution Approach 1:
The patent extracts the measurement function from physical contact components and implements it through optical field interaction. By taking out the need for air columns, membranes, and pressure domes, the system achieves pressure measurement using only the existing tube and laser interferometry equipment.
Solution Approach 2:
The patent creates an optical copy or representation of the pressure effect through laser interferometry. The interference pattern of laser light serves as a copy of the physical displacement caused by pressure, allowing measurement without physical sensors in the blood path.
3Measurement precision
If traditional pressure measurement components are used, then pressure detection is possible, but risk of equipment damage increases
Solution Approach 1:
The patent replaces fragile mechanical components (membranes, pressure domes) with robust optical measurement. The laser interferometry system has no moving parts or contact elements that can be damaged by high pressures, significantly improving equipment reliability while maintaining measurement precision.
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 pressure measurement within the tube without compromising patient safety, eliminating the need for additional components and reducing the risk of equipment damage, while maintaining measurement precision through fixed but releasable tube arrangements and advanced image analysis.
Implementation Method 1
A first aspect of the present invention relates to a method of observing a changing surface by means of laser interferometry, in particular by means of laser speckle interferometry
Implementation Method 2
wherein the changing surface is preferably a surface of a tube and the method is used to determine the pressure in the tube
Implementation Method 3
This method exploits the fact that the surface of a flexible/elastic tube changes when the pressure in the tube changes. For example, the tube stretches as the pressure in the tube increases, whereby the diameter of the tube increases and the surface of the tube is expanded
Data Source
AI summary
The present invention relates to a method of observing a changing surface by means of laser interferometry, in particular by means of laser speckle interferometry, wherein the changing surface is preferably a surface of a tube and the method is used to determine the pressure in the tube. A further aspect of the invention relates to a corresponding apparatus.