Fiber Optic Oxygen Probe with Gas Space Membrane
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Solution Overview
Problem
Existing fiber-optic oxygen probes are sensitive to environmental influences and yield inconsistent measurements, making it difficult to interpret oxygen content in biological tissues effectively.
Innovation Solution
A probe with an oxygen-permeable, liquid-impermeable membrane surrounding the distal fiber section creates a gas space that expands the measurement volume, reducing sensitivity to disruptive factors and allowing for a more accurate assessment of local oxygen supply, combined with a lock-in technique for enhanced robustness and a platinum or ruthenium complex as the oxygen-sensitive dye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fiber-optic oxygen probe is used for measuring oxygen content in biological tissue, then oxygen measurement is enabled, but the probe becomes sensitive to scattered light and environmental influences resulting in inconsistent measurements
Solution Approach 1:
An oxygen-permeable membrane is introduced as an intermediary between the biological tissue and the optical fiber sensor. This membrane allows oxygen to pass through while creating a stable gas space that isolates the fiber from direct contact with tissue, thereby eliminating sensitivity to scattered light and environmental influences while maintaining oxygen measurement capability
Solution Approach 2:
A flexible oxygen-permeable membrane is used to create a gas space surrounding the distal fiber section. This thin film structure allows oxygen diffusion while providing a stable measurement environment that reduces sensitivity to external disruptions, resolving the contradiction between measurement precision and reliability
2Reliability
If the measurement volume is expanded to improve local oxygen supply assessment, then measurement robustness increases, but the probe structure becomes more complex
Solution Approach 1:
A simple oxygen-permeable membrane is used to create the gas space, avoiding complex structural designs. The membrane naturally forms a barrier that defines the measurement volume while maintaining simplicity in the overall probe structure, thus increasing robustness without significantly increasing device complexity
3Measurement precision
If the distal fiber section is protected from direct tissue contact, then measurement consistency improves, but the oxygen diffusion path increases
Solution Approach 1:
A thin oxygen-permeable membrane is used to create the gas space, minimizing the diffusion distance for oxygen while still providing protection for the distal fiber section. The membrane thickness is optimized to allow sufficient oxygen diffusion while maintaining the protective barrier, thus resolving the contradiction between measurement consistency and diffusion path length
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 configuration provides a more reliable and consistent measurement of oxygen levels in biological tissues, improving the interpretation of results and enabling the assessment of local oxygen supply, while protecting the fiber optic sensor and allowing for measurements in various biological materials.
Implementation Method 1
The fluorescent dye is excited optically via the fiber, usually by laser radiation, which is tuned to the absorption bands of the dye. The dye molecules excited in this way go into the ground state with a time delay, e.g. in the range between 1 and 60 μs, emitting light of the same or red-shifted wavelength.
Implementation Method 2
Dynamic oxygen quenching is a well-known measurement technique for fiber-optic measurement of the partial pressure of the physically dissolved, i.e. free, oxygen. In the presence of oxygen, this transition can also take place without radiation into the ground state by collision processes. This reduces the intensity of the light reflected back through the fiber.
Implementation Method 3
The membrane protects the distal fiber section in the gas space, so that there is no risk of the measurement being disrupted. The creation of a gas space surrounding the distal fiber section by means of an oxygen-permeable and at the same time liquid-impermeable membrane
Data Source
Figure 1~3
Figure 4~6
Figure 5
AI summary
A probe (1) is used for measuring the oxygen content in biological tissue. The probe has at least one optical fibre (2) which, at the proximal end, can be coupled optically to a light source on the one hand and to a light sensor on the other. An oxygen-sensitive dye (5) is arranged on a distal end face of the fibre (2) and is coupled optically thereto. A distal fibre section (6), including the distal end face, is enclosed, together with the dye (5), by an oxygen-permeable and liquid-impermeable membrane (7) which defines, in the enclosed area, a gas space (8) surrounding the distal end face with the dye (5). The probe (1) is a component part of a catheter (14), which additionally comprises a temperature sensor (30) and, preferably, a pressure sensor (28). A probe is thus obtained in which the sensitivity of the fibre to outside interference at the measurement site is reduced and in which the possibilities of interpretation of the measurement results are improved.