CO2 Optical Sensor for Microorganism Detection in Pigmented Samples
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Solution Overview
Problem
Existing methods for detecting and enumerating microorganisms in opaque and highly pigmented samples, such as colored beverages and gelatin capsules, are inadequate due to interference from pigments and the instability of agar-based systems, which also limit their use in clinical sterility tests and enumeration.
Innovation Solution
A device with a transparent container featuring a crosslinked polymer matrix sensitive to carbon dioxide, allowing for optical detection of microorganism growth through light transmission, enabling the detection and enumeration of microorganisms in highly pigmented samples and ensuring stability for clinical use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a semi-liquid phase (agar) is used for optical detection, then optical transmittance can be measured, but the agar disintegrates at higher temperatures and cannot be thermally sterilized
Solution Approach 1:
The patent changes the physical state parameter of the detection medium from semi-liquid agar to a solid matrix. This parameter change allows the system to withstand thermal sterilization temperatures while maintaining optical detection capabilities through the solid matrix.
Solution Approach 2:
The patent uses a composite structure combining a solid matrix material with agar or other growth media. This composite allows the solid matrix to provide thermal stability and structural integrity for sterilization, while the embedded agar or media maintains biological functionality for microbial growth and optical detection.
2Adaptability or versatility
If pigments are present in the sample, then the sample can be tested, but the pigments diffuse into the semi liquid phase and mask the optical readings
Solution Approach 1:
The patent introduces a solid matrix as an intermediary barrier between the pigmented sample and the optical detection path. This matrix allows optical light to pass through while preventing pigment molecules from diffusing into the detection phase, thus maintaining measurement accuracy in pigmented samples.
Solution Approach 2:
The patent segments the detection system into distinct phases: a solid matrix phase for optical detection and a separate liquid phase for sample incubation. This segmentation prevents mixing of pigments with the optical detection medium while maintaining functionality of both systems.
3Measurement precision
If agar is used in the detection system, then optical readings can be performed, but the agar occasionally gets dislodged during shipping, particularly when exposed to low and freezing temperatures
Solution Approach 1:
The patent changes the physical state parameter from semi-liquid agar to a solid matrix structure. This parameter change provides structural rigidity and stability that prevents dislodging during shipping and exposure to freezing temperatures, while maintaining optical transparency for readings.
4Reliability
If an opaque silicone based optical indicator matrix is used, then the sensor is separated from the specimen and growth media, but the device is slow in reacting to CO2 generation and requires reflectance measurement
Solution Approach 1:
The patent uses a gas-permeable membrane as an intermediary that allows rapid CO2 diffusion from the specimen to the indicator matrix. This membrane intermediary maintains sensor separation for reliability while enabling fast CO2 transport for rapid detection response.
Solution Approach 2:
The patent employs a porous or gas-permeable matrix structure that allows efficient gas diffusion. This porous structure accelerates CO2 transport compared to opaque silicone, enabling faster detection while maintaining the benefits of sensor separation and stability.
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 solution provides reliable detection and enumeration of microorganisms in opaque samples, overcoming the limitations of previous methods by using a transparent matrix that is stable under sterilization and resistant to interference, allowing for precise optical measurements and rapid detection of CO2 production.
Implementation Method 1
The matrix is a crosslinked polymer which facilitates penetration of light and allows for detection of interactive light produced when external light aimed through the container interacts with a carbon dioxide sensitive indicator reagent embedded within the matrix
Implementation Method 2
at least one indicator reagent sensitive to carbon dioxide gas generated by the microorganisms in the incubation zone with the generated carbon dioxide gas diffusing into the matrix in the detection zone
Implementation Method 3
The matrix of the detection zone is configured to facilitate penetration of external light aimed at the transparent section of the container through the matrix and interaction of the external light with the indicator reagent to yield interactive light that escapes through the transparent section of the container
Data Source
AI summary
A new device and method for detecting the presence of living microorganisms in test samples are described. The device includes a container having at least one section transparent to light with an incubation zone defined in the container, the incubation zone containing growth media in which the sample is cultured. A detection zone containing a matrix composed of a polymeric material which is substantially transparent to light, and at least one indicator reagent sensitive to carbon dioxide gas generated by the microorganisms in the incubation zone is located in the transparent section of the matrix. The matrix is configured to facilitate penetration of external light aimed at the transparent section of the container and interaction of the external light with the indicator reagent to yield interactive light that escapes through the transparent section of the container, said interactive light is being indicative of the presence and/or concentration of the microorganisms.