Grooved Test Tube Stoppers for Headspace-Free Oxygen Sensing
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Solution Overview
Problem
Existing methods for sealing samples in test tubes and microtiter plates using an oil layer are inefficient, labor-intensive, and leave gaseous headspace that slows oxygen concentration detection, interfering with the interrogation of oxygen-sensitive photoluminescent probes.
Innovation Solution
A stopper and lid assembly formed from an oxygen barrier material with longitudinally extending grooves that create peripheral outlet channels, allowing fluid displacement without gaseous headspace, enabling efficient oxygen concentration measurement through optical interrogation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil layer is used to seal the sample, then the sample is sealed from fluid communication with the surrounding environment, but the detection of oxygen concentration changes is slowed due to gaseous headspace and the oil layer is not an effective oxygen barrier
Solution Approach 1:
The invention removes the gaseous headspace from the system by using a stopper that extends to the closed end of the test tube, eliminating the intermediate oxygen reservoir that slowed detection. The stopper creates direct contact between the sample and the sealed environment, allowing rapid oxygen concentration changes to be detected without the buffering effect of headspace gas.
Solution Approach 2:
The invention changes the physical state of the sealing interface by using a solid stopper material with oxygen barrier properties instead of an oil layer. This material parameter change provides both effective sealing and rapid oxygen concentration detection, eliminating the dual problems of poor oxygen barrier performance and slow detection associated with oil layers.
2Reliability
If an oil layer is used to seal the sample, then the sample is sealed from fluid communication, but the implementation is difficult to deploy consistently and is labor intensive
Solution Approach 1:
The invention employs a disposable stopper that is pre-formed and ready-to-use, eliminating the need for labor-intensive oil layer application. The stopper can be simply inserted into the test tube to provide reliable sealing, making the process quick, consistent, and easy to deploy without requiring skilled manual manipulation of oil layers.
3Reliability
If a stopper is inserted into the test tube cavity, then the sample is sealed and headspace is eliminated, but fluid displaced by the stopper insertion has nowhere to exit
Solution Approach 1:
The stopper incorporates porous material that allows trapped fluid to pass through it during insertion, eliminating the need for complex outlet channel structures. The porous nature of the stopper material provides inherent fluid egress pathways while maintaining the sealing function, simplifying the overall device design.
Solution Approach 2:
The stopper is constructed from composite material combining oxygen barrier properties with porous characteristics. This composite structure enables the stopper to simultaneously provide effective oxygen sealing and facilitate fluid displacement during insertion, resolving the contradiction between sealing effectiveness and fluid management complexity.
4Reliability
If the stopper has a convex distal end, then the stopper can effectively seal the cavity, but the optical path for interrogating photoluminescent probes may be interfered with
Solution Approach 1:
The stopper design incorporates a convex distal end only at specific locations where sealing is required, while maintaining optical transparency in the regions through which the optical path passes. This localized application of convex geometry allows the stopper to provide effective sealing at the cavity interface without interfering with the optical interrogation of photoluminescent probes in the sample.
Solution Approach 2:
The stopper material is selected to have appropriate optical transmission properties that allow excitation and emission light to pass through during photoluminescence-based oxygen sensing. This material parameter selection ensures that the sealing function does not compromise the optical measurement capability, enabling simultaneous achievement of reliable sealing and accurate oxygen concentration detection.
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 assembly effectively seals samples from fluid communication while allowing quick and easy implementation, maintaining efficient oxygen concentration detection without interference from gaseous headspace.
Implementation Method 1
stopper formed from an oxygen barrier material configured and arranged to longitudinally and sealingly project into a cavity of a test tube
Implementation Method 2
exposing the oxygen-sensitive photoluminescent material within the enclosed chamber to excitation radiation passed through the stopper to create excited oxygen-sensitive photoluminescent material, measuring radiation emitted by the excited oxygen-sensitive photoluminescent material through the stopper
Data Source
Figure 1
Figure 2
Figure 3~11
AI summary
An implement for eliminating headspace in the testing space(s) (T9 or MPWell) of a test tube (T) or microtiter plate (MP), and methods of using such implements to measure oxygen concentration in a test sample. The implement projects into a test chamber (T9 or MPWell) to displace a portion of a fluid sample within the test chamber (T9 or MPWell) and has longitudinally extending grooves (109 and 229) through which the displaced fluidic content can be discharged from the test chamber (T9 or MPWell).