Sensor for tissue gas detection and technique for using the same
View Patent ↗A sensor for carbon dioxide detection may be adapted to have reduced water permeability. A sensor is provided that is appropriate for use in an aqueous medium. The sensor has a barrier with reduced water permeability, but that is permeable to carbon dioxide, that separates the sensor components from the aqueous medium.
1. A sensor comprising:
a porous substrate being permeable to water and carbon dioxide and having a first surface and a second surface, the first surface being adapted to be placed on mucosal tissue of a patient to obtain a sample;
a selective barrier being permeable to carbon dioxide and substantially impermeable to water, the selective barrier being disposed on the second surface of the porous substrate; and
a solid indicator disposed on the selective barrier opposite the porous substrate, the solid indicator being adapted to provide feedback related to a presence of carbon dioxide in a non-gaseous portion of the sample.
2. The sensor, as set forth in claim 1 , wherein the selective barrier has a ratio of water permeability to carbon dioxide permeability of less than 10.
3. The sensor, as set forth in claim 1 , comprising an optically transparent layer or an optically opaque layer disposed on the indicator opposite the selective barrier.
4. The sensor, as set forth in claim 1 , comprising a holder adapted to hold the sensor adjacent to the mucosal tissue.
5. The sensor, as set forth in claim 1 , wherein the indicator comprises a carbon dioxide-sensitive chemical compound.
6. The sensor, as set forth in claim 1 , wherein the selective barrier comprises a polymer film.
7. The sensor, as set forth in claim 6 , wherein the polymer film comprises pores less than 5 microns in diameter.
8. The sensor, as set forth in claim 1 , wherein the selective barrier comprises a polytetrafluoroethylene layer.
9. A system comprising:
a monitor; and
a sensor adapted to be operatively coupled to the monitor, the sensor comprising:
a porous substrate being permeable to water and carbon dioxide and having a first surface and a second surface, the first surface being adapted to be placed on mucosal tissue of a patient to obtain a sample;
a selective barrier being permeable to carbon dioxide and substantially impermeable to water, the selective barrier being disposed on the second surface of the porous substrate; and
a solid indicator disposed on the selective barrier opposite the porous substrate, the solid indicator being adapted to provide feedback related to a presence of carbon dioxide in a non-gaseous portion of the sample.
10. The system, as set forth in claim 9 , wherein the selective barrier has a ratio of water permeability to carbon dioxide permeability of less than 10.
11. The system, as set forth in claim 9 , comprising an optically transparent or an optically opaque layer disposed on the indicator opposite the selective barrier.
12. The system, as set forth in claim 9 , comprising a holder adapted to hold the sensor adjacent to the mucosal tissue.
13. The system, as set forth in claim 9 , wherein the indicator comprises a carbon dioxide-sensitive chemical compound.
14. The system, as set forth in claim 9 , wherein the selective barrier comprises a polymer film.
15. The system, as set forth in claim 14 , wherein the polymer film comprises pores less than 5 microns in diameter.
16. The system, as set forth in claim 9 , wherein the selective barrier comprises a polytetrafluoroethylene layer.
17. A method comprising:
taking a patient sample by contacting a mucosal tissue of a patient with a porous substrate that is permeable to water and carbon dioxide, wherein the porous substrate is disposed on a sample-contacting surface of a selective barrier;
contacting the patient sample with the sample-contacting surface of the selective barrier, wherein the selective barrier is permeable to carbon dioxide and substantially impermeable to water; and
contacting a carbon dioxide-containing portion of the patient sample with a solid indicator layer disposed on a surface of the selective barrier opposite the sample-contacting surface, wherein the indicator is adapted to provide feedback related to a presence of carbon dioxide.
18. The method, as set forth in claim 17 , wherein the selective barrier has a ratio of water permeability to carbon dioxide permeability of less than 10.
19. The method, as set forth in claim 17 , comprising assessing the presence of carbon dioxide by viewing the indicator through an optically transparent layer.
20. The method, as set forth in claim 17 , wherein the indicator changes color in response to the presence of carbon dioxide.
21. A method of providing a sensor, comprising:
providing a solid indicator layer adapted to provide feedback related to a presence of carbon dioxide in a non-gaseous patient sample;
providing a selective barrier disposed on a sample-contacting side of the indicator, wherein the selective barrier is permeable to carbon dioxide and substantially impermeable to water; and
providing a holder adapted to hold the selective barrier against and in direct contact with a mucosal tissue.
22. The method, as set forth in claim 21 , comprising:
providing an optically transparent layer or an optically opaque layer disposed on the indicator.
23. The method, as set forth in claim 21 , wherein the selective barrier substantially surrounds the indicator.
24. The method, as set forth in claim 21 , comprising:
providing a porous substrate that is permeable to water and carbon dioxide, wherein the porous substrate is disposed on the sample-contacting surface of the selective barrier.
25. The method, as set forth in claim 21 , wherein the indicator comprises a carbon dioxide-sensitive chemical compound.
26. The method, as set forth in claim 21 , wherein the selective barrier comprises a polymer film.
27. The method, as set forth in claim 26 , wherein the polymer film comprises pores less than 5 microns in diameter.
28. The method, as set forth in claim 21 , wherein the selective barrier comprises a polytetrafluoroethylene layer.
29. The method, as set forth in claim 21 , wherein the selective barrier has a ratio of water permeability to carbon dioxide permeability of less than 10.