Analyte permeable membrane systems for oxidative and optical stability
View Patent ↗A sensor that may be used to detect the presence, amount, and/or concentration of an analyte in a medium within an animal. The sensor may include a sensor housing, an indicator element embedded within and/or covering at least a portion of the sensor housing, and a membrane over the indicator element. The membrane may reduce indicator element deterioration by preventing immune cells, such as white blood cells, from contacting the indicator element, substantially prevent transmission of light of at least a specified wavelength or range of wavelengths through the membrane, and/or permit the analyte to pass through to the indicator element. The membrane may be an opaque diffusion membrane. The sensor may include a foil. The foil may block light and/or reduce indicator element deterioration. The membrane may reduce oxidation of the indicator element.
1. A sensor for in vivo detection of the presence, amount, and/or concentration of an analyte in a medium within a living animal, the sensor comprising:
a sensor housing;
an indicator element embedded within and/or covering at least a portion of the sensor housing; and
a porous, opaque diffusion membrane covering at least a portion of the sensor housing and a portion of the indicator element, wherein the diffusion membrane is configured to substantially prevent white blood cells from passing through the diffusion membrane and permit an analyte of interest to pass through the diffusion membrane to the indicator element and to substantially prevent transmission of light of at least a specified wavelength or range of wavelengths through the diffusion membrane;
wherein the diffusion membrane comprises a layer of hydrophilic material and a layer of torturous path material disposed over or under the layer of hydrophilic material, and the torturous path material is configured to provide a longer path through which reactive oxygen species produced by white blood cells would need to travel before reaching the indicator element.
2. The sensor of claim 1 , wherein the analyte is glucose.
3. The sensor of claim 1 , further comprising a layer.
4. The sensor of claim 3 , wherein the layer comprises platinum.
5. The sensor of claim 3 , wherein the layer is between the indicator element and the membrane.
6. The sensor of claim 5 , wherein the layer is a thin layer sputtered on the outside of the indicator element.
7. The sensor of claim 1 , wherein the indicator element is a polymer graft including indicator molecules.
8. The sensor of claim 1 , wherein the sensor housing includes a light source and a light detector.
9. The sensor of claim 1 , wherein the living animal is a human.
10. The sensor of claim 1 , wherein the medium is interstitial fluid.
11. The sensor of claim 1 , wherein the indicator element comprises a fluorescent indicator element.
12. The sensor of claim 1 , wherein the sensor housing comprises an optically transmissive polymer material.
13. The sensor of claim 1 , wherein the sensor housing is a shell.
14. The sensor of claim 1 , wherein the sensor housing is a capsule.
15. The sensor of claim 1 , wherein the diffusion membrane has pores configured to substantially prevent white blood cells from passing through the membrane but to permit glucose to pass through the membrane.
16. The sensor of claim 15 , wherein the diffusion membrane has a porosity of 3-60%.
17. The sensor of claim 15 , wherein pores formed through the diffusion membrane have a size of 0.45-6 microns.
18. The sensor of claim 1 , wherein the hydrophilic layer has a thickness of 10-200 microns.
19. The sensor of claim 1 , wherein the torturous path material comprises nylon.
20. The sensor of claim 1 , wherein the torturous path layer has a thickness of 50-200 microns.
21. The sensor of claim 1 , wherein the diffusion membrane comprises a layer of material selected from the group consisting of nylon, cellulose acetate, polytetrafluoroethylene, polyethylene teraphthlate, polypropylene, polyvinyl alcohol, polybutylene terephthalate, polyether ether ketone, polyanhydride, polyamide, polyvinylchloride, polyethersulfone, polyethylene terephthalate, polyvinylidene difluoride, polytetrafluoroethylene, nitrocellulose, acrylate, poly(methyl methacrylate), polyacrylate homo- or copolymers, polycarbonate, derivatives thereof, and combinations thereof.
22. The sensor of claim 1 , wherein the diffusion membrane has a thickness of 10-200 microns.
23. The sensor of claim 1 , wherein the diffusion membrane comprises an amount of opaque or light absorbing colorant such that light transmission through the diffusion membrane is reduced.
24. A sensor for in vivo detection of the presence, amount, and/or concentration of an analyte in a medium within a living animal, the sensor comprising:
a sensor housing;
an indicator element embedded within and/or covering at least a portion of the sensor housing; and
a porous, opaque diffusion membrane covering at least a portion of the sensor housing and a portion of the indicator element, wherein the diffusion membrane is configured to substantially prevent white blood cells from passing through the diffusion membrane and permit an analyte of interest and red blood cells to pass through the diffusion membrane to the indicator element and to substantially prevent transmission of light of at least a specified wavelength or range of wavelengths through the diffusion membrane, and the diffusion membrane comprises an opaque or light absorbing colorant.
25. The sensor of claim 24 , wherein the opaque or light absorbing colorant comprises TiO2 or carbon black.