High performance fluorescent optical sensor
View Patent ↗An optical sensor device for determining the presence or concentration of an analyte, contains a waveguide disposed over a light source and a light detector mounted on a surface of a substrate and separated by an internal baffle, wherein the waveguide has a thickness corresponding to a far field emission point of the light source as determined by a light shielding baffle between the light source and light detector. An analyte indicator matrix is disposed on the outer surface of the waveguide. The sensor device geometry takes advantage of only direct illumination of the indicator matrix, and direct collection of indicator matrix illumination, without any significant reflection by said waveguide. Undesirable light noise generated by the light source passes directly out of the device through the waveguide.
1. An optical sensor device for determining the presence or concentration of an analyte, comprising:
a substrate;
a light source for emitting light primarily of a preselected wavelength upon energization, mounted on a surface of said substrate;
a light detector for detecting light incident thereon and generating an electrical signal responsive thereto, mounted on said surface adjacent to said light source, and being separated therefrom by a light shielding baffle;
a waveguide formed over said light source and said light detector; said waveguide having a mean thickness corresponding to a far field emission point of said light source; and
an analyte-permeable indicator matrix disposed on an outer surface of said waveguide, said indicator matrix containing light-emitting indicator molecules whose light emission is attenuated or enhanced by the presence of analyte in said matrix, said indicator molecules being selected such that the wavelength emitted by the light source excites light emission in the indicator molecules;
wherein said light detector generates an electrical signal responsive to light incident thereon emitted by said indicator molecules.
2. An optical sensor device according to claim 1 , wherein said outer surface of said waveguide is substantially flat, and the thickness of said waveguide corresponds to said far field emission point of said light source.
3. An optical sensor device according to claim 1 , wherein said outer surface of said waveguide is in a curved arc configuration.
4. An optical sensor device according to claim 3 , wherein a focal point of said curved arc is outside of said sensing device.
5. An optical sensor device according to claim 1 , wherein undesired additional wavelengths emitted by said light source are caused to pass out of said waveguide without being substantially reflected thereby.
6. An optical sensor device according to claim 1 , wherein said sensing device is used to detect at least two different analytes.
7. An optical sensor device according to claim 1 , wherein said analyte-permeable indicator matrix is illuminated substantially solely by direct illumination from said light source.
8. An optical sensor device according to claim 1 , wherein said light detector collects substantially solely direct fluorescence illumination from said indicator matrix.
9. An optical sensor device according to claim 1 , wherein said light source is an LED.
10. An optical sensor device according to claim 1 , wherein said light detector is a photodiode.
11. An optical sensor device according to claim 1 , wherein said light-emitting indicator molecules are fluorescence molecules.
12. An optical sensor device according to claim 1 , wherein said baffle defines at least two cavities in which said light source and said light detector are located when mounted on said substrate, and said waveguide is formed over said cavities.
13. An optical sensor device according to claim 12 , further comprising a transparent fill-in material formed over said light source in the cavity in which said light source is located, wherein said transparent fill-in material has a refractive index that is substantially equal to the refractive index of said waveguide, such that said light source is in effect mounted within said waveguide.
14. An optical sensor device according to claim 12 , further comprising a color-doped fill-in material formed over said light source in the cavity in which said light source is located, wherein said color-doped fill-in material has a color corresponding to a peak wavelength emission of said light source.
15. An optical sensor device according to claim 12 , further comprising a color-doped fill-in material formed over said photodetector in the cavity in which said photodetector is located, wherein said color-doped fill-in material functions as a filter to block a predominant wavelength emitted by said light source from impinging on said photodetector.
16. An optical sensor device according to claim 13 , wherein said fill-in material is a polymeric material.
17. An optical sensor device according to claim 14 , wherein said fill-in material is a polymeric material.
18. An optical sensor device according to claim 15 , wherein said fill-in material is a polymeric material.
19. An optical sensor device according to claim 12 , further comprising a fill-in material formed over said light source in the cavity in which said light source is located, wherein said fill-in material has a refractive index that is lower than the refractive index of said waveguide.
20. An optical sensor device according to claim 15 , wherein said color-doped fill-in material has a refractive index that is higher than the refractive index of said waveguide.