SYSTEM AND METHOD FOR BREWSTER ANGLE STRADDLE INTERFEROMETRY

• US 20070076214A1
• Filed: 09/18/2006
• Published: 04/05/2007
• Est. Priority Date: 09/16/2005
• Status: Active Grant

• Current Assignee: University of Rochester
• Original Assignee: University of Rochester
• Inventors: Rothberg, Lewis
• Granted Patent: US 7,551,294 B2
• Time in Patent Office: Days
• US Class Current: 356/491
• CPC Class Codes: B01J 2219/00497 Features relating to the solid phase supports
• CPC Class Codes: B01J 2219/00527 Sheets
• CPC Class Codes: B01J 2219/00605 the compounds being directly bound or immobilised to solid supports
• CPC Class Codes: B01J 2219/00612 the surface being inorganic
• CPC Class Codes: B01J 2219/00626 Covalent
• CPC Class Codes: B01J 2219/00628 Ionic
• CPC Class Codes: B01J 2219/0063 Other, e.g. van der Waals forces, hydrogen bonding
• CPC Class Codes: B01J 2219/00637 by coating it with another layer
• CPC Class Codes: B01J 2219/00693 Means for quality control
• CPC Class Codes: B01J 2219/00707 separated from the reactor apparatus
• CPC Class Codes: B01J 2219/00722 Nucleotides
• CPC Class Codes: B01J 2219/00725 Peptides
• CPC Class Codes: C40B 60/12 for screening libraries
• CPC Class Codes: G01N 2021/7773 Reflection
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/75 Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated systems in which material is burnt in a flame or plasma G01N21/72, G01N21/73

Abstract

A system and method for biomolecular sensing are disclosed. The system includes a receptor for a target, a source of p-polarized light positioned to direct light toward the receptor in a manner effective to result in a condition of near perfect interference in the absence of target binding; and a detector positioned to measure any light reflected from the front and back surfaces of the coating. The receptor includes a substrate and a translucent coating on the substrate having front and back surfaces, wherein the incident angle for one of the substrate/coating interface and the medium/coating (probe) interface is greater than its Brewster angle and the incident angle for the other interface is less than its Brewster angle.

Claims

1. A sensor system for sensing at least one target in a medium, the system comprising:

a receptor for the at least one target, the receptor comprising a substrate and a translucent coating on the substrate having front and back surfaces;

a source of p-polarized light positioned to direct at least a portion of the p-polarized light from the source toward the coating on the receptor in a manner effective to result in a condition of near perfect interference in the absence of a target bound to the receptor, wherein the incident angle for one of the substrate/coating interface and the medium/coating interface is greater than its Brewster angle and the incident angle for the other interface is less than its Brewster angle; and

a detector positioned to measure the light reflected from the front and back surfaces of the coating, the detector identifying presence of at least one target based on the measured reflected light.

2. The system according to claim 1 wherein the incident angle for the substrate/coating interface is greater than its Brewster angle and the incident angle for the medium/coating interface is less than its Brewster angle.

3. The system according to claim 2 wherein ratio of substrate:

coating refractive indices is greater than 1 and the ratio of coating;

medium refractive indices is less than 1.

4. The system according to claim 1 wherein the incident angle for of the medium/coating interface is greater than its Brewster angle and the incident angle for the substrate/coating interface is less than its Brewster angle.

5. The system according to claim 4 wherein ratio of the substrate:

coating refractive indices is less than 1 and the ratio of the coating;

medium refractive indices is greater than 1.

6. The system according to claim 1 wherein the medium is an aqueous medium.

7. The system according to claim 6 further comprising at least one prism in a path of the at least a portion of the p-polarized light.

8. The system according to claim 1 wherein the medium is air.

9. The system according to claim 1 wherein the receptor is formed of silicon and the coating is a silicon oxide coating.

10. The system according to claim 9 wherein the silicon oxide coating is between about 1 and about 3 nm.

11. The system according to claim 9 wherein the silicon oxide coating is between about 2.2 and about 2.8 nm.

12. The system according to claim 9 wherein the silicon oxide coating is a native silicon dioxide coating of about 2.5 nm.

13. The system according to claim 1 wherein the coating has a thickness that is equal to mλ

(2n cos θ

) where m is an integer greater than zero, n is the refractive index of the coating, θ

is the angle of propagation from the normal in the coating, and λ

is the wavelength of the incident light.

14. The system according to claim 1 wherein the incident angle for the medium/coating interface is between about 71 degrees±

2 degrees in an aqueous medium.

15. The system according to claim 1 wherein the incident angle for the medium/coating interface is between about 75.5 degrees±

2 degrees in air.

16. The system according to claim 1 wherein the source of p-polarized light comprises:

a non-polarized light source and

a polarizer that induces p-polarization of at least a portion of light emitted by the non-polarized light source or reflected from the receptor.

17. The system according to claim 1 wherein the source of p-polarized light is a laser that emits substantially only p-polarized light.

18. The system according to claim 1 wherein the coating further comprises one or more adsorbates capable of recognizing the at least one target.

19. The system according to claim 18 wherein the one or more adsorbates are selected from the group of non-polymeric small molecules, polypeptides or proteins, oligonucleotides, and combinations thereof.

20. The system according to claim 18 wherein the coating further comprises a coupling agent that links the one or more adsorbates to the coating.

21. The system according to claim 1 wherein the light source is selected from the group of a laser, a light-emitting diode, and lamp comprising a narrow bandpass filter.

22. The system according to claim 1 wherein the detector is an imaging array, photomultiplier, CCD, or photodiode that captures an image of at least a substantial portion of the surface of the receptor.

23. The system according to claim 1 further comprising:

a control receptor having a coating that is identical to the coating on the receptor,

a first polarizer allowing substantially equal amounts of p- and s-polarized light incident on the control receptor;

a half wave plate positioned to phase flip p- and s-polarized light reflected from control receptor toward the receptor; and

a second polarizer allowing substantially equal amounts of p- and s-polarized light reflected from the receptor,

wherein in the absence of analyte binding the p-polarized light passed through the second polarizer is substantially null and in the presence of analyte binding a portion of p-polarized light is passed through the second polarizer.

24. The system according to claim 23 wherein the first and second polarizers are orthogonal or nearly orthogonal linear polarizers.

25. The system according to claim 23 wherein the first and second polarizers are circular polarizers.

26. A method for sensing at least one target, the method comprising:

providing a system according to claim 1;

directing p-polarized light at the receptor in a manner effective to achieve, in the absence of at least one target, a condition of near perfect interference between light reflected from the medium/probe interface and light reflected from the substrate/coating interface; and

measuring the light reflected from the interfaces of the receptor, wherein measurement of light reflected the interfaces indicates presence of the at least one target.

27. The method according to claim 26 further comprising:

providing an output identifying the at least one target based on the measured reflected light.

28. The method according to claim 26 wherein the coating further comprises one or more adsorbates capable of recognizing the at least one target.

29. The method according to claim 28 wherein the one or more adsorbates are selected from the group of non-polymeric small molecules, polypeptides or proteins, oligonucleotides, and combinations thereof.

30. The method according to claim 29 wherein the coating further comprises a coupling agent that links the one or more adsorbates to the coating.

31. The method according to claim 26 wherein the measuring the reflected light further comprises capturing an image of at least a substantial portion of the surface of the receptor.

32. The method according to claim 26 further comprising:

repeating said measuring before and after exposure of the receptor to a sample comprising the at least one target; and

comparing the measurement of reflected light from said measurements.

33. The method according to claim 32 further comprising:

quantifying the amount of at least one target present on the receptor.

34. The method according to claim 33 further comprising:

quantifying the concentration of the at least one target present in the sample.

35. The method according to claim 26 wherein the target is selected from the group of proteins, glycoproteins, peptidoglycans, carbohydrates, lipoproteins, lipoteichoic acids, lipid A, phosphates, nucleic acids, whole cells, virus particles, organic toxins, organic warfare agents.

36. The method according to claim 26 wherein said measuring occurs continuously over a predetermined period of time.

37. A method of inspecting a semiconductor wafer comprising:

performing the method of claim 26 on a semiconductor wafer, wherein said measuring is performed in one or more locations over a surface of the semiconductor wafer, wherein the measuring of reflected light indicates the presence of debris on the surface of the semiconductor wafer.

38. The method according to claim 37 wherein the semiconductor wafer is an unassembled semiconductor wafer.

39. The method according to claim 37 wherein the semiconductor wafer comprises a silicon substrate and a silicon dioxide coating.

40. The method according to claim 26 wherein the system further comprises:

a control receptor having a coating that is identical to the coating on the receptor,

a first polarizer allowing substantially equal amounts of p- and s-polarized light incident on the control receptor,

a half wave plate positioned to phase flip p- and s-polarized light reflected from control receptor toward the receptor, and

a second polarizer allowing substantially equal amounts of p- and s-polarized light reflected from the receptor;

and wherein said directing comprises passing substantially equal amount of p- and s-polarized light toward the control receptor, phase-flipping the s- and p-polarized light reflected from the control receptor toward the receptor, and passing the p- and s-polarized light reflected from the receptor through the second polarizer.