GRATING-BASED EVANESCENT FIELD MOLECULAR SENSOR USING A THIN SILICON WAVEGUIDE LAYER
First Claim
1. A molecular sensor comprising:
- a silicon on insulator (SOI) wafer including a single crystal silicon layer waveguide over a SiO2 insulator layer, the waveguide having a diffraction grating on a sensor surface which is functionalized with receptors for a specific target molecule;
such that the grating couples a polarized beam of light incident the sensor surface to excite preferentially a single mode in the waveguide and equally couples the single mode from the waveguide to form a sensed output signal; and
the waveguide has a thickness of 10-400 nm, selected so that an overlap integral of the waveguide'"'"'s mode intensity over the functionalized sensor surface is greater than 50% of the overlap integral over any other region of the same thickness within the waveguide.
1 Assignment
0 Petitions
Accused Products
Abstract
A technique for high sensitivity evanescent field molecular sensing employs a detection scheme that simultaneously couples a polarized beam to a single mode of a waveguide, and couples the polarized beam out of the waveguide to specularly reflect the beam by the same grating. Strong interaction with the single (preferably TM) mode is provided by using a silicon on insulator (SOI) wafer having a waveguide thickness chosen between 10-400 nm so that the majority of the mode field strength spans the evanescent field. Well known, robust techniques for producing a grating on the waveguide are provided. Interrogation from a backside of the SOI wafer is taught.
-
Citations
23 Claims
-
1. A molecular sensor comprising:
a silicon on insulator (SOI) wafer including a single crystal silicon layer waveguide over a SiO2 insulator layer, the waveguide having a diffraction grating on a sensor surface which is functionalized with receptors for a specific target molecule;
such that the grating couples a polarized beam of light incident the sensor surface to excite preferentially a single mode in the waveguide and equally couples the single mode from the waveguide to form a sensed output signal; and
the waveguide has a thickness of 10-400 nm, selected so that an overlap integral of the waveguide'"'"'s mode intensity over the functionalized sensor surface is greater than 50% of the overlap integral over any other region of the same thickness within the waveguide.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
17. A method of sensing a target molecule if present, within a fluid flow, the method comprising:
-
providing a silicon on insulator (SOI) wafer including a single crystal silicon layer waveguide over a SiO2 insulator layer, the waveguide having a diffraction grating on a sensor surface that is functionalized with receptors for a specific target molecule; applying the fluid flow to the sensor surface so that if the target molecule is present, it will preferentially attach to the receptors; applying a polarized beam of light incident the sensor surface so that the diffraction grating couples the beam to excite preferentially a single mode in the waveguide and equally couples the single mode from the waveguide to form a sensed output signal, the waveguide having a thickness of 10-400 nm, selected so that an overlap integral of the waveguide'"'"'s mode intensity over the functionalized sensor surface is greater than 50% of the overlap integral over any other region of the same thickness within the waveguide; and determining a property of the sensed output that varies with interaction of the evanescent field with the target molecules if present. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
Specification