Multi-Modal surface plasmon polariton-raman scattering based bio-detection

Abstract

Methods and systems for combined SPP and Raman scattering-based bio-detection are provided. Embodiments include a bio-detection system having a microfluidics chip, a Surface Plasmon Polariton (SPP)-based system component, and a Raman scattering-based system component. The SPP-based and the Raman scattering-based system components can be used simultaneously or individually separately to detect biological and/or chemical analytes. The bio-detection system further includes an aerosol collector chip. Embodiments of the present invention can be used aboard means of propagation of biological and/or chemical analytes, including, for example, commercial aircrafts. Embodiments of the present invention can be used to enable an aircraft warning system.

1 . A microfluidics chip, comprising:
 an elastomer layer having fluidic channels constructed therein; and   a grating coupler coupled to said elastomer layer;   wherein said grating coupler includes a glass substrate coated with a gold layer, said gold layer etched to form a gold nanohole array and coated with bio-receptor molecules; and   wherein said bio-receptor molecules bind with analytes when present in fluid passed through said fluidic channels of said elastomer.   
     
     
         2 . The microfluidics chip of  claim 1 , wherein said elastomer layer includes a polydimethylsiloxane (PDMS) elastomer layer. 
     
     
         3 . The microfluidics chip of  claim 1 , wherein said gold nanohole array includes a two-dimensional array of regularly-spaced nanoholes. 
     
     
         4 . The microfluidics chip of  claim 1 , wherein said microfluidics chip is used within a Surface Plasmon Polariton (SPP)-based system that detects changes in SPP modes as a result of the binding of said bio-receptor molecules with said analytes. 
     
     
         5 . The microfluidics chip of  claim 1 , wherein said microfluidics chip is used within a Raman scattering-based system that detects changes in Raman-scattering intensity as a result of the binding of said bio-receptor molecules with said analytes. 
     
     
         6 . The microfluidics chip of  claim 1 , wherein said microfluidics chip is used within a combined Surface Plasmon Polariton (SPP)-based and Raman scattering-based system to detecting the binding of said bio-receptor molecules with said analytes. 
     
     
         7 . A bio-detection system, comprising:
 a microfluidics chip;   a Surface Plasmon Polariton (SPP)-based system that detects local refractive index changes within said microfluidics chip, wherein said local refractive index changes occur as a result of bio-receptor molecules within said microfluidics chip binding with analytes; and   a Raman scattering-based system that detects changes in intensity of Raman-scattered photons, wherein said Raman-scattered photons result from changes in vibrational, rotational or electronic energy of said bio-receptor molecules as a result of binding with said analytes.   
     
     
         8 . The bio-detection system of  claim 7 , wherein said microfluidics chip comprises:
 an elastomer layer having fluidic channels constructed therein; and   a grating coupler coupled to said elastomer layer;   wherein said grating coupler includes a glass substrate coated with a gold layer, said gold layer etched to form a gold nanohole array and coated with said bio-receptor molecules; and   wherein said bio-receptor molecules bind with analytes when present in fluid passed through said fluidic channels of said elastomer, thereby causing said refractive index changes at an interface between said gold layer and said fluidic channels (gold-liquid interface).   
     
     
         9 . The bio-detection system of  claim 8 , wherein said elastomer layer includes a polydimethylsiloxane (PDMS) elastomer layer. 
     
     
         10 . The bio-detection system of  claim 8 , wherein said gold nanohole array includes a two-dimensional array of regularly-spaced nanoholes. 
     
     
         11 . The bio-detection system of  claim 8 , wherein said SPP-based system comprises:
 a tunable laser that generates a laser beam to illuminate a surface area of said gold nanohole array, said laser beam having a wavelength and an angle of incidence relative to said microfluidics chip, wherein said wavelength is configured according to a spacing between adjacent nanoholes within said gold nanohole array to cause resonant excitation of surface plasmon polaritons that propagate along said gold-liquid interface.   
     
     
         12 . The bio-detection system of  claim 11 , wherein said SPP-based system further comprises:
 means for measuring a first energy associated with photons of said laser beam that interact with said surface plasmon polaritons; and   means for measuring changes in said first energy, wherein said changes in said first energy occur as a result of said local refractive index changes within said microfluidics chip.   
     
     
         13 . The bio-detection system of  claim 11 , wherein said SPP-based system further comprises:
 an orthogonally-crossed polarizer-analyzer pair including a polarizer and an analyzer;   wherein said gold nanohole array is located between said polarizer and said analyzer;   wherein said polarizer polarizes said laser beam according to a first polarization; and   wherein said analyzer filters out light polarized according to said first polarization, thereby only allowing resonant photons that result from interaction between said laser beam and said surface plasmon polaritons to pass through said analyzer.   
     
     
         14 . The bio-detection system of  claim 11 , wherein said laser beam further causes resonant excitation of surface plasmon polaritons that propagate along an interface between said gold layer and said glass substrate (gold-glass interface). 
     
     
         15 . The bio-detection system of  claim 14 , wherein said surface plasmon polaritons that propagate along said gold-glass interface are invariant to said refractive index changes that occur at said gold-liquid interface, wherein said SPP-based system further comprises:
 means for measuring a second energy associated with photons of said laser beam that interact with said surface plasmon polaritons that propagate along said gold-glass interface;   means for measuring changes in said second energy, wherein said changes in said second energy are due variations in temperature, pressure, and/or flow; and   means for calibrating said changes in said first energy according to said changes in said second energy, thereby reducing detection errors due to said variations in temperature, pressure, and/or flow.   
     
     
         16 . The bio-detection system of  claim 8 , further comprising an aerosol collector chip coupled to said fluidic channels, wherein said aerosol collector chip collects and concentrates aerosols into fluid which is passed through said fluidic channels. 
     
     
         17 . The bio-detection system of  claim 16 , wherein said aerosol collector chip collects aerosols from one or more of exhaled breath, air, water, and soil. 
     
     
         18 . The bio-detection system of  claim 8 , wherein said Raman scattering-based system comprises:
 a light source that generates a light having a first wavelength, wherein said light illuminates a surface area of said gold nanohole array; and   a spectrogram that generates a wavelength spectrum of photons scattered from said gold nanohole array as a result of said light and that detects scattered photons having a wavelength different than said first wavelength.   
     
     
         19 . The bio-detection system of  claim 18 , wherein said gold nanohole array causes hole-enhanced Raman scattering due to said light. 
     
     
         20 . The bio-detection system of  claim 18 , wherein said grating coupler causes surface-enhanced Raman scattering due to said light. 
     
     
         21 . The bio-detection system of  claim 7 , wherein said SPP-based system and Raman scattering-based system can be used simultaneously or individually separately. 
     
     
         22 . The bio-detection system of  claim 21 , wherein said SPP-based system and said Raman scattering-based system are substantially orthogonal to each other. 
     
     
         23 . The bio-detection system of  claim 21 , wherein said SPP-based system and said Raman scattering-based system are not substantially orthogonal, said bio-detection system further comprising:
 means for measuring correlation between said SPP-based system and said Raman scattering-based system; and   means for compensating for said measured correlation.   
     
     
         24 . The bio-detection system of  claim 7 , wherein said bio-detection system is usable within an aircraft warning system aboard an aircraft. 
     
     
         25 . The bio-detection system of  claim 8 , wherein each of said fluidic channels includes an array of sample wells. 
     
     
         26 . A method for bio-detection, comprising:
 directing light at a microfluidics chip;   detecting refractive index changes within said microfluidics chip, wherein said refractive index changes result when bio-receptor molecules within said microfluidics chip bind with analytes;   and   detecting Raman scattered photons that result from changes in vibrational, rotational, or electronic energy of said bio-receptor molecules when said bio-receptor molecules bind with said analytes.   
     
     
         27 . The method of  claim 26 , wherein said light includes a laser beam. 
     
     
         28 . The method of  claim 27 , further comprising:
 controlling said laser beam to generate a first surface plasmon polariton (SPP) mode along a gold-fluid interface of said microfluidics chip and a second SPP mode along a gold-glass interface of said microfluidics chip.   
     
     
         29 . The method of  claim 28 , wherein said step of detecting refractive index changes comprises:
 measuring a first energy associated with photons of said light that interact with surface plasmon polaritons that propagate along said gold-liquid interface; and   measuring changes in said first energy, wherein said changes in said first energy occur as a result of said refractive index changes within said microfluidics chip.   
     
     
         30 . The method of  claim 29 , wherein said first SPP mode varies when binding occurs between said bio-receptor molecules and said analytes, and wherein said second SPP mode is invariant to said binding. 
     
     
         31 . The method of  claim 30 , further comprising:
 measuring a second energy associated with photons of said light that interact with surface plasmon polaritons that propagate along said gold-glass interface;   measuring changes in said second energy, wherein said changes in said second energy are due to variations in temperature, pressure, and/or flow; and   calibrating said changes in said first energy according to said changes in said second energy, thereby reducing detection errors due to said variations in temperature, pressure, and/or flow.   
     
     
         32 . The method of  claim 26 , wherein said step of detecting Raman scattered photons comprises:
 generating a wavelength spectrum of photons scattered as a result of said light being directed at said microfluidics chip; and   detecting scattered photons having wavelengths different than a wavelength of said light.   
     
     
         33 . The method of  claim 26 , further combining detection results from said detecting steps to generate a bio-detection result, wherein said bio-detection result indicates the presence of analytes or lack thereof. 
     
     
         34 . The method of  claim 26 , wherein said bio-receptor molecules include one or more of complex carbohydrates, lectins, peptides, and anti-bodies. 
     
     
         35 . The method of  claim 34 , wherein said bio-receptor molecules are applied simultaneously to different areas of a gold layer of said microfluidics chip, and wherein each of said bio-receptor molecules is dedicated to detecting a respective analyte, thereby allowing multi-element bio-detection.