Surface enhanced Raman scattering substrate assembly

1. A surface enhanced Raman scattering substrate assembly for detecting an analyte, the assembly comprising:

an etched fiber base;

a metallic nanoparticle coating disposed over at least a portion of an external surface of the etched fiber base, the metallic nanoparticle coating comprising metallic nanoparticles that have a largest dimension of 25 nm to about 500 nm; and

a needle circumscribing at least a portion of the etched fiber base.

2. The assembly of claim 1 , wherein the etched fiber base comprises stainless steel, copper, lead, chromium, tin, magnesium, aluminum, zinc, manganese, calcium, alloys thereof, or combinations thereof.

3. The assembly of claim 1 , wherein the metallic nanoparticle coating is disposed over about 50% to about 100% of the total surface area of the etched fiber base.

4. The assembly of claim 1 , wherein a surface area of the etched fiber base is greater than a corresponding fiber base that is free of etching.

5. The assembly of claim 1 , wherein the etched fiber base has a length ranging from about 3 cm to about 6 cm.

6. The assembly of claim 1 , wherein the etched fiber base has a width ranging from about 100 μm to about 400 μm.

7. The assembly of claim 1 , wherein the etched fiber base is substantially cylindrically shaped.

8. The assembly of claim 1 , wherein the metallic nanoparticles each independently comprise Ag 2 O, elemental silver, elemental gold, elemental copper, elemental platinum, mixtures thereof, alloys thereof, or combinations thereof.

9. The assembly of any one of claim 1 , wherein the metallic nanoparticles have a largest dimension of about 50 nm to about 100 nm.

10. The assembly of claim 1 , further comprising a metallic microparticle coating dispersed over at least a portion of the surface of the etched fiber base.

11. The assembly of any one of claim 1 , wherein the assembly is configured to detect the analyte in a gaseous phase, a liquid phase, a solid phase, or a combination thereof.

12. The assembly of claim 1 , further comprising:

an in-situ filter in the needle.

13. The assembly of claim 12 , wherein the in-situ filter comprises of cellulose, nitrocellulose, polytetrafluoroethylene (PTFE), nylon, polycarbonate, acrylic based polymers, methacrylic based polymers, and combinations thereof.

14. The assembly of claim 12 , wherein the in-situ filter is located in a tip of the needle.

15. The assembly of claim 12 , wherein the in-situ filter is located along one or more walls of the needle.

16. A method for detecting an analyte, the method comprising:

contacting an etched fiber base with a medium to collect the analyte from the medium on the etched fiber base, wherein a metallic nanoparticle coating is disposed over at least a portion of an external surface of the etched fiber base, the metallic nanoparticle coating comprising metallic nanoparticles that have a largest dimension of 25 nm to about 500 nm, wherein a needle circumscribes at least a portion of the etched fiber base;

contacting the etched fiber base comprising the analyte with an electromagnetic emission;

detecting the analyte; and

generating a spectrum.

17. The method of claim 16 , further comprising identifying or quantifying an analyte in the medium from the spectrum.

18. The method of claim 16 , wherein contacting the etched fiber base with the medium comprises puncturing a material with the needle to form an opening such that the etched fiber base collects the analyte from the medium.

19. A method of making an assembly comprising:

etching a fiber to form an etched fiber base;

coating metallic nanoparticles on an external surface of the etched fiber base, the metallic nanoparticle coating comprising metallic nanoparticles that have a largest dimension of 25 nm to about 500 nm; and

circumscribing at least a portion of the etched fiber base with a needle.