Inline integration of offset MMF-capillary-MMF structure as a portable and compact fiber-optic surface-enhanced Raman scattering microfluidic chip.

Abstract

A novel fiber-optic surface-enhanced Raman scattering (SERS) microfluidic chip integrated with an embedded Raman probe is presented and demonstrated. The Raman probe consists of the offset-multimode-fiber (MMF)-capillary-MMF (OMCM) structure and SERS substrate. The probe is embedded in the microfluidic channel to form a compact and portable chip. The chip is employed with a fiber coupler in an all-fiber detection system, which has a good stability compared to the free space focusing by the conventional confocal Raman microscope. The excitation light transmits from both ends of the OMCM probe into the capillary, and the generated Raman scattered signals are collected by two MMFs simultaneously. Experimental results of the Rhodamine 6G (R6G) detection show that the Raman signal intensity increases in a linear pattern at ∼1509 cm-1 with the increase of R6G concentrations. This kind of chip is compact, integrated, and miniaturized for the Raman signal detection. Furthermore, it can be fabricated easily in large quantities at cost, rendering promising applications.