Liquid jet waveguide for Raman spectroscopy

An optofluidic jet waveguide for Raman spectroscopy is reported. In this device a micro-channel is used to produce a high speed liquid stream acting at the same time, as the solution to analyse and as an optical waveguide. The liquid waveguide, exploiting total internal reflection, is able to effectively collect the Raman signal produced by the chemical compound under analysis opportunely excited by means of a laser source. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the Raman signal towards the detection system. The waveguiding nature of a liquid jet enables high Raman signal collection and the device configuration allows strong reduction of the background as no confining walls are used to contain the solution to analyse. The performances of the system have been successfully tested on isopropyl alcohol in water solutions showing a detection limit for this chemical compound of 0.8±0.1%.