A liquid waveguide based evanescent wave sensor integrated onto a microfluidic chip

An evanescent wave sensor based on liquid waveguide is integrated onto a microfluidic chip. The structure of the liquid waveguide consists of three streams with two low refractive index fluids as cladding layers, which envelop a high refractive index fluid as a core layer along a microchannel. Light is coupled into the core layer, and a detected sample is injected into one cladding layer. The profile of the output light modal power is changed by varying the concentration of the sample. The sensor with a sensitivity of 275 μ m ² lmol can be used for real-time, low-cost, and label-free measurements in a wide range of applications.