Integrated waveguide with a microftuidic channel in spiral geometry for spectroscopic applications

摘要

The authors fabricated and tested a compact optical sensor with an integrated waveguide and a microchannel in spiral geometry. The multimode waveguide, consisting of an SU-8 core of 40 μm thick and 50 μm wide and a fluid cladding layer of 60 μm thick, realizes a light-fluid interaction length of 110 mm within a device area of 4 cm~2. The waveguide sensor measures changes in liquid sample concentration and is sensitive to changes in liquid refractive index. Absorbance measurements using the spiral waveguide sensor demonstrate increased sensitivity compared with a linear geometry sensor.