A micro-sensor based on selenide glasses for evanescent wave detection in mid-infrared spectral range was designed and fabricated. Ge-Sb-Se thin films were successfully deposited by radio-frequency magnetron sputtering. In order to characterize them spectroscopic ellipsometry, atomic force microscopy and contact angle measurements were employed to study near and middle infrared refractive index, surface roughness and the wettability, respectively. Selenide sputtered films were micro-patterned by means of reactive ion etching with inductively coupled plasma process enabling single-mode propagation at a wavelength of 7.7 µm for a waveguide width between 8 and 12 µm. Finally, optical waveguide surface was functionalized by deposition of a hydrophobic polymer, which will permit detection of organic molecules in water. Thus, the optical transducer is a ridge waveguide composed by cladding and guiding Ge-Sb-Se sputtered layers exhibiting a tailored refractive index contrast and a polymer layer onto its surface ready for environmental detections in middle infrared.