In this thesis, PDMS-based AWG microspectrometer for LOC application was demonstrated by foremost developing planar waveguide in PDMS material. The development of planar waveguide focused primarily in design and fabrication of novel PDMS waveguide with single-mode propagation as the basic building block for complex devices. By selecting the appropriate geometrical parameters, single-mode propagation can be generated even in a large cross section PDMS rib waveguide (> 5 μm). The fabrication of PDMS single-mode waveguide involved precise controlled of the slab and rib height to the accuracy of ±0.1 μm as well as the modification of the refractive index from 1.408 to 1.429. The characterization ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library VIII of the PDMS waveguide corroborated single-mode propagation at the wavelength of 635 nm with the propagation loss measured to be 0.48 dB/cm for low refractive index contrast waveguides (Δ=0.07%) and 0.2 dB/cm for high refractive index contrast waveguides (Δ=1.18%).