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Polymer microring resonators were demonstrated for sensing biomolecules without using fluorescent labels. The microring devices, fabricated by a direct imprinting technique, possess high Q factors of ∼20000. This feature provides high sensitivity and a low detection limit for biochemical sensing applications. With these properties, the devices were used to detect and quantify the biomolecules present either in a homogeneous solution that surrounds the microring waveguide (homogeneous sensing) or specifically bound on the waveguide surface (surface sensing). In the former sensing mechanism, the current devices can detect an effective index change of 10-7 refractive index units (RIU); in the latter, they can reach a detection limit of ∼250 pg/mm2 of biomolecular coverage on the microring surface. In addition, the experiments show that the devices can detect both small and large biomolecules.