  We report on the efficient design and fabrication of polymeric microracetrack
optical resonators for label-free biosensing purposes. Vertically-coupled
microresonators immersed in deionised water display high Q-factors (>35000) and
finesses up to 25. A surface sensing experiment performed with these
microresonators using 5-TAMRA cadaverine as a test molecule demonstrated both
the high sensitivity and low detection limit of our device.
