Lab-in-a-tube: on-chip integration of glass optofluidic ring resonators for label-free sensing applicationsElectronic Supplementary Information (ESI) available. See DOI: 10.1039/c2lc40275k

The fabrication of tubular rolled-up optofluidic ring resonators (RU-OFRRs) based on glass (SiO 2 ) material with high quality factors is reported. A novel methodology combining lab-on-a-chip fabrication methods and rolled-up nanotech is presented for the fabrication of fully integrated tubular optofluidic sensors. The microfluidic integration of several RU-OFRRs on one chip is solved by enclosing the microtubes with a patterned robust SU-8 polymeric matrix. A viewport on each microtube enables exact excitation and monitoring of whispering gallery modes with a photoluminescence spectroscopy system under constant ambient conditions, while exchanging the content of the RU-OFRR with liquids of different refractive indices. The refractrometric sensor capabilities are investigated regarding signal stability, sensitivity and reliability. The sensitivity of the integrated RU-OFRR, which is the response of the modes to the change in refractive index of the liquid, is up to 880 nm/refractive index units (RIU). A new assembly methodology combining lab-on-a chip fabrication techniques and rolled-up nanotech is presented to manufacture fully integrated optofluidic sensors on-chip based on tubular ring resonators made of glass material.