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Optical cavities are considered promising devices for biosensing to satisfy the high demands of the growing proteomics market. We present a prototype sensor for multiplexed label-free monitoring of biomolecular interactions based on an array of three-by-four silicon-on-insulator microring resonators fabricated by standard complementary metal-oxide semiconductor (CMOS) technology. Parallel readout was performed with an infrared camera. We have demonstrated the simultaneous detection of several model antibodies in a highly specific way. For that, we integrated the optical chip with low-temperature polydimethylsiloxane (PDMS) packaging, enabling excellent compatibility with the receptor molecules. We obtain a very selective biomolecular interaction by grafting a 2.5-nm poly(ethylene glycol) layer to the silicon. Using silicon on insulator as the material platform offers high sensitivity through miniaturization and low-cost mass fabrication through standard CMOS technology steps. The sensors in this interrogation method are able to detect 3.4 pg/mm2 of a protein overlayer or a theoretical total mass of about 74 ag. For this novel lab on a chip, the fabrication, chemistry, readout, and packaging are developed to be scalable to detect hundreds of affinity interactions within several minutes.
Date of Publication: Oct. 2009