Integrated optical sensor array for biochemical multiparameter analysis
In this paper we demonstrate the ability to analyze a multiple of miniaturized bus-integrated sensor elements at high sensitivity from the superimposed complex overall spectrum by individual frequency modulation of optical microring resonators (MRR) fed by a single bus waveguide. The diverse sensor elements can be coated with biochemically selective adlayers (e.g., antibody molecules) to specifically promote the accumulation of target molecules on the MRR surface. Adhesion of target molecules results in an increase of the MRR resonance frequencies which can be measured at high sensitivity with a picometer accuracy. Readout of each MRR from the complex overall spectrum is performed by using phase sensitive lock-in detection to filter out the individual and selective response to external stimuli. We fabricated test arrays with 12 MRR elements based on silicon nitride material, each element integrated with a heater electrode for thermo-optical modulation of the MRR. A clea r readout of the individual MRR by using a tuneable laser source is accomplished in a simple and reliable manner via lock-in detection despite strong overlap of the individual resonances. With our first results, we point out the large potential for multiplexed label-free detection of diverse biomolecular compounds.