Label-free biosensor array based on silicon-on-insulator ring resonators addressed using a WDM approach

We report a silicon-on-insulator ring resonator biosensor array with one output port, using wavelength division multiplexing as the addressing scheme. With the use of on-chip referencing for environmental drift cancellation, simultaneous monitoring of multiplexed molecular bindings is demonstrated, with a resolution of $0.3\mathrm{pg}/{\mathrm{mm}}^2$ ($40\mathrm{ag}$ of total mass) for protein concentrations over 4 orders of magnitude down to $20\mathrm{pM}$. Reactions are measured over time periods as long as $3\mathrm{h}$ with high stability.