A compact and multichannel optical biosensor based on a wavelength interrogated input grating coupler

The design, fabrication and characterization of a compact optical biosensor based on an input grating coupler are presented. The sensor device consists of a waveguide-integrated single grating structure. The optical reader is based on the use of a largely tunable, small footprint infrared laser for wavelength interrogation of the sensor and on edge-detection of waveguided modes, resulting in a compact configuration. A multiplexing approach is illustrated and a two-output sensor system is demonstrated. The device is packaged in a microfluidic cartridge for sample handling. The volumetric sensing performance of the system is characterized and a limit of detection of 1 × 10−5 RIU is reported while the surface sensing capability is demonstrated by detection of protein diluted down to 200 ng/ml.