SiN-microring-resonator-based optical biosensor for neuropeptide Y detection

We report the design, fabrication, and characterization of a silicon-nitride (SiN) microring-resonator-based label-free biosensor for the purpose of neuropeptide Y (NPY) protein detection. NPY is commonly associated with stress in human body. The device uses evanescent field sensing, its geometry is optimized for 1550-nm signal, and it is fabricated by following standard CMOS processes. Top surface of the device is designed to function in aqueous environment and appropriately functionalized to ensure the biomaterial-specific attachment. The time-dependent spectral response to the biomaterial attachment is observed by scanning a tunable laser source around 1550 nm and measuring the resonance shift in the transmission spectrum. We experimentally achieve the detection into nanomolar concentration level in a regular assay system with 0.1 nm/(μg/mL) of sensitivity and ~ 30 mins of analysis time. This sensitivity is further amplified by a factor of three with a sandwiched assay technique, with which ~ 58 nM (0.25 μg/mL) concentration of NPY is successfully detected.