Nanoplasmonic biosensing with on-chip electrical detection.

A nanoplasmonic biosensor chip with integrated electrical detection is presented. The concept is based on the local refractive index sensitivity of nanoplasmonic gold nanodisks (110 nm in diameter and 20 nm in height) that are fabricated, through a parallel method, directly on an array of silicon solar cells or photoactive diodes. The nanoplasmonic properties of the sensor chip were investigated both optically and electrically, with excellent agreement between the two. We show that local changes in the refractive index of the surrounding environment gives changes in the nanoplasmonic properties of the gold nanodisks, which induce corresponding changes in the photocurrent at single wavelengths of the nanoplasmonic solar cells. With a simple light-emitting diode as light source, and together with a material-specific modification protocol, the photocurrent output of the nanoplasmonic sensor chip was successfully used to monitor a specific biorecognition reaction in real-time.