A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing
Abstract Surface plasmon resonance (SPR) is a well-established technology for real-time highly sensitive label-free detection and measurement of binding kinetics between biological samples. A common drawback, however, of SPR detection is the necessity for far field angular resolved measurement of specular reflection, which increases the size as well as requiring precise calibration of the optical apparatus. Here we present an alternative optoelectronic approach in which the plasmonic sensor is integrated within a photovoltaic cell. Incident light generates an electronic signal that is sensitive to the refractive index (RI) of a solution via interaction with the plasmon. The photogenerated current is enhanced due to the coupling of the plasmon mode with Fabry-Pérot (FP) modes in the absorbing layer of the photovoltaic cell. The near field electrical detection of SPR we demonstrate will enable a new generation of cheap, compact and high throughput biosensors.