Monolithic Silicon-Based Photovoltaic-Nanoplasmonic Biosensor With Enhanced Limit of Detection and Minimum Detectable Power

On-chip, fully integrated electrical readout nanoplasmonic biosensors are suitable technology for the increasing demands of compact, portable, cost-efficient, and sensitive biosensors. In this paper, an ultra-compact photonic biosensor based on plasmonic nanostructure integrated with a PIN photovoltaic detector in a single chip is presented. The refractive index of different biosamples results in a shift in the surface plasmon resonance wavelength of the biosensor, and the PIN photovoltaic detector measures the intensity of transmitted light from the photonic structure at the plasmonic resonance wavelength. The biosensor shows a linear optical response of 354 nm/RIU and electrical sensitivity of about 16.9 mA/W.RIU for a wide range of biosamples. The PIN photovoltaic ultra-low dark current enables an extremely desirable limit of detection of 3 × 10
⁻⁸
RIU and minimum detectable power of −54 dBm for the biosensor. Moreover, a simple light-emitting diode is used as the light source in the biosensor's structure, which reduces its complexity and price by eliminating any extra optical setups and beam shapers. The presented structure is an important step forward for the realization of practical and handheld lab-on-chip nanophotonic biosensors, which leads to eliminating large clinical laboratories.