Spectral-phase 3D surface plasmon resonance imaging biosensor for COVID-19 neutralizing antibody detection

In this paper, we present a spectral-phase 3D surface plasmon resonance imaging biosensor for COVID-19 neutralizing antibodies detection. The optical design converts the sensitive light phase response at plasmonic resonance into spectral color information through polarization ellipse rotation. In the experiment, measurements on NaCl solution refractive index samples were carried, and the sensor resolution was found to be 2.3 × 10^-6 RIU. The sensor was further demonstrated for multiplex SARS-CoV-2 XBB.1 Omicron spike RBD antibodies detection. The bio-molecular detection limit was estimated to be 18.2 pg/ul, while the neutralizing antibodies concentration in a COVID-19 infected adult patient level is 179 ng/ml or 800 ng/ml according to the data of Office for National Statistics, UK. With further developments, the biosensor can find promising future commercial applications in COVID-19 vaccination development, disease control strategy design, and point-of-care disease detection.