Multiplex spectral-phase surface plasmon resonance 3D imaging biosensor

Abstract

In this paper, we demonstrate a spectral-phase surface plasmon resonance (SPR) imaging biosensor providing three-dimensional (3D) sensing information. The sensor probes the sensitive phase response at plasmonic resonance using stable spectral color profile. In the optical design, the plasmonic sensor surface is placed inside a polarizer pair with perpendicular polarization orientation. The polarizer pair originally does not allow excitation light to pass through. At plasmonic resonance, the differential phase response between p- and s-polarization light rotates the polarization ellipse, which allows the excitation light to leave the polarizer cavity. Furthermore, the differential phase response is wavelength dependent and a phase-spectral color profile is created at the SPR image. The spectral-phase color profile is not sensitive to environmental vibration comparing to conventional interferometric phase SPR detections. The sensor does not require phase modulation either in the spatial or time domain, which enables the spectral-phase SPR sensor to provide 3D information in the x, y and time dimensions in real-time.

In the experiment, refractive index sample measurements were performed for different concentrations of NaCl solutions between 1.3330 and 1.3455 RIU. The RI sensor resolution was found to be 2.16 × 10⁻⁵ RIU. In biosensing experiment, multiplex array detection was demonstrated in monitoring of eight bovine serum albumin (BSA) antigen-antibody molecular binding interactions in parallel. Experimental results showed that the sensor detection limit was 41.7 ng/ml, which was corresponding to a molarity detection limit of 613.2pM for BSA antibodies. The multiplex spectral-phase SPR 3D imaging biosensor can find promising applications in high-throughput biomarker detections, drug discovery and food safety monitoring.