Universal and flexible design for high-sensitivity and wide-ranging surface plasmon resonance sensors based on a three-dimensional tuning hypersurface

Surface plasmon resonance (SPR), generally including propagating SPR (PSPR) and localized SPR (LSPR), has attracted wide attention due to the uniqueness of the strong evanescent field. The PSPR has the merit of high sensitivity over the LSPR, but lacks flexibility to tune resonant wavelength and serves limited application. Here we revisit the fundamental PSPR wavevector matching theory and construct a three-dimensional (3D) tuning hypersurface for the parameters of resonant wavelength, incident angle, and surrounding refractive index, which provides the performance tuning guide map. With assistance of the hypersurface, a hypersurface-tuning PSPR (HT-PSPR) sensor is designed with high sensitivity and ultra-wide detection range. Experiments demonstrate that the sensor can selectively tune the resonance and render the sensitivity to a theoretical upper limit of ∼105 nm/RIU, or an ultra-wide detection range of 0.518 RIU, which satisfies the requirement for most gas and liquid sensing applications. Using D-biotin as the detection sample of small molecule (MW=244 Da), the HT-PSPR sensor achieves an ultra-low detection limit down to 27.5 fM. The hypersurface-tuning has created an intrinsic, universal and flexible method for tuning PSPR at the desired resonant wavelength, sensitivity and detection range, which is expected to find great significance in SPR design and applications.