Plasmonic structures for phase-sensitive ellipsometry biosensing: a review

Plasmonic biosensing endeavors to offer the ultrasensitivity below 10 −7 RIU along with providing a label-free platform for the detection of biomarkers. Integrating the intensity (amplitude) sensing with phase property of light not only can increase the signal to noise ratio but also provides additional information of the phase changes compared to the conventional plasmonic technique. This information can be helpful for in-depth understanding of the biomolecular and cellular interactions of the sample. In this review, we aim to look into the recent works on plasmonic biosensing based on phase-sensitive ellipsometry technique and investigate the various structures that have been provided for this platform up to now. The structures based on thin films, colloids and disordered systems, nanoparticle/nanhole arrays, graphene and 3D structures have been reviewed. Undoubtedly, choosing a structural platform and optimizing its structural parameters can increase the biosensitivity as well as decreasing the limit of detection that plays a key role in biosensing. Due to the vast area of phase-sensitive plasmonics, we limit our focus to ellipsometry technique and its integration with plasmonics. We hope this review can open up new horizons towards the development and fabrication of highly sensitive plasmonic structures applicable in phase-sensitive biosensing.