Highly-Enhanced Plasmonic Biosensors based on Atomically Thin Two-Dimensional Chalcogenide Phase-change Materials

Abstract : We designed an enhanced plasmonic sensing device based on 2D Ge2Sb2Te5 phase change nanomaterials. The sensing capability has been experimentally demonstrated to be 7000,000 μm/RIU with a detection limit of 10 fM for BSA molecules. © 2020 The Author(s) 1. Introduction Surface plasmon resonance (SPR) sensors have been exploited as an effective tool for real-time and label-free biochemical detection over these years [1]. They are used to detect the optical signal change in the reflected light beam at the sensing interface where surface plasmon polaritons are excited by the incident light. This signal change is strongly dependent on the evanescent field perturbation induced by the molecular binding at the plasmonic interface. However, the sensitivity of those sensors is not able to detect target analytes with low molecular weight (less than 400 Dalton) by the conventional angular scanning method. To overcome this challenge, we proposed an enhanced plasmonic sensing technique through the phase singularity-related Goos-Hänchen (GH) interrogation method with an enhanced zero-reflection performance by the atomically thin phase change nanomaterials [2-4]. We constructed an optimized multi-layered metallic sensing substrate based on GST and gold thin film. Experimental results show that the sensitivity in Goos-Hänchen (GH) shift has been greatly enhanced compared to pure gold substrate by more than one order of magnitude. Bovine serum albumin (BSA) molecules with low concentrations ranging from 10 fM to 10 μM have been successfully detected. Thus, we believe that this device has great potential in detecting chemical and biological reactions with ultra-high sensitivity especially for the clinical diagnostic usages.