A Broadband Biosensor Using Graphene-Metasurface Based Cross-Polarization Converter

• Published in: IEEE sensors journal 2022-07, Vol.22 (13), p.12820-12828
• Main Authors: Ghosh, Sambit Kumar, Chaudhuri, Anirban, Pal, Parama, Rai, Beena, Das, Santanu, Bhattacharyya, Somak
• Format: Article
• Language: English
• Subjects: Biomolecules; biosensing; Biosensors; Broadband; Circuits; Conversion ratio; Converters; Coronaviruses; Cross polarization; cross-polarization conversion; Figure of merit; figure of merit (FoM); Graphene; Graphene metasurface; Incident waves; Metasurfaces; Sensitivity; Sensors; Severe acute respiratory syndrome coronavirus 2; Silicon dioxide; Solvents
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2022.3176381

We present the design and analysis of a graphene metasurface-based cross polarization converter operating within the terahertz gap for detecting biomolecules over a broad spectral range, taking the SARS-CoV-2 virus as a specific example. To the best of our knowledge, our design reports the widest band of operation in the THz region of a graphene-based metasensor. Each meta-atom comprises a graphene pattern on silicon dioxide atop a continuous gold layer and exhibits near-unity cross polarization conversion ratio (PCR) and a 90% PCR bandwidth of 0.926 THz within the desired band (1.88 THz-2.81 THz). The proposed device demonstrates additional benefits which include a thin configuration ( \lambda /7.84) and compact lattice size ( \lambda /10.66), which are significantly better than other recently reported graphene metasurface biosensors. The device provides a sensitivity up to 490 GHz/RIU and a figure of merit (FoM) of 0.377 over a wide span of 0.926 THz within the terahertz gap. The electromagnetic response of this device has been validated via rigorous numerical analyses of simulated outputs as well as by developing a detailed circuit model representation of the same. The device demonstrates angular stability of nearly 40° under oblique incidence of the incident wave.