Highly sensitive dual-functional all-dielectric biosensor for hemoglobin and cancer detection

Abstract

This paper is the first demonstration of a dual-functional metasurface (DFM) based on all-dielectric materials for biosensing applications. The proposed biosensor possesses a unique capability to switch between polarization conversion and absorber functionalities owing to the phase changing properties of VO₂. Accordingly, the sensor works in two modes: a highly sensitive reflective cross-polarization converter mode (4.38 - 5.08 THz) and an absorber mode (4.36 - 5.96 THz), both of which hold significant promise for the detection of hemoglobin and cancer cells, respectively. When VO₂ is in the insulating state, the reflective cross-polarization converter function of this biosensor exhibits exceptional sensitivity of 3.08 THz/RIU for hemoglobin detection. This is the highest sensitivity among the existing THz based biosensors. Likewise, the same biosensor transforms into an absorber when VO₂ is in the conducting state, offering an impressive sensitivity of 2.93 THz/RIU for detection of cancerous cells. The all-dielectric based DFM biosensor also provides a high degree of angular stability, providing stable response for incident angles of up to 60° for both its polarization converter and absorber functions.