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

Abstract

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.