Metasurface-based antennas integrated with carbon nanotubes for DNA sensors applications

This paper presents the design, fabrication, and characterization of two types of microstrip patch antennas: the first one (A1) incorporates four complementary split ring resonators (CSRRs), whereas the second one (A2) is a conventional microstrip patch antenna with a so-called defect ground plane, which embeds four CSRRs etched in the back reflector. The CSRRs incorporated inside the patch (A1) give a major contribution to the performance of the antenna. The simulation results show an improvement of the reflection coefficient $\vert\mathrm{S}_{11}\vert$ from −20 dB to −38 dB for A2, and of the directivity from 4.68 dBi to 5.68 dBi when considering A1. The paper also proposes the fabrication of a metasurface-based patch antenna loaded with a carbon nanotube (CNT) thin layer for detection of deoxyribonucleic acid (DNA). The measured results demonstrate a frequency shift of about 69 MHz and a phase shift of about 28° for Al loaded with both CNTs and DNA in comparison with the same antenna loaded just with CNTs. In the case of A2, the frequency shift and the phase shift of the antenna loaded with CNTs and DNA become equal to 704 MHz and 121°, respectively.