TERAHERTZ METASURFACES OPTIMIZED FOR BIOMOLECULAR DETECTION
Guillermo Naranjo, Xomalin Peralta
The University of Texas at San Antonio, San Antonio, TX.
In the last decade, the use of metasurfaces for detecting biological analytes in solutions at terahertz (THz) frequencies has increased. The most common design consists of split-ring resonators (SRR) with square tips. However, the absorbance of water at THz frequencies reduces the ability to measure the analytes in solution. The goal of this project is to optimize the metasurface design for biomolecular detection by modifying the SRR to include a second gap as well as the geometry of the tips defining the gap. Using a commercial-grade simulator based on the finite-difference time-domain method, we obtained the THz transmission spectra of double gap split ring resonator (dSRR) designs with and without a biomolecule present within the gap. We used realistic parameters for the metallization, substrate, and biomolecular layer and 4 different tip designs: square, sawtooth, round, and triangle. We calculated the differential transmission spectra and found that the sawtooth tips with a biomolecule present caused a reduction in the response of 40.4% relative to that of the square tips. In contrast, the rounded tips increased the response 1.7-times relative to that of the square tips, while the triangular tips lie somewhere in between. The results of these simulations seem to indicate that rounded tips provide the largest increase in sensitivity. To confirm these results, we will fabricate, measure, and compare the THz response of dSRR with 4 different tip geometries with a biomolecular overlayer.