Biosensing at the Nanoscale: Gold Fractal Nanoantennas for Non-Invasive Plasmonic Resonance Frequency Analysis

The biotechnology sector is focusing on developing biosensors that allow us to detect and monitor substances in vivo using non-invasive methods. For example, in substances detection using the label-less method, radiation in the mid-infrared (mid-IR) has been used to obtain the vibrational fingerprint. In this work, we propose to use plasmonic nanoantennas called spaceship to develop a SEIRA substrate that can be used in disease detection. The spaceship nanoantennas were fabricated using electron beam lithography. A potential SEIRA device was fabricated with Au spaceship nanoantennas based on gold fractal nanoantennas with dimensions of 5.5 µm long and 5 µm high, inner structure with 970 nm, 950 nm in length and height respectively. Arm width of 400 nm and 50 nm of thickness. The resonance frequency (νres) was analyzed using gold nanoantennas absorbance as a function of frequency where one peak was found at 33THz. Additionally, these results were corroborated with a simulation where the magnitude of the electric field E=7.79 V/m at 34.98 THz was found. These results allow us to propose spaceship nanoantennas as good candidates for the design of a SEIRA substrate.