Abstract
We developed hybrid slot antenna structures for microbial sensing in the THz frequency range, where silver nanowires (AgNWs) were employed to increase the sensitivity. In order to fabricate the hybrid devices, we partially etched the AgNW in the slot antenna region, where we can expect the field enhancement effect at the AgNW tip. We measured the resonant-frequency shift observed upon the deposition of a polymer layer, and observed that the sensitivity increased upon the introduction of AgNWs, with an enhancement factor of more than four times (approximately six times in terms of figure-of-merit). The sensitivity increased with the AgNW density until saturation. In addition, we tested devices with PRD1 viruses, and obtained an enhancement factor of 3.4 for a slot antenna width of 3 μm. Furthermore, we performed finite-difference time-domain simulations, which confirmed the experimental results. The sensitivity enhancement factor decreased with the decrease of the slot width, consistent with the experimental findings. Two-dimensional mapping of the electric field confirmed the strong field localization and enhancement at the AgNW tips.
Highlights
Terahertz (THz) spectroscopy is an efficient technique for non-contact, non-destructive, and label-free investigations of biological and chemical substances[1,2,3,4,5,6]
We developed hybrid slot antenna structures for microbial sensing in the THz frequency range, where the sensitivity was increased with the introduction of the AgNWs
We measured the resonant-frequency shift with the deposition of a polymer layer, and observed that the sensitivity increased for the device with AgNWs, with an enhancement factor of more than 3.8 (~6.7 in terms of FOM) for the slot antenna width of 15 μm
Summary
Terahertz (THz) spectroscopy is an efficient technique for non-contact, non-destructive, and label-free investigations of biological and chemical substances[1,2,3,4,5,6]. Nanogaps were incorporated in the metamaterials using the nanolithography method for an enhanced detection of viruses with a typical size smaller than 100 nm[15]. It is expensive and time-consuming to fabricate such nanoscale structures using conventional lithographic methods; advanced techniques are required to achieve the localized fields. We demonstrated that AgNW network films can be employed in plasmonic devices in the THz frequency range[23]; biological sensing applications with an enhanced sensitivity were not addressed. We fabricated THz hybrid slot antenna devices with individual AgNWs protruding in the slot area, for a highly sensitive detection of polymer films and microorganisms such as viruses. The experimental results were confirmed by finite-difference time-domain (FDTD) simulations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
