Dielectric waveguide ring resonator-based biosensor for dielectric fluid spectroscopy in the THz domain

This paper presents the design of a broadband biosensor based on a high-resistive silicon (HR-Si) dielectric waveguide ring resonator (DWGR²). Sub-THz to THz sensing technologies have become increasingly popular in biosensing, medical, as well as food processing applications. Therefore, non-invasive dielectric measurements of fluids offer a wide range of information. The miniaturization of liquid volumes by microfluidics facilitates the sensing and metrology of dielectric fluids in nanoliter quantities, which is particularly advantageous for the analysis of valuable samples. Hence, the principal design as well as the crucial optimization steps for a broadband sensor design between 320 and 400 GHz are presented. This sensor features a unique sensing window that is decoupled from both the input and output of the device. Additionally, a fluid channel is incorporated to guide the liquid into the sensing region. The sensor will be able to characterize different fluids and their evaporation times, as well as the relative permittivity of fluids, which can be estimated over the whole frequency band. Furthermore, an automated tracking algorithm can be developed to extract all resonance information and derive a comprehensive dataset for analysis.