Sub-terahertz silicon-based on-chip absorption spectroscopy using thin-film model for biological applications

Abstract

Spectroscopy in the sub-terahertz (sub-THz) range of frequencies has been utilized to study the picosecond dynamics and interaction of biomolecules. However, widely used free-space THz spectrometers are typically limited in their functionality due to low signal-to-noise ratio and complex setup. On-chip spectrometers can revolutionize THz spectroscopy allowing integration, compactness, and low-cost fabrication. In this paper, a low-loss silicon-based platform is proposed for on-chip sub-THz spectroscopy. Through functionalization of silicon chip and immobilization of bio-particles, we demonstrate the ability to characterize low-loss nano-scale biomolecules across the G-band (0.14–0.22 THz). We also introduce an electromagnetic thin-film model to account for the loading effect of the immobilized biomolecules, i.e. dehydrated streptavidin and immunoglobulin antibody, as two key molecules in the biosensing discipline. The proposed platform was fabricated using a single mask micro-fabrication process, and then measured by a vector network analyzer (VNA), which offers high dynamic range and high spectral resolution measurements. The proposed planar platform is general and paves the way towards low-loss, cost-effective and integrated sub-THz biosensors for the detection and characterization of biomolecules.

Improved In Situ Characterization of Electrochemical Interfaces Using Metasurface‐Driven Surface‐Enhanced IR Absorption Spectroscopy

“…In biomolecular sensing, a plethora of alternatives are used to improve molecular detection using controlled and tuneable EM near‐field enhancement via the excitation of resonances through tailored system parameters on the nanoscale. Examples are plasmonic nanoparticles, non‐plasmonic nanogap dimers, [ 13 ] metasurfaces based on plasmonics [ 14 ] or exotic phenomena like quasi‐bound states in the continuum, [ 15 ] waveguides [ 16 ] or 2D‐integrated [ 17 ] platforms, among others. [ 18 ] Plasmonic‐based sensors have become the method of choice in label‐free detection of biomolecules.…”

Enhancement of wide-band trace terahertz absorption spectroscopy based on microstructures: a review

“…Increasing the waveguide length, even up to a few centimeters, will lead to more effective interaction. 36 Metal waveguides have been used in terahertz spectroscopy for boosting the detection of absorption spectra of various organic molecular samples. J. S. Melinger et al used a metal parallel plate waveguide (PPWG) to enhance the detection of the absorption spectra of several organic molecular films, such as explosive trimethylene trinitramine (RDX) and molecule 4iodo-4 0 -nitrobiphenyl (4INBP), of about 150 mg in the terahertz frequency of 0.1-4.0 THz.…”

“…Increasing the waveguide length, even up to a few centimeters, will lead to more effective interaction. 36…”