Integrated On-Chip THz Sensors for Fluidic Systems Fabricated Using Flexible Polyimide Films

Abstract

AbstractÑWe investigate the use of an on-chip terahertz (THz) frequency sensor formed on a flexible, thin-film polyimide substrate to measure the properties of liquids encapsulated in a glass-walled capillary. We observe changes in the attenuation and velocity of the time-domain THz signal, which allows extraction of the broadband THz refractive index and relative attenuation coefficients of the liquid. The technique is used for sensing members of a homologous series of primary alcohols, and the results compared with those obtained from a free-space THz-TDS system.

Determination of Permittivity of Dielectric Analytes in the Terahertz Frequency Range Using Split Ring Resonator Elements Integrated with On-Chip Waveguide

“…In order to obtain the transmission spectra (S 21 ) of the waveguide with five integrated SRRs, two-port S-parameter simulations were performed. The THz signals were generated from wave-ports directly coupled to the PGL, as previously demonstrated in experiments [ 9 , 25 ]. We note that, using this method, the PGL mode is formed without a coplanar waveguide to PGL transition [ 26 ].…”

Terahertz surface plasmonic waves: a review

“…108 With respect to compactness, the integrated method is more applicable to excite THz SPWs on PGLs. 54,100,109 Based on the above-mentioned waveguide method for PGLs, Dazhang et al 100 integrated a photoconductive antenna in the region of parallel CPWs, on top of which a small patch of low-temperature GaAs was deposited, as shown in Fig. 2(f).…”

“…The same group also demonstrated that THz SPWs on a PGL could be excited by removing the ground planes at the two sides of the central structure connected to the PGL, which could help increase the frequency resolution. 54,109…”

“…Integrating a detection part within the propagation path is quite suitable for the highly confined THz SPWs on waveguide structures, such as textured structure chains or PGLs, where the fields are very strong and also fully carry the interaction information with other materials around the propagation path. 54,100,109,110 For instance, photoconductive antennas have been integrated onto PGLs for the detection of THz SPWs [see Fig. 2(f)].…”

“…Han et al 167 applied a periodic hole array to determine the film thickness by observing the frequency shift of the transmission dip contributed from the excitation of SPWs by the surface lattice. In particular, by fabricating the PGL on a flexible thin film and wrapping it around a thin-walled capillary, Russell et al 109 demonstrated that THz SPWs could sense the encapsulated liquid. When the THz SPWs propagate to the capillary, the dielectric environments with which the SPWs have interacted are determined by the type of the liquid.…”