THz ATR Spectroscopy for Inline Monitoring of Highly Absorbing Liquids

Soltani, Amin; Busch, Stefan; Plew, P.; Balzer, Jan C.; Koch, Martin

doi:10.1007/s10762-016-0285-6

Cited by 27 publications

(9 citation statements)

References 19 publications

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“…Typical sensing of polar liquids involve reflection or attenuated total reflection type measurement for determining small changes of the liquid's dielectric function due to high attenuation beyond the system dynamic range. [ 29–41 ] Our proposed design shows exceptionally large sensitivity of 129.3 GHz per refractive index unit (RIU) (simulation) and 124.3 GHz per RIU (experiment) for 28 µm thick microfluidic layers of different mixed ethanol–water solutions, which is higher than typical single torus toroidal designs reported earlier. [ 21–24 ] Thus, the dual‐torus toroidal metasensor with microfluidic channel offers a sensitive monitoring technology with enhanced sensitivity for liquid and biological sensing in real time.…”

Section: Introductionmentioning

confidence: 84%

Terahertz Microfluidic Sensing with Dual‐Torus Toroidal Metasurfaces

Liao

Gupta

et al. 2021

Advanced Optical Materials

104

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Toroidal excitation manifests as currents flowing on the surface of a torus along its meridians that are known as poloidal currents. Several intriguing phenomena such as nonradiating anapole excitation, dynamic Aharonov–Bohm effect, and vector potential in the absence of electromagnetic fields occur in the presence of toroidal excitations. Toroidal resonances in metamaterials also offer a platform to probe strong light–matter interactions in its proximity due to the nonradiating confinement of photons. Here, a dual‐torus toroidal flexible metasurface containing an array of overlapped split ring resonators is experimentally demonstrated, which results in strong field confinement for enhanced sensing of polar liquid analytes. Microfluidic integrated dual‐torus toroidal resonance experimentally shows significantly higher sensitivity of 124.3 GHz per refractive index unit compared to a single torus toroidal resonance. Flexible metasurfaces supporting dual torus toroidal resonance can find a wide range of applications in the development of ultrasensitive terahertz molecular sensors for probing real time monitoring of chemicals and biomolecules.

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Section: Introductionmentioning

confidence: 84%

Terahertz Microfluidic Sensing with Dual‐Torus Toroidal Metasurfaces

Liao

Gupta

et al. 2021

Advanced Optical Materials

104

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“…For soft materials and liquids, the attenuated total reflection (ATR) geometry is useful [117,118,119] because similar materials in contact with the prism surface have an ideally flat surface. The magnitude of the phase shift of the reflected signal is higher in A specific feature of the transmission mode is the need to accurately record the sample slice's thickness, since the thickness affects the absorption coefficient and refractive index.…”

Section: Thz Methods and Thz Technologymentioning

confidence: 99%

“…For soft materials and liquids, the attenuated total reflection (ATR) geometry is useful [117][118][119] because similar materials in contact with the prism surface have an ideally flat surface. The magnitude of the phase shift of the reflected signal is higher in the ATR mode than the reflection one.…”

Section: Thz Methods and Thz Technologymentioning

confidence: 99%

Diagnosis of Glioma Molecular Markers by Terahertz Technologies

et al. 2021

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This review considers glioma molecular markers in brain tissues and body fluids, shows the pathways of their formation, and describes traditional methods of analysis. The most important optical properties of glioma markers in the terahertz (THz) frequency range are also presented. New metamaterial-based technologies for molecular marker detection at THz frequencies are discussed. A variety of machine learning methods, which allow the marker detection sensitivity and differentiation of healthy and tumor tissues to be improved with the aid of THz tools, are considered. The actual results on the application of THz techniques in the intraoperative diagnosis of brain gliomas are shown. THz technologies’ potential in molecular marker detection and defining the boundaries of the glioma’s tissue is discussed.

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“…In recent decades, terahertz (THz) technology has attracted great interest in many application areas such as spectroscopic sensing, nondestructive testing [1], and high-speed wireless communications [2]. In particular, applications in sensing have gained popularity because THz radiation has many positive properties, including the short wavelength associated with high spatial resolution [3], spectral fingerprinting of specific molecules, and low photon energy [4].…”

Section: Introductionmentioning

confidence: 99%

Photonic Crystal Resonator in the Millimeter/Terahertz Range as a Thin Film Sensor for Future Biosensor Applications

Zhao

Vora

et al. 2022

J Infrared Milli Terahz Waves

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With recent developments, terahertz (THz) technology has attracted great interest in many different fields of research and application. In particular, biosensors that detect a thin film of captured pathogens are in high demand for rapid diagnosis. Based on the interaction between analytes under test and electromagnetic (EM) field, THz resonators are sensitive to changes in the permittivity of the analyte and have the potential to become sensitive thin-film sensors. However, conventional metamaterial methods have low Q factors, leading to small amplitude variations and ambiguous detection. Here, we present a photonic crystal (PhC)–based resonator with a high Q factor that is sensitive to a monolayer of beads in the µm size range. The PhC resonator made of high resistivity silicon (HRSi) shows a Q factor of 750, which is much higher compared to metamaterial-based methods. Its resonance shift is linearly related to the coverage of the micron-sized beads on its surface. Moreover, simulation results with a thin film model of a single layer of the beads showed agreement with the experimental results. Although the achieved sensitivity needs to be improved by enhancing the field concentration on the analyte, our results suggest that THz PhC resonators with high Q factor are promising for biosensing applications. We anticipate our work to be a starting point for biochips with improved sensing capabilities and more functionality.

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THz ATR Spectroscopy for Inline Monitoring of Highly Absorbing Liquids

Cited by 27 publications

References 19 publications

Terahertz Microfluidic Sensing with Dual‐Torus Toroidal Metasurfaces

Terahertz Microfluidic Sensing with Dual‐Torus Toroidal Metasurfaces

Diagnosis of Glioma Molecular Markers by Terahertz Technologies

Photonic Crystal Resonator in the Millimeter/Terahertz Range as a Thin Film Sensor for Future Biosensor Applications

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