Submillimeter-Wave Permittivity Measurements of Bound Water in Collagen Hydrogels via Frequency Domain Spectroscopy

Tamminen, Aleksi; Baggio, Mariangela; Nefedova, Irina; Sun, Qiushuo; Anttila, J.; Ala‐Laurinaho, Juha; Brown, E. R.; Wallace, Vincent P.; Pickwell‐MacPherson, Emma; Maloney, Thaddeus; Salkola, Mika; Deng, Sophie X.; Taylor, Zachary D.

doi:10.1109/tthz.2021.3088273

Cited by 11 publications

(5 citation statements)

References 31 publications

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“…The comparison PO results at 275 GHz in Figure 13(d) show little apparent contrast variation for changing target location and are, qualitatively, insufficient for detecting misalignment. This is consistent with previous experimental [18,19]. and simulation [16] results in the WR-3.4 band.…”

Section: Displaced Target Imaging Resultssupporting

confidence: 93%

“…Furthermore, if the optimal positions are displaced from each other by more than ~1 mm (further discussed in later sections) the optimal MMW system position may correspond to ~ 0 signal (no discernable image) in the THz system due to walk-off losses and degradation in coupling efficiency. Experimentally, the optimal position of the MMW system relies on 3D scans over a very fine (~λ/6) grid and analysis of peak amplitude in the Fourier transformed, time domain traces at each grid point [18,19]. Thus, a good approach is to find the optimal MMW position and then independently tweak the THz system alignment.…”

Section: Bmentioning

confidence: 99%

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650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

Baggio

Dabironezare

et al. 2022

IEEE Trans. THz Sci. Technol.

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A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing 5 off-axis parabolic mirrors, a thin film beam splitter, and 2-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.

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Section: Displaced Target Imaging Resultssupporting

confidence: 93%

Section: Bmentioning

confidence: 99%

650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

Baggio

Dabironezare

et al. 2022

IEEE Trans. THz Sci. Technol.

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“…The material model comprises of free water (double Debye model [28]) and a second constituent of permittivity 2.9. As reported in [29], a two material model has been theorized based on the assumption that collagen and bound water are linked to each other and their interaction with submillimeter waves, described by permittivity, is similar. However, the authors acknowledge that the model can benefit from further study of this particular collagen hydrogel and potential, subsequent model modification with additional constituents and/or revised relaxation terms.…”

Section: Phantom Targets Experimental Resultsmentioning

confidence: 99%

Submillimeter-Wave Cornea Phantom Sensing Over an Extended Depth of Field With an Axicon-Generated Bessel Beam

Baggio

Tamminen

Lamberg

et al. 2023

IEEE Trans. THz Sci. Technol.

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The feasibility of a 220 -330 GHz zero order axicon generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25-degree cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate a monotonically decreasing, band integrated, backscatter intensity for increasing radius of curvature from 7 -11 mm, when lens reflector and optical axis are aligned. Further, for radii >= 9.5 mm, maximum signal was obtained with a 1 mm transverse displacement between lens and reflector optical axes arising from spatial correlation between main lobe and out of phase side lobes. Thickness and permittivity parameter estimation experiments were performed on an 8 mm radius of curvature, 1 mm thick fused quartz dome over a 10 mm axial span. Extracted thickness and permittivity varied by less than ~ 25 μm and 0.2 respectively after correction for superluminal velocity. Estimated water permittivity and thickness of water backed gelatin phantoms showed significantly more variation due to a time varying radius of curvature. To the best of our knowledge, this is the first work that describes axicon generated Bessel beam measurements of layered spheres with varying radii of curvature, in the submillimeter range.

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“…They verified the constant nonfreezing bound-water mass with a distinct property compared to pure water. 212 Arikawa et al used THz-TDS to measure disaccharide-water solutions. 213 The use of the ATR geometry circumvents the high attenuation problem of water in a transmission measurement; thus, a broad bandwidth of 0.5-2.6 THz can be investigated.…”

Section: Interaction With Watermentioning

confidence: 99%

Terahertz (THz) biophotonics technology: Instrumentation, techniques, and biomedical applications

Chen

Lindley-Hatcher

Stantchev

et al. 2022

Chemical Physics Reviews

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Terahertz (THz) technology has experienced rapid development in the past two decades. Growing numbers of interdisciplinary applications are emerging, including materials science, physics, communications, and security as well as biomedicine. THz biophotonics involves studies applying THz photonic technology in biomedicine, which has attracted attention due to the unique features of THz waves, such as the high sensitivity to water, resonance with biomolecules, favorable spatial resolution, capacity to probe the water–biomolecule interactions, and nonionizing photon energy. Despite the great potential, THz biophotonics is still at an early stage of development. There is a lack of standards for instrumentation, measurement protocols, and data analysis, which makes it difficult to make comparisons among all the work published. In this article, we give a comprehensive review of the key findings that have underpinned research into biomedical applications of THz technology. In particular, we will focus on the advances made in general THz instrumentation and specific THz-based instruments for biomedical applications. We will also discuss the theories describing the interaction between THz light and biomedical samples. We aim to provide an overview of both basic biomedical research as well as pre-clinical and clinical applications under investigation. The paper aims to provide a clear picture of the achievements, challenges, and future perspectives of THz biophotonics.

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Submillimeter-Wave Permittivity Measurements of Bound Water in Collagen Hydrogels via Frequency Domain Spectroscopy

Cited by 11 publications

References 31 publications

650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

650 GHz Imaging as Alignment Verification for Millimeter Wave Corneal Reflectometry

Submillimeter-Wave Cornea Phantom Sensing Over an Extended Depth of Field With an Axicon-Generated Bessel Beam

Terahertz (THz) biophotonics technology: Instrumentation, techniques, and biomedical applications

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