Application of Terahertz Time-Domain Spectroscopy to Study the Microheterogeneities of Solutions: A Case Study of Aqueous Sugar Solutions

Penkov, Nikita V. "Application of terahertz time-domain spectroscopy to study the microheterogeneities of solutions: a case study of aqueous sugar solutions." In Photonics, vol. 10, no. 8, p. 887. MDPI, 2023.#

Abstract

The phenomenon of the formation of microheterogeneities (MHs) in solutions, which, according to chemical handbooks, are considered true solutions, has been known for a long time. MHs have been found in more than 100 binary solutions, many of which are used both in various scientific studies and in life. However, the nature of this phenomenon is largely unclear. It is only well-known that MHs are stable areas of increased concentration of one of the components of the solution. The main reason for the poor knowledge of MHs is the use of very few experimental methods, mainly light scattering methods. In this paper, the terahertz time-domain spectroscopy method was used for the first time to study MHs using the example of aqueous solutions of three sugars: glucose, fructose, and sucrose. This method gives the spectra of complex permittivity in the terahertz range, which are very informative when studying the hydrate shells of molecules in solutions. The idea of this study was that structuring sugar molecules with the formation of MHs changes their hydration. The characteristics of sugar hydration in solutions before and after filtration through a 20 nm filter, leading to the destruction of MHs, were compared. It has been shown that the water binding in the MHs of all three solutions is increased compared with the hydrate shells of individual sugar molecules. Also, for MHs’ fructose solution, a decrease in the number of hydrogen bonds between water molecules and an increase in the number of free water molecules was shown, which is not observed in MH glucose and sucrose solutions. This is explained by mutarotations of fructose molecules, leading to permanent significant rearrangements of the water structure in MHs. Thus, terahertz time-domain spectroscopy provides fundamentally new information about the MHs of aqueous solutions at the level of their hydration characteristics. The presence of MHs in solutions is a significant factor that has never been taken into account when studying the hydrate shells of various molecules in solutions using THz spectroscopy.

see https://www.mdpi.com/2304-6732/10/8/887

Application of Terahertz Pulses to Non-Destructive Testing

 Zarrinkhat, Faezeh, Philip F. Taday and Donald D. Arnone. "Application of terahertz pulses to non-destructive testing." Journal of Non Destructive Testing and Evaluation (JNDE) 20, no. 2 (2023): 35-43.

Abstract
For the past twenty years, TeraView has been a world leader in the application of terahertz pulses to solve problems for industry .Terahertz technology provides the opportunity of remote, safe, fast and accurate sensing. In recent years, there has been a growing interest from industry in applying terahertz pulses to process control .In this paper, there is a brief review of the generation and detection of terahertz waves (0.1 THz to 6THz) using photoconductive antennas. The applications of time-domain spectroscopy to gas, liquid and solids are discussed. Then, a number of industrial applications of terahertz pulsed imaging such as solar cells, pharmaceutical, battery production and automotive industries are highlighted.

see https://jnde.isnt.in/index.php/JNDE/article/view/51

Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic

 Fauquet, Frédéric, Francesca Galluzzi, Philip F. Taday, Rémy Chapoulie, Aurélie Mounier, A. Ben Amara, and Patrick Mounaix. "Terahertz time-domain spectro-imaging and hyperspectral imagery to investigate a historical Longwy glazed ceramic." Scientific Reports 14, no. 1 (2024): 19248.

Abstract

In this paper, we present the potential of Terahertz Time-Domain Imaging (THz-TDI) as a tool to perform non-invasive 3D analysis of an ancient enamel plate manufactured by Longwy Company in France. The THz data collected in the reflection mode were processed using noise filtering procedures and an advanced imaging approach. The results validate the capability to identify glaze layers and the thickness of ceramic materials. To characterize the nature of the pigments, we also use with X-ray images, visible near-infrared hyperspectral imaging spectroscopy, and p-XRF (portable X-ray fluorescence) to qualitatively and quantitively identify the materials used. The obtained information enables a better understanding of the decoration chromogens nature and, thus, to determine the color palette of the artists who produced such decorative object. We also establish the efficiency of a focus, Z-tracker, which enables to perform THz imaging on non-flat samples and to attenuate artifacts obtained with a short focus lens. Then, 3D images are extracted and generated, providing a real vision. We also report the evaluation of the internal damage state through the detection of fractures.

see https://www.nature.com/articles/s41598-024-69697-6

Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles

Khat, F. Zarrin, A. Pentland, P. F. Taday, and D. D. Arnone. "Terahertz Assessment of the Battery Electrodes Save Production Costs of Electric Vehicles." Journal of Non Destructive Testing and Evaluation (JNDE) 21, no. 2 (2024): 33-40. 

Abstract

The electric vehicle market has experienced remarkable growth in recent years. A primary objective within this industry is to lower production costs. Notably, battery packs, which constitute up to 40% of the total production cost, allocate about 64% of this to the manufacturing of electrodes. It is vital to monitor key battery parameters such as thickness, loading, density, conductivity, and porosity to minimize waste during electrode production. Until recently, there was no technology capable of simultaneously tracking these parameters. However, terahertz technology has emerged as a powerful, non-destructive, and safe method for assessing battery electrodes.

Battery electrodes are coated on substrates made of materials like aluminium and copper. Since metals completely reflect terahertz waves, it's possible to measure the electrodes in reflection mode. This approach allows for the determination of the coating's thickness and its complex refractive index, which can be interpreted to deduce key electrode parameters.

In our study, we utilized TeraView's latest advancement, the TeraCota, a terahertz system designed for industrial applications, equipped with a self-referencing terahertz sensor. The sensor, mounted on a gantry, provided a terahertz image of the electrode loading and allowed for a direct comparison with an optical image, revealing defects on the cathode. We achieved an accuracy of 0.01 g/cm3 when comparing density measurements obtained through a terahertz sensor with those measured physically in the lab. Furthermore, the thickness measurements via the terahertz system agreed with those obtained using a micrometre to within less than 1 µm. Similarly, when comparing the conductivity measured by terahertz with DC conductivity measured via a four-point probe, the trends were consistent. Ongoing research into porosity has shown that the refractive index correlates with the porosity of specific electrode sets, indicating the potential for broader application. This comprehensive approach demonstrates the significant advantages of integrating terahertz technology into the battery electrode manufacturing process, potentially revolutionizing the industry by enhancing efficiency and reducing waste.

see https://jnde.isnt.in/index.php/JNDE/article/view/84

Exploring Porosity in Battery Electrodes: Terahertz Technology Unveiling Remote Sensing

 Zarrinkhat, Faezeh, Arturo I. Hernandez-Serrano, Alasdair Pentland, Philip F. Taday, Donald D. Arnone, and Michael Pepper. "Exploring porosity in battery electrodes: terahertz technology unveiling remote sensing." In 2024 49th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), pp. 1-2. IEEE, 2024.

Abstract:

Porosity significantly influences lithium-ion battery performance, impacting cell capacity, voltage, and specific power - critical to designers. Terahertz technology enables non-destructive, remote porosity assessment, addressing limitations in current measurement methods.

see https://ieeexplore.ieee.org/abstract/document/10697663