Detection of Microplastic in Salts Using Terahertz Time-Domain Spectroscopy

Ultra-High Sensitivity Terahertz Microstructured Fiber Biosensor for Diabetes Mellitus and Coronary Heart Disease Marker Detection

Diabetes Mellitus (DM) and Coronary Heart Disease (CHD) are among top causes of patient health issues and fatalities in many countries. At present, terahertz biosensors have been widely used to detect chronic diseases because of their accurate detection, fast operation, flexible design and easy fabrication. In this paper, a Zeonex-based microstructured fiber (MSF) biosensor is proposed for detecting DM and CHD markers by adopting a terahertz time-domain spectroscopy system. A suspended hollow-core structure with a square core and a hexagonal cladding is used, which enhances the interaction of terahertz waves with targeted markers and reduces the loss. This work focuses on simulating the transmission performance of the proposed MSF sensor by using a finite element method and incorporating a perfectly matched layer as the absorption boundary. The simulation results show that this MSF biosensor exhibits an ultra-high relative sensitivity, especially up to 100.35% at 2.2THz, when detecting DM and CHD markers. Furthermore, for different concentrations of disease markers, the MSF exhibits significant differences in effective material loss, which can effectively improve clinical diagnostic accuracy and clearly distinguish the extent of the disease. This MSF biosensor is simple to fabricate by 3D printing and extrusion technologies, and is expected to provide a convenient and capable tool for rapid biomedical diagnosis.

Terahertz and Millimeter Wave Sensing and Applications

The field of terahertz and millimeter wave science and technology has evolved in recent years into an area attracting a lot of attention from all sides of science, industry, and the public [...].

Terahertz Time-Domain Spectroscopic Study of Tricalcium Silicate

In this study, the terahertz (THz) spectra of C₃S were obtained in the 0.4-2.3 THz frequency range using different sample preparation methods. In the spectra, a sharp absorption peak of C₃S was found at 2.03 THz. Under controlled conditions, the mass ratio of C₃S was the most critical factor affecting the strength of the absorption peak, and the absorption coefficient followed the Beer-Lambert law, exhibiting a linear relationship with the mass ratio of C₃S. The intrinsic dielectric constants of C₃S and polyethylene (PE) were calculated in accordance with the Maxwell-Garnett (MG), Bruggeman (BM), and Landau-Lifshitz-Loovenga (LLL) models, using two-phase composite samples. The results show that the LLL model had the highest accuracy.

Terahertz Spectroscopic Analysis of Lactose in Infant Formula: Implications for Detection and Quantification

Lactose plays a significant role in daily lives as a constituent of various food and pharmaceutical products. Yet, lactose intolerance conditions demand low-lactose and lactose-free products in the market. These increasing nutritional claims and labels on food products entail simple and reliable methods of analysis that can be used for meeting quality standards, nutritional claims and legal requirements. In this study, terahertz time–domain spectroscopy (THz-TDS) was employed to analyse α-lactose monohydrate qualitatively and quantitatively in food products. Both absorption spectra and absorption coefficient spectra were investigated for their prediction performance. Regression models for lactose quantification using peak area and height of the absorption peaks 0.53 and 1.37 THz were developed and assessed in infant formula samples. Satisfactory prediction results were achieved in ideal conditions with pure standards, but not in all predictions of infant formula samples. Reasons and further implications are discussed.

A microwave-based technique as a feasible method to detect plastic pollutants in experimental samples

Plastic-derived pollutants are hazardous and pervasive in the environment, and their detection is a challenge due to observational constraints of various dimensions. Physical, chemical, thermal, and spectroscopic methods are extensively used to identify microplastics in environmental systems, but fundamental challenges exist in the isolation and analysis of nanoplastics from environmental samples. The promising practices are often destructive, rendering the samples inutile for further investigations. In this paper, a technique based on the measurement of the dielectric properties of the samples, carried out using the rectangular cavity perturbation technique at the S-band of microwave frequency of 2-4 GHz is proposed. The ability of this method to identify some of the most abundant types of plastics found in the environment, polypropylene, low-density polyethylene, high-density polyethylene, and cross-linked polyethylene, is demonstrated. Electrical characteristics at microwave frequencies such as absorption factor, dielectric constant, and dielectric loss tangent are found useful in the identification of various polymers in the samples. Further, this method can be applied to identify other environmentally stable performance and engineering polymers, which are not often investigated in the environmental matrices for their hazardous effects. This non-destructive measurement method is quick and straightforward and can be further developed to identify a wide range of plastic materials present in various environmental compartments.

Mathematical Modeling of Layered Nanocomposite of Fractal Structure

A model of a layered hierarchically constructed composite is presented, the structure of which demonstrates the properties of similarity at different scales. For the proposed model of the composite, fractal analysis was carried out, including an assessment of the permissible range of scales, calculation of fractal capacity, Hausdorff and Minkovsky dimensions, calculation of the Hurst exponent. The maximum and minimum sizes at which fractal properties are observed are investigated, and a quantitative assessment of the complexity of the proposed model is carried out. A software package is developed that allows calculating the fractal characteristics of hierarchically constructed composite media. A qualitative analysis of the calculated fractal characteristics is carried out.