M. B. Chernyaeva

High-precision terahertz spectroscopy for noninvasive medicine diagnostics

Abstract In recent years methods for exhaled breath analysis have been developing all around the world. The exhaled breath analysis could result in a powerful tool for noninvasive medicine. The work presented in this paper is concerned with gas analyzers for exhaled breath diagnostics. The analyzers are based on high-precision spectrometers of the THz frequency range, which provide high resolution, high sensitivity and detect a wide range of detectable substances. The spectrometers work on non-stationary effects (phase-switching and fast sweep of frequency). The analyzers have been successfully applied for the detection of various biomarkers (nitric oxide, acetone, ammonia, methanol, ethanol) in the breath of conditionally healthy volunteers and patients with various cancerous and noncancerous diseases.

Using the methods and facilities of nonsteady-state spectroscopy of the subterahertz and terahertz frequency ranges for noninvasive medical diagnosis

This paper discusses ways to implement terahertz-range spectrometers based on the effects of freely damped polarization and rapid traverse of the frequency range. It presents the results of using developed spectrometers to record the presence of ammonia, acetone, and nitric oxide in exhaled air, as well as to analyze a liquid (Custodiol) for flushing transplanted parenchymatous organs.

Two-Frequency THz Spectroscopy for Analytical and Dynamical Research

Development of high-sensitivity and high resolution analytical spectroscopy is an area of active research interest currently. In the paper a method of two-frequency THz spectroscopy is presented. A laboratory model of spectrometer using two independent radiation sources of 118-178 GHz and 330-390 GHz ranges and a single detector with 500-2500 V/W sensitivity is presented. Test measurements allowed detecting two gases simultaneously with the minimal registration period of 4 μs and the hardware resolution of 1 kHz. These experiments proved this new trend in analytical spectroscopy to have wide application prospects for a variety of fundamental and applied scientific problems. In the first place, it is laboratory modeling of the processes of atmospheric and space chemistry, studying of their dynamics as well as transformations and changes of mixture composition. Besides, the proposed method can be applied to investigations of fast processes, detection of intermediate and short-lived products of chemical reactions.

Terahertz spectroscopy of heavy and superheavy water vapors

The paper reports on preliminary results of a study into a possibility of developing a fast method of atmospheric air analysis for the purpose of determination of the isotope composition of water vapors (H<inf>2</inf>¹⁸O, HD¹⁶O, HTO) with the method of non-stationary terahertz (THz) range spectroscopy.

Using the methods of multi-frequency spectroscopy for sensing

Nowadays the development of analytical spectroscopy with high performance, sensitivity and spectral resolution is attended. In the paper the method of two-frequency THz spectroscopy as well as the laboratory model of the spectrometer with using two independent radiation sources and a single detector of THz radiation are presented. The preliminary measurements have testified this new direction of analytical spectroscopy to open widespread trends of its using for various basic and applied problems of physics, chemistry, astronomy, medicine and biology. First of all, there are laboratory modeling the processes of atmospheric and space chemistry, studying of their dynamics as well as transformations and changes of mixture composition. Besides, the method presented can be applied for investigations of fast processes, detecting the intermediate and short time living products of chemical reactions.

Multifrequency high precise subTHz-THz-IR spectroscopy for exhaled breath research

Nowadays the development of analytical spectroscopy with high performance, sensitivity and spectral resolution for exhaled breath research is attended. The method of two-frequency high precise THz spectroscopy and the method of high precise subTHz-THz-IR spectroscopy are presented. Development of a subTHz-THz-IR gas analyzer increases the number of gases that can be identified and the reliability of the detection by confirming the signature in both THz and MIR ranges. The testing measurements have testified this new direction of analytical spectroscopy to open widespread trends of its using for various problems of medicine and biology. First of all, there are laboratory investigations of the processes in exhaled breath and studying of their dynamics. Besides, the methods presented can be applied for detecting intermediate and short time living products of reactions in exhaled breath. The spectrometers have been employed for investigations of acetone, methanol and ethanol in the breath samples of healthy volunteers and diabetes patients. The results have demonstrated an increased concentration of acetone in breath of diabetes patients. The dynamic of changing the acetone concentration before and after taking the medicines is discovered. The potential markers of pre-cancer states and oncological diseases of gastrointestinal tract organs have been detected. The changes in the NO concentration in exhaled breath of cancer patients during radiotherapy as well as increase of the NH3 concentration at gastrointestinal diseases have been revealed. The preliminary investigations of biomarkers in three frequency ranges have demonstrated the advantages of the multifrequency high precise spectroscopy for noninvasive medical diagnostics.