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Electron Properties Investigation of the Near-Surface Region in Crystalline Semiconductors Using the Transverse Acoustoelectric Effect

Pustelny Tadeusz

Archives of Acoustics

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2022

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Vol. 47, No. 4

565--579

EN

The paper presents the acoustoelectric phenomenon in a layered structure: piezoelectric waveguide – semiconductor. The publication presents an original acoustic method for determining the electrical and electron parameters of the subsurface area in crystalline semiconductors. The method is based on the so-called transverse acoustoelectric effect realized in a layer system: piezoelectric waveguide with Rayleigh surface acoustic wave – semiconductor. The paper discusses the physical foundations of the transverse acoustoelectric effect in the piezoelectric – semiconductor layer system, taking into account the distinctness of the physical properties of the semiconductor near-surface region in relation to its volumetric properties. The work covers many experimental studies of the near-surface region of semiconductors. The original method was presented to determine such surface parameters as: surface potential, surface conductivity, mobility of carriers in the subsurface area, life time of charge carriers in surface states. By means of the acoustic method the following semiconductors have been extensively tested: indium phosphide InP and gallium phosphide GaP. These semiconductors are one of the main semiconductors of group III-V, which are the basis of modern photonics, optoelectronics as well as integrated optics. The work also includes an analysis of the measurement possibilities of the developed acoustic method and its limitations, as well as an analysis of the accuracy of the obtained values of the parameters of the subsurface area of crystalline semiconductors.

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Optical diagnostic system for visualization subcutaneous blood vessels

Opilski Zbigniew, Pustelny Tadeusz, Pach M., Hejczyk T.

Opto-Electronics Review

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2020

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Vol. 28, No. 2

64--68

EN

The paper presents a research concerning the issue of visualization of blood vessels in the human body. In the initial phase of the investigations the focus was on understanding the optical properties of human body tissues. Optical transmittance of human skin was measured. Skin transmittance reaches the maximum at around 670–850 nm and 970–1100 nm. The optimal wavelength suitable for work in reflected and transmitted light was chosen. It was based on extracting blood vessels from the image for using them further in a developed system. A unique measuring system with an integrated illuminator and highly sensitive light detectors for medical imaging and stereoscopic observation was created. The high usable value of the developed system was largely gained by the original numerical program for development of measurement results. The elaborated system of blood vessels’ visualization is a mobile device. It was tested for imaging subcutaneous blood vessels. Three-dimensional observation of circulation and microcirculation in subcutaneous breast tissues is possible. Practical tests of the elaborated device for blood vessels’ medical stereoscopic observations were presented. Tests at a wavelength of 850 nm were performed. It is planned to conduct patient tests in the future at the Maria Skłodowska-Curie Institute - Oncology Center (MSCI), the Branch in Gliwice, Poland.

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Analysis of the Saw System with the PANI + Nafion Sensing Structure for Detection of Low Concentration Carbon Monoxide

Hejczyk Tomasz, Pustelny Tadeusz

Archives of Acoustics

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2020

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Vol. 45, No. 4

681--686

EN

The paper presents a measuring system based on two resonators with a SAW acoustic surface wave. One of the resonators contains a sensor structure consisting of a Nafion layer with a PANI polyaniline nanolayer deposited on it. The sensor structure was tested for carbon monoxide, with a very low concentration (5, 10, 15, 20 ppm) in the atmosphere of synthetic air. The structure sensitivity was tested for two different PANI thicknesses: (100 and 180 nm). The tests were carried out for two different temperatures: 308 K and 315 K. The investigations shows that the measuring system used with the acoustic surface wave together with the proposed sensing layers is sensitive to the presence of low concentration carbon monoxide molecules in the atmosphere of synthetic air.