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Biomedical subjects

S S Stuchly

Publications and source records attributed to S S Stuchly.

30 records · Page 2Linked to original sources
PubMed1983

Monitoring variations of biological impedances using microwave Doppler radar.

A microwave Doppler radar for continuously monitoring time-varying biological impedances is described. The radar compares the phase of the signal scattered from a region of biological tissue with that of the transmitted signal. The phase changes of the scattered signal are an indication of the net impedance changes within the test region due to various physiological processes, for example, the displacements of blood vessels during the cardiac cycle. A Doppler radar, equipped with a matched antenna, was tested with a simulation model and its detection characteristic was found to be a sinusoidal function of the antenna-object spacing. Tests with healthy human subjects were also performed at 3 GHz and 10.5 GHz. It was found that the 3 GHz Doppler radar has significantly greater penetration in tissues but is less sensitive to changes of the biological impedance than the 10.5 GHz system.

Doppler Effect↗
PubMed1982

Dielectric properties of animal tissues in vivo at radio and microwave frequencies: comparison between species.

An improved and modified technique with an open-ended coaxial-line sensor was used for measurement of the dielectric properties of animal tissues in vivo. The permittivity of skeletal muscle, brain cortex, spleen and liver of live cats and rats was measured at frequencies between 0.1 and 10 GHz. The results were compared with various published data on in vivo permittivity of the same and other species. The differences between the properties of the same tissue for various animals are very small. The tissues properties at frequencies above 1 GHz correlate well with the water content. Practically all water in the skeletal muscle is in the free form, while in other tissues both free and bound water are present.

Animals↗
PubMed1981

Dielectric properties of animal tissues in vivo at frequencies 10 MHz--1 GHz.

An open-ended coaxial line sensor in conjunction with an automatic network analyzer was used to measure in vivo the permittivity of several feline tissues (skeletal and smooth muscle, liver, kidney, spleen, and brain--gray and white matter) at frequencies between 10 MHz and 1 GHz. The estimated uncertainties of measurement were between 1.5% and 5%. The data are in general agreement with previously obtained data in vitro and in vivo. Significant differences in the properties of different types of the same tissue (eg, skeletal and smooth muscle) were observed. Many tissues were found to be non-homogeneous in its permittivity.

Animals↗
PubMed1980

Open-ended rectangular waveguides as antennas for medical diagnostics.

Open-ended rectangular waveguides, potentially useful as microwave antennas for medical diagnostics are described. Reflection coefficients have been measured for the waveguides fitted with standard flanges in contact with water and skin. Antenna matching to the tissue is discussed. Near-field radiation patterns in phantom solutions were measured to obtain operature and depth distribution patterns.

Humans↗