Electromagnetics in Medical Applications: The Cardiopulmonary Stethoscope Journey

3-D Printed UWB Microwave Bodyscope for Biomedical Measurements

“…As the gap height of the EGRH antenna when filled with a high permittivity material has feasible dimensions, it has been chosen 3D printing as the fabrication technique. The proposed EGRH antenna may be compared to the Microwave Sthetoscope [14], [15], a very compact design optimized for a close frequency band (0.7 to 1.5GHz) mainly intended for in-vivo reflectometry for vital signals, designed to have certain focusing capability inside the human body at the price of a non-planar geometry.…”

No-touch measurements of vital signs in small conscious animals

“…Respiration can often be the dominant signal and become a major interference to accurate heartbeat detection. RF methods based on the transmission line model (19)(20)(21) again require good impedance matching of the skin electrodes and hence the associated surface preparation. Small animals pose further challenges for most of these previous RF methods because of their limited signal sensitivity.…”

Microwave Near-Field Dynamical Tomography of Thorax at Pulmonary and Cardiovascular Activity

“…In this case, Equation (A22) is a convolution equation with respect to transversal coordinates, and it is possible to obtain the transversal spectrum of the scattered field in the form of a one-dimensional integral with respect to the depth coordinate z that includes the product of the transverse spectrum of inhomogeneity and the integral form of the corresponding transverse spectra of the Green functions: where the exact formulas for the Green functions were obtained in [ 19 ] for inhomogeneity in layered media. Substituting (A23) in (A2) gives a one-dimensional integral equation obtained in [ 19 ], which was also used in the multifrequency method in cases of frequency-independent permittivity [ 20 , 21 ]: From (A24) and (A1), one has the integral equation for the spectrum of the real-valued pulse: As is seen, Equation (A26) is, in general, an underdetermined equation that cannot be used directly in pulse diagnostics. However, in the case of the real-valued , (A24) is reduced to the integral equation: with the kernel Based on Equation (A24) with the kernel (A25), it is possible to propose various schemes of the tomography method based on data of the single-frequency measurements with the variable parameters of the source-receiver offset (base) similar to the method that was proposed and studied by the authors in [ 25 ].…”

“…Later, with the improvement of sensors, experimental studies at frequencies of 0.5–10 GHz were carried out [ 19 , 20 ], where phase variations of the signal related to breathing and heart activity were observed at the frequency of 0.92 GHz. Recently, measurements using advanced techniques and matched sensors have demonstrated the difference in heart-related signals between healthy people and people after a heart attack, as well as the sensitivity of scattered signals to the pulmonary edema [ 21 ].…”