Reflection and transmission of ultra-wideband pulses for detection of vascular pressure variation and spatial resolution within soft tissues

Abstract

Ultra-wideband signals have a variety of applications. An upcoming medical application is the detection of the heart rate of patients. However, current UWB systems provide poor resolution and are only able to detect vessels with a large diameter, e.g. the aorta. The detection and quantification of vascular dilation of thinner vessels is essential to develop wearable ultra-wideband based devices for real-time detection of cardiovascular conditions of the extremities. The reflection and transmission processes of those signals within inhomogeneous bodies are complex and their prediction is challenging. In this paper, we present an experimental setup (UWB system; phantom) for the detection of vascular dilation within soft tissues. Furthermore, we suggest a theoretical simulation model for the prediction of the reflection of ultra-wideband pulses and compare these simulated predictions to results of measurements within the phantom. The results verify that we are able to identify vascular dilation within the simulation model and the experimental setup, depending on the depth of the vessel (20 mm, 40 mm, 60 mm).

Innovations in Ultra-Wideband Technologies

“…In 2016, Mackenberg et al [25] attempted to establish a UWB system that detects the vascular pressure based on the detection of vascular dilation inside an inhomogeneous tissue. The researchers found a correlation relationship between the major peaks of signal in time domain and the amplitude of supposed values.…”

“…These curves appear in a certain shape according to their values. Mathematically, these sinusoids are the result of the number of beats or cycles per second (frequency), the power of each frequency component (amplitudes), and the delay or advantage of a signal (phase), which describe the angular displacement of two sinusoidal functions [23,25]. The key to transmitting the information is through the use of waves with more complex shapes, as a result of a combination of different sinusoids [25].…”

“…Mathematically, these sinusoids are the result of the number of beats or cycles per second (frequency), the power of each frequency component (amplitudes), and the delay or advantage of a signal (phase), which describe the angular displacement of two sinusoidal functions [23,25]. The key to transmitting the information is through the use of waves with more complex shapes, as a result of a combination of different sinusoids [25]. Depending on the frequency of these waves, indoor positioning wireless technologies are classified into different types (see introduction section).…”

“…Several investigations were reported earlier to create band notch function at WLAN band for ultra-wideband systems in [19][20][21][22][23][24][25][26][27][28][29][30]. Methods include inserting λ/4 and λ/2 slot resonators on the ground plane [19], using a pair of ground stubs locating along the edge of the ground plane [20], inserting open stub in the printed folded monopole [21], etching folded U-shaped slots in the feed line of the antenna [22,23], incorporating SRR slots on radiating element [24], quarter-wave stub connected to the ground [25], adding protruding two rectangular stubs on the ground plane [26], with a slot of length 1.0 λ in the radiator [27], open-ended quarter-wavelength L-shaped slots were etched on the rectangular radiating patches [28], using C-shaped and Z-shaped slot resonators on the ground [29], employing elliptical SRR on the radiating element [30].…”