Development of a hybrid method for noninvasive determination of blood pressure with UWB radar (ultra wideband) and ultrasound
|Duration:||01.06.2018 - 31.05.2020|
|Project Leader:||Prof. Dr.-Ing Horst Hellbrück|
|Staff:||Roman Kreiger, B.Sc., Dipl.-Ing. (FH) Gunther Ardelt|
Since the release of UWB technology by the Federal Communications Commission in 2002, a number of medical applications have emerged. Ultrasound is already used in medicine and has become established in almost all medical fields, including vascular diagnostics.
The medical applications of UWB systems are divided into the areas of vital signs detection and imaging. Reflection-based radar systems are used, which detect the interfacial reflections of individual tissue transitions. For example, it is possible to detect the diameter change of the aorta whose heartbeat-based diameter change is on the order of a few hundred micrometers.
Experimental ultrasound studies prove that it is possible to determine the blood pressure in arteries under defined conditions. Ultrasound is used to measure the thickness and extent of the vessel walls as well as the flow velocity profiles in the blood.
Both methods have the potential to measure blood pressure. UWB is more likely to be classified as a dynamic exercise under stress and exercise, while ultrasound provides benefits in a quiet location and low blood pressure. The parallel application can provide significant synergistic effects in the developmental phase and application.
The main objective of the research project ANIPULS is to develop a method for the continuous, non-invasive detection of arterial blood pressure based on a combined transmission and reflection approach with electromagnetic ultrabroadband signals. In particular, it will be investigated how far beyond the currently available methods the measurement accuracy can be increased by the novel approach. The combination as a hybrid method with ultrasound is used for referencing and improving the measurement in hypotonic circulatory situations. Central goals are the design of a suitable measurement method as well as the construction of a model for the evaluation of the measurement results. This approach, supported by simulation results generated in parallel, aims to measure the pressure conditions in the vessel throughout the clinically relevant area. In this case, the pressure is recorded continuously with a reference system in the constructed model and within the vessel section to be examined. The flow measurement in the system and the analysis of changes in the vascular wall by ultrasound provide additional parameters for integration in the final validation of the structure, taking into account a standardized, statistically reliable method. Another goal is the testing of the system in healthy volunteers, with a corresponding data of the model studies.
Due to the requirement to be able to measure the arterial blood pressure non-invasively and continuously precisely, as well as due to the still insufficient accuracy of existing procedures, here an approach is pursued, which combines previous transmission and reflection approaches of the UWB technique and combined with ultrasound. In this case, ultrasound serves as a reference to the UWB-determined vessel wall extent, and at low blood pressure as additional information to increase the measurement accuracy.
|||Brachialis Pulse Wave Measurements with Ultra-Wide Band and Continuous Wave Radar, Photoplethysmography and Ultrasonic Doppler Sensors , In Sensors Multidisciplinary Digital Publishing Institute (MDPI), volume 21, 2021. [bib] [abstract]|
The measurement and analysis of the arterial pulse wave provides information about the state of vascular health. When measuring blood pressure according to Riva-Rocci, the systolic and diastolic blood pressure is measured non-invasively with an inflatable pressure cuff on the upper arm. Today’s blood pressure monitors analyze the pulse wave in reference to the rising or falling cuff pressure. With the help of additional pulse wave analysis, one can determine the pulse rate and the heart rate variability. In this paper, we investigated the concept, the construction, and the limitations of ultrawideband (UWB) radar and continuous wave (CW) radar, which provide continuous and non-invasive pulse wave measurements. We integrated the sensors into a complete measurement system. We measured the pulse wave of the cuff pressure, the radar sensor (both UWB and CW), the optical sensor, and ultrasonic Doppler as a reference. We discussed the results and the sensor characteristics. The main conclusion was that the resolution of the pulse radar was too low, even with a maximum bandwidth of 10 GHz, to measure pulse waves reliably. The continuous wave radar provides promising results for a phantom if adjusted properly with phase shifts and frequency. In the future, we intend to develop a CW radar solution with frequency adaption.
|||Towards Intrinsic Molecular Communication Using Isotopic Isomerism , In Open Journal of Internet Of Things (OJIOT) RonPub, volume 4, 2018. [bib] [pdf] [abstract]|
In this paper we introduce a new approach for molecular communication (MC). The proposed method uses isotopomers as symbols in a communication scenario, and we name this approach isotopic molecular communication (IMC). We propose a modulation scheme based on isotopic isomerism, where symbols are encoded via isotopes in molecules. This can be advantageous in applications where the communication has to be independent from chemical molecular concentration. Application scenarios include nano communications with isotopes in a macroscopic environment, i.e. encoding freshwater flow of rivers or drinking water utilities, or medical applications where blood carries isotopomers used for communication in a human or animal body. We simulate the capacity of communication in the sense of symbols per second and maximum symbol rate for different applications. We provide estimations for the symbol rate per distance and we demonstrate the feasibility to identify isotopes reliably. In summary, this isotopic molecular communication is a new paradigm for data transfer independent from molecular concentrations and chemical reactions, and can provide higher throughput than ordinary molecular communications.
|||Reflection and transmission of ultra-wideband pulses for detection of vascular pressure variation and spatial resolution within soft tissues , In Biomedical Physics & Engineering Express, volume 2, 2016. [bib] [pdf] [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).