Lukas Peter

Pulse wave velocity measurement; developing process of new measuring device

Pulse wave velocity measurement (PWV) is non-invasive method to assess arterial stiffness. It is useful as a prevention of cardiovascular system diseases. This paper describes development and function of other possibility how to measure PWV. Device which is used for this study consists of dual channel hardware for photopletysmograph signal preprocessing, USB workstation for continuous conversion of measured data and data analyzing by LabView software. Output of the software is graphical user interface which displays measured signals and calculated values of pulse wave velocity.

Multiregional Segmentation Modeling in Medical Ultrasonography: Extraction, Modeling and Quantification of Skin Layers and Hypertrophic Scars

In the clinical practice of the burns treatment, an autonomous modeling of the burns morphological structure is important for a correct diagnosis. Unfortunately, the geometrical parameters of burns and skin layers are subjectively estimated. This approach leads to the inaccurate assessment depending on the experience of an individual physician. In our research, we propose the analysis of multiregional segmentation method which is able to differentiate individual skin layers in the ultrasound image records. The segmentation method is represented by the mathematical model of skin layers while other structures are suppressed. Skin layers are consequently approximated by their skeleton with target of the layers distance measurement. The main applicable output of our research is the clinical SW SkinessMeter 1.0.0 serving for an autonomous modeling and quantification of the skin layers.

Classification of Myopotentials of Hand’s Motions to Control Applications

Realization of the system for classification of hand’s gestures is described in this paper. The first goal was to create hardware that would be able to measure signal of myopotentials for computer analysis without external noise and with right amplification. The second goal was to program an algorithm which could classify specific gestures of hand. Hardware prototype of four measuring channels was created by combination of 2nd order filters and right amount amplification. The user is isolated from the power source using galvanic isolation because of usage of active electrodes. For digitizing the data, the Arduino Nano microcontroller was selected and programmed using defined communication protocol. The computer software is programmed in C# programming language. Signal processing and drawing to user interface is in real time. The one of five possible gestures that user made is chosen using fuzzy logic and designed system of scaling.

Investigation of a Possibility of ECG and PPG Common Measurement

Electrocardiography and Photoplethysmography are basic investigative methods used in healthcare. As the ECG and the PPG are non-invasive methods. The principle consists in ECG recording of electrical activity of the heart and the result of this sensing is a graph plotting—electrocardiogram. PPG is one of the main methods of measurement plethysmography when the result is a graphic record of pulse wave. The main function of PPG is the volumetric flow measurement of blood (e.g. in atherosclerosis, which is possible by vascular permeability derive their rigidity). Both of these methods are used for monitoring of cardiovascular system. It would be advantageous to have possibility to measure ECG and PPG from one place on human body. It would be also advantageous to have only one device and reduce number or size of sensors or electrodes. In this paper we describe developing such system and also investigation the ideal place for placing of sensors for satisfactory measurement.

Proposal of Physical Model of Cardiovascular System; Improvement of Mock Circulatory Loop

Each heart ejection gives the blood a pressure force and it creates a pulse wave which travels from the heart to peripheral blood vessels (blood vessel in fingers, toes, …). This pulse wave travels during arterial tree and it depends on arterial properties as elasticity, stiffness or thickness of the artery wall. It will be very useful to describe the relationship between blood pressure, pulse wave propagation and hemodynamics parameters in real or very similar conditions as are in real cardiovascular system. The whole cardiovascular system can be described as an electrical circuit with resistors (resistivity of blood vessels R), capacitors (compliance of blood vessels C) and inductors (inertance of blood vessels L). It is possible to evaluate all of parameters of arteries and developed physical model of cardiovascular system. Physical model has to simulate real conditions which are in human cardiovascular system. It would bring a better knowledge about the behaviour of cardiovascular system and improve its treatment. In this paper are describe possibilities how to model cardiovascular system and developing of physical model of cardiovascular system.

Thermal Energy Harvesting on the Bodily Surfaces of Arms and Legs through a Wearable Thermo-Electric Generator

This work analyzes the results of measurements on thermal energy harvesting through a wearable Thermo-electric Generator (TEG) placed on the arms and legs. Four large skin areas were chosen as locations for the placement of the TEGs. In order to place the generator on the body, a special manufactured band guaranteed the proper contact between the skin and TEG. Preliminary measurements were performed to find out the value of the resistor load which maximizes the power output. Then, an experimental investigation was conducted for the measurement of harvested energy while users were performing daily activities, such as sitting, walking, jogging, and riding a bike. The generated power values were in the range from 5 to 50 μW. Moreover, a preliminary hypothesis based on the obtained results indicates the possibility to use TEGs on leg for the recognition of locomotion activities. It is due to the rather high and different biomechanical work, produced by the gastrocnemius muscle, while the user is walking rather than jogging or riding a bike. This result reflects a difference between temperatures associated with the performance of different activities.

Defibrillator educational devices

Defibrillators are electronic sanitary apparatus, used for urgent surgery for restoration cardiac activity. Defibrillator is fast, effective and easy a method surgery and therefore are still more used. Practical education of engineers in this topic is limited, in particular to the potential risk of unwanted defibrillation pulse during operation of the device. Therefore, we designed and implemented own defibrillator having the characteristics of standard defibrillator with the difference that the output energy of the defibrillation pulse is lowered to a level that is safe for students. Although our proposed defibrillation pulse generator is responsible for its quality parameters of commercial devices is composed of standard electronic components, so that it could implement every student himself on solderless field.

Multiregional Fuzzy Thresholding Segmentation Completed by Spatial Median Aggregation: Modeling and Segmentation of Early Pathological Findings of Articular Cartilage

In the field of the clinical orthopedics, articular cartilage is one of the essential object which is evaluated. From the clinical point of view, the early osteoarthritis changes are increasingly challenging especially due to their insufficient contras against image background. Therefore, those findings are often only subjectively estimated from MR records. We have proposed a mathematical model based on the multiregional thresholding methodology, which is able to differentiate of physiological articular cartilage from osteoarthritic findings. Segmentation method is composed from two parts: brightness modeling via fuzzy triangular functions, and spatial median aggregation procedure taking into account the spatial pixel information which makes the model robust against noise and artifact which are often incorrectly classified. A method was tested on the sample of MR data from Proton Dense sequence and Fat Suppression sequence with satisfactory results.

The Use of Multichannel Photoplethysmography for the Analysis of Heart Rate Variability

Heart rate variability (HRV) is a parameter of heart reactivity which is used to describe fluctuation of intervals between two consecutive heart beats. The paper focuses on the analysis of HRV from PPG and ECG signals derived from multichannel PPG. The suitable methods of preprocessing of signals are described in order to obtain the accurate result of HRV analysis and several effects causing changes in HRV are evaluated. Its object is to evaluate accuracy of the measurement from PPG beside ECG because this method is not used in common practise and analyse the changes of HRV during day.

Comparison of methods for the evaluation of NIBP from pulse transit time

Non-invasive blood pressure measurement (NIBP) is one of the most discussed topic in cardiovascular medicine. Currently continuous measurement of blood pressure is possible by invasive methods, which makes the measurement impractical for Doctors and uncomfortable for the patients. It is possible to use special devices to measure blood pressure noninvasively continuously but there are still some problems with long time monitoring and comfort for patient. Physiologically there is connection between electrical and mechanical heart functions, propagation of pulse wave and blood pressure value. Our paper investigates various methods for the evaluation of NIPB from pulse transit time. We analyse real signals which we obtained during surgical interventions in Hospital, with invasive measurements of blood pressure waves, and non-invasive measurements of pulse waves and ECG signal.Non-invasive blood pressure measurement (NIBP) is one of the most discussed topic in cardiovascular medicine. Currently continuous measurement of blood pressure is possible by invasive methods, which makes the measurement impractical for Doctors and uncomfortable for the patients. It is possible to use special devices to measure blood pressure noninvasively continuously but there are still some problems with long time monitoring and comfort for patient. Physiologically there is connection between electrical and mechanical heart functions, propagation of pulse wave and blood pressure value. Our paper investigates various methods for the evaluation of NIPB from pulse transit time. We analyse real signals which we obtained during surgical interventions in Hospital, with invasive measurements of blood pressure waves, and non-invasive measurements of pulse waves and ECG signal.