Juan Ramos

Automatic detection of ECG ventricular activity waves using continuous spline wavelet transform

In this study, we present detection algorithms of characteristic points of the QRS and T waves based on the continuous wavelet transform (CWT) with splines. This technique can handle any integer scale and the analysis is not restricted to scales that are powers of two, which allows to use a wide range of scales and to more efficiently reduce noise and artifacts. Evaluation of the QRS detection algorithm performance has been done in eight ECG data files of the MIT-BIH database, and the accuracy has been of 99.5%. Evaluation of the detection algorithms of the QRS wave onset and offsets of QRS and T waves has been done in the CSE multi-lead measurement database, and the measurements were within the tolerance limits for deviations with respect of the manual measurements determined by the CSE experts. Therefore, the proposed algorithms to detect characteristic points of the QRS and T waves based on this technique allow the evaluation of the CWT in more scales, are robust to noise and artifacts and have the accuracy of a human expert.

Changes in myocardial electrical impedance in human heart graft rejection

Monitoring of post‐transplant heart rejection is currently based on endomyocardial biopsy analysis. This study aimed to assess the effects of heart graft rejection on myocardial electrical impedance.

A system for monitoring pill electrode motion in esophageal ECG

We present a system for monitoring the motion of the pill electrode in esophageal electrocardiography, which consists on measuring the electrical impedance of the bipolar pill electrode. We have found that electrode motion is correlated to breathing and cardiac activity. Therefore, because electrode motion is its main noise source, electrode noise will be correlated to the ECG. The impedance signal measured can be used to further reduce the noise i n h igh-resolution esophageal electrocardiography.

3Cat-1 project: a multi-payload CubeSat for scientific experiments and technology demonstrators

ABSTRACT This article introduces 3Cat-1, the first project of the Technical University of Catalonia to build and launch a nano-satellite. Its main scope is to develop, construct, assemble, test and launch into a low Earth orbit a CubeSat with seven different payloads (mono-atomic oxygen detector, graphene field-effect transistor, self-powered beacon, Geiger radiation counter, wireless power transfer (WPT), new topology solar cells and WPT experiment), all fitted in a single-unit CubeSat. On one hand, this is mainly an educational project in which the development of some of the subsystems is carried out by undergraduate and postgraduate students. The satellite demonstrates its capabilities as a cost-effective platform to perform small scientific experiments and to demonstrate some of the new technologies that it incorporates.

Cubesat-based demonstrator for optical earth observation

This paper introduces UPCSat-1, the first project of the Universitat Politecnica de Catalunya to build and launch a pico-satellite. Its main scope is to develop, construct, assembly, test and launch into a Low Earth Orbit a CubeSat that will carry a simple optical payload and some technological demonstrators. On one hand, this is mainly an educational project in which the development of some of the subsystems is carried out by Master Thesis students. On the other hand, the satellite becomes an optimum platform to perform small scientific experiments, and to demonstrate some of the new technologies that it incorporates.

Multichannel front-end for low level instrumentation signals

We have analyzed the conflicting requirements in a system able to measure m differential signals from n single-ended input voltages and propose a novel circuit offering high input impedance, high common-mode rejection ratio, low noise and bandwidth matched to the application.

Ventilation and Heart Rate Monitoring in Drivers using a Contactless Electrical Bioimpedance System

Nowadays, the road safety is one of the most important priorities in the automotive industry. Many times, this safety is jeopardized because of driving under inappropriate states, e.g. drowsiness, drugs and/or alcohol. Therefore several systems for monitoring the behavior of subjects during driving are researched. In this paper, a device based on a contactless electrical bioimpedance system is shown. Using the four-wire technique, this system is capable of obtaining the heart rate and the ventilation of the driver through multiple textile electrodes. These textile electrodes are placed on the car seat and the steering wheel. Moreover, it is also reported several measurements done in a controlled environment, i.e. a test room where there are no artifacts due to the car vibrations or the road state. In the mentioned measurements, the system response can be observed depending on several parameters such as the placement of the electrodes or the number of clothing layers worn by the driver.

Monitoring Drivers’ Ventilation Using an Electrical Bioimpedance System: Tests in a Controlled Environment

As improving road safety is one of the first aims in the automotive world, several new techniques and methods are being researched in recent years. Some of them consist of monitoring the driver behavior to detect non-appropriate states for driving, e.g. drowsy driving or drunk driving. Usually, the appearance of these non-appropriate states is related to changes in several physiological parameters. This work is divided into two main parts. The first one presents an electrical bioimpedance system capable of monitoring the ventilation using textile electrodes. Apart from describing the system, in this part some tests done in a controlled environment are also shown. In the second part of this paper, an enhancement of the system is described and checked using a patient simulator.

Heart Graft Rejection Assessed by Multi-Frequency Electrical Impedance: Human Results

We measured the myocardial electrical impedance with a custom system using an intracavitary catheter. We calculated the impedance differences between the measurement in the right ventricle with the tip of the catheter in contact with the myocardial wall, and the measurement in the right atrium with the catheter in a floating position. Our study includes two groups of patients. Group I was composed of 33 patients who underwent cardiac transplantation. Some patients in this group were measured more than once, so a total of 57 measurement sessions were done with different biopsies results: 0,1A and 3A. Group II included 9 control patients without clinical and echocardiographic evidence of structural heart disease, who underwent an electrophysiologic testing. Results show that estimated myocardial impedance difference between ventricle and atrium is higher in controls than in transplanted patients. Furthermore, moderate cardiac rejection causes a significant decrease in the myocardial impedance, differences are more significant (p<0.001) for the magnitude of impedance at 10 kHz and the phase angle at 300 kHz.

Noise properties in the isoelectric intervals of the ECG: a comparison

The authors have compared the variance and the histogram for the three isoelectric intervals of the ECG of 8 subjects. They have used a spectral filter in order to eliminate the power line frequency. They have found that when the noise variance is low, the histogram is bell shaped and similar for the three intervals. But when the noise variance is high, the histogram does not have any definite shape. When the relative difference between variances for the isoelectric intervals is low, these intervals can be considered as similar. But in some instances, noise histograms for different intervals have rather different variances. The authors have tested their analysis method by adding noise with different amplitude distributions to a clean ECG. They conclude that although the time record gives a clue about when to reject a noisy ECG, the measurement of the noise variance in the three isoelectric intervals would be better. Also, when searching for micropotentials in the PR or ST intervals, the noise behavior in the TP interval is not necessarily representative of the noise in the other intervals.<<ETX>>