Classification of Premature Ventricular Contraction (PVC) based on ECG Signal using Convolutional Neural Network

This study observes one of the ECG signal abnormalities, which is the Premature Ventricular Contraction (PVC). Many studies applied a machine learning technique to develop a computer-aided diagnosis to classify normal and PVC conditions of ECG signals. The common process to obtain information from the ECG signal is by performing a feature extraction process. Since the ECG signal is a complex signal, there is a need to reduce the signal dimension to produce an optimal feature set. However, these processes can remove the information contained in the signal. Therefore, this study process the original ECG signal using a Convolutional Neural Network to avoid losing information. The input data were in the form of both one beat of normal ECG signal or PVC with size 1x200. The classification used four layers of convolutional neural network (CNN). There were eight 1x1 filters used in the input. Simultaneously, 16 and 32 of 1x1 filters were used in the second and the fourth convolutional layers, respectively. Thus the system produced a fully connected layer consisted of 512 neurons, while the output layer consisted of 2 neurons. The system is tested using 11361 beats of ECG data and achieved the highest accuracy of 99.59%, with the 10-fold cross-validation. This study emphasizes an opportunity to develop a wearable device to detect PVC since CNN can be implemented into an embedded system or an IoT based system

QRS Differentiation to Improve ECG Biometrics under Different Physical Scenarios Using Multilayer Perceptron

This article belongs to the Special Issue Electrocardiogram (ECG) Signal and Its Applications.Currently, machine learning techniques are successfully applied in biometrics and Electrocardiogram (ECG) biometrics specifically. However, not many works deal with different physiological states in the user, which can provide significant heart rate variations, being these a key matter when working with ECG biometrics. Techniques in machine learning simplify the feature extraction process, where sometimes it can be reduced to a fixed segmentation. The applied database includes visits taken in two different days and three different conditions (sitting down, standing up after exercise), which is not common in current public databases. These characteristics allow studying differences among users under different scenarios, which may affect the pattern in the acquired data. Multilayer Perceptron (MLP) is used as a classifier to form a baseline, as it has a simple structure that has provided good results in the state-of-the-art. This work studies its behavior in ECG verification by using QRS complexes, finding its best hyperparameter configuration through tuning. The final performance is calculated considering different visits for enrolling and verification. Differentiation in the QRS complexes is also tested, as it is already required for detection, proving that applying a simple first differentiation gives a good result in comparison to state-of-the-art similar works. Moreover, it also improves the computational cost by avoiding complex transformations and using only one type of signal. When applying different numbers of complexes, the best results are obtained when 100 and 187 complexes in enrolment, obtaining Equal Error Rates (EER) that range between 2.79–4.95% and 2.69–4.71%, respectively

A Survey of Wearable Biometric Recognition Systems

The growing popularity of wearable devices is leading to new ways to interact with the environment, with other smart devices, and with other people. Wearables equipped with an array of sensors are able to capture the owner’s physiological and behavioural traits, thus are well suited for biometric authentication to control other devices or access digital services. However, wearable biometrics have substantial differences from traditional biometrics for computer systems, such as fingerprints, eye features, or voice. In this article, we discuss these differences and analyse how researchers are approaching the wearable biometrics field. We review and provide a categorization of wearable sensors useful for capturing biometric signals. We analyse the computational cost of the different signal processing techniques, an important practical factor in constrained devices such as wearables. Finally, we review and classify the most recent proposals in the field of wearable biometrics in terms of the structure of the biometric system proposed, their experimental setup, and their results. We also present a critique of experimental issues such as evaluation and feasibility aspects, and offer some final thoughts on research directions that need attention in future work

A survey of wearable biometric recognition systems

The growing popularity of wearable devices is leading to new ways to interact with the environment, with other smart devices, and with other people. Wearables equipped with an array of sensors are able to capture the owner's physiological and behavioural traits, thus are well suited for biometric authentication to control other devices or access digital services. However, wearable biometrics have substantial differences from traditional biometrics for computer systems, such as fingerprints, eye features, or voice. In this article, we discuss these differences and analyse how researchers are approaching the wearable biometrics field. We review and provide a categorization of wearable sensors useful for capturing biometric signals. We analyse the computational cost of the different signal processing techniques, an important practical factor in constrained devices such as wearables. Finally, we review and classify the most recent proposals in the field of wearable biometrics in terms of the structure of the biometric system proposed, their experimental setup, and their results. We also present a critique of experimental issues such as evaluation and feasibility aspects, and offer some final thoughts on research directions that need attention in future work.This work was partially supported by the MINECO grant TIN2013-46469-R (SPINY) and the CAM Grant S2013/ICE-3095 (CIBERDINE

Seamless Multimodal Biometrics for Continuous Personalised Wellbeing Monitoring

Artificially intelligent perception is increasingly present in the lives of every one of us. Vehicles are no exception, (...) In the near future, pattern recognition will have an even stronger role in vehicles, as self-driving cars will require automated ways to understand what is happening around (and within) them and act accordingly. (...) This doctoral work focused on advancing in-vehicle sensing through the research of novel computer vision and pattern recognition methodologies for both biometrics and wellbeing monitoring. The main focus has been on electrocardiogram (ECG) biometrics, a trait well-known for its potential for seamless driver monitoring. Major efforts were devoted to achieving improved performance in identification and identity verification in off-the-person scenarios, well-known for increased noise and variability. Here, end-to-end deep learning ECG biometric solutions were proposed and important topics were addressed such as cross-database and long-term performance, waveform relevance through explainability, and interlead conversion. Face biometrics, a natural complement to the ECG in seamless unconstrained scenarios, was also studied in this work. The open challenges of masked face recognition and interpretability in biometrics were tackled in an effort to evolve towards algorithms that are more transparent, trustworthy, and robust to significant occlusions. Within the topic of wellbeing monitoring, improved solutions to multimodal emotion recognition in groups of people and activity/violence recognition in in-vehicle scenarios were proposed. At last, we also proposed a novel way to learn template security within end-to-end models, dismissing additional separate encryption processes, and a self-supervised learning approach tailored to sequential data, in order to ensure data security and optimal performance. (...)Comment: Doctoral thesis presented and approved on the 21st of December 2022 to the University of Port

Personality Assessment Using Biosignals and Human Computer Interaction applied to Medical Decision Making

Clinical decision-making for patients with multiple acute or chronic diseases (i.e. multimorbidity) is complex. There is often no ’right’ or optimal treatment due to the potentially harmful effects of multiple interactions between drugs and diseases. This makes it necessary to establish trade-offs between the benefits and risks of different treatment strategies. This means also that there may be high levels of risk and uncertainty when making decisions. One factor that can influence how decisions are made under conditions of risk and uncertainty is the decision maker’s personality. The studies of this dissertation used biosignals and eye-tracking methods and developed pointer tracking techniques to monitor human computer interaction to assess, using machine learning techniques, the individual personality of decision makers. Data acquisition systems were designed and prepared to collect and synchronize: 1) physiological data - electrocardiogram, blood volume pulse and electrodermal activity; 2) human-computer interaction data - pointer movements, eye tracking and pupil diameter; 3) decision-making task data; and 4) personality questionnaire’ results. A set of processing tools was developed to ensure the correct extraction of psychophysiologyrelated features that could manifest personality. These features were combined by several machine learning algorithms to predict the Big-Five personality traits: Openness, Conscientiousness, Extraversion, Agreeableness and Conscientiousness. The five personality traits were well modelled by, at least, one of the sets of features extracted. With a sample of 88 students, features from the pointer movements in online surveys predicted four personality traits with a mean squared error (MSE)<0.46. The blood volume pulse responses in a decision-making task trained in a distinct sample of 79 students predicted four personality traits with a MSE<0.49. The application of the personality models based on the pointer movements in the personality questionnaire in a sample of 12 medical doctors achieved a MSE<0.40 for three personality traits. These were the best results achieved in each context of this thesis. The outcomes of this work demonstrate the huge potential of broader models that predict personality through human behaviour, with possible application in a wide variety of fields, such as human resources, medical research studies or machine learning approaches