Diego P. Morales

• PhD Electronic Engineering
• Full Professor at University of Granada

The growing spread of misinformation in recent years has become a concern for both governments and citizens, highlighting the need to verify the origin, authenticity and history of media files. This relevant information, commonly referred to as provenance, provides media consumers with assurance that the content originates from a known and trusted...

Hand gesture recognition (HGR) is a convenient and natural form of human–computer interaction. It is suitable for various applications. Much research has already focused on wearable device-based HGR. By contrast, this paper gives an overview focused on device-free HGR. That means we evaluate HGR systems that do not require the user to wear somethin...

The increase of the global population, climate change and the scarcity of resources are some of the reasons why the improvement of the agricultural sector has become a crucial issue for the future of our society. Recently, the growth of Internet of Things (IoT) has meant a revolution in many industries, including the agricultural sector, where the...

Simultaneous Localization and Mapping (SLAM) algorithms are crucial for enabling agents to estimate their position in unknown environments. In autonomous navigation systems, these algorithms need to operate in real-time on devices with limited resources, emphasizing the importance of reducing complexity and ensuring efficient performance. While SLA...

In the evolution of pervasive electronics, it is imperative to significantly reduce the energy consumption of power systems and embrace sustainable materials and fabrication processes with minimal carbon footprint. Within this context, thermoelectric generators (TEGs) have garnered substantial attention in recent years because of the readily availa...

In the field of eXplainable Artificial Intelligence (XAI), the generation of counterfactuals is a promising method for human-interpretable explanations. A counterfactual explanation describes a causal situation in the form: “If X had not occurred, Y would not have occurred”. In this work, we study the generation of visual counterfactuals in the lat...

Hybrid inverters are gaining importance because they combine the benefits of regular solar inverters with the flexibility of battery inverters. For increasing their deployment, the aim is to make them efficient and economically viable. This requires techniques that raise the output voltage of the photovoltaic strings. Hence, the auxiliary power sup...

Please cite this article as: D.M. Rodríguez, M.P. Cuéllar and D.P. Morales, On the fusion of soft-decision-trees and concept-based models, Applied Soft Computing (2024), doi: https://doi. Abstract In the field of eXplainable Artificial Intelligence (XAI), the generation of interpretable models that are able to match the performance of state-of-the-...

Meta-few-shot learning algorithms, such as Model-Agnostic Meta-Learning (MAML) and Almost No Inner Loop (ANIL), enable machines to learn complex tasks quickly with limited data and based on previous experience. By maintaining the inner loop head of the neural network, ANIL leads to simpler computations and reduces the complexity of MAML. Despite it...

A novel laser‐induced graphene (LIG) resistive relative humidity (RH) sensor is successfully fabricated by direct laser writing on a common natural cork sheet. In this work, a straightforward fabrication is presented where LIG, porous multilayer graphene, is generated by a laser photothermal process on a carbon‐based substrate, in this case, an agg...

This work presents the optimization of the fabrication procedure for laser-induced graphene (LIG) electrodes intended for biopotentials acquisition. The results presented in this study demonstrate a significant improvement with respect to the performance obtained for other LIG-based electrodes previously reported in the literature. In particular, w...

Interpretable deep learning models are increasingly important in domains where transparent decision-making is required. In this field, the interaction of the user with the model can contribute to the interpretability of the model. In this research work, we present an innovative approach that combines soft decision trees, neural symbolic learning, a...

Fractal‐like geometries applied to biosignal‐electrodes design show great potential for enhancing the signal acquisition of sensing systems. This study reports a novel approach for flexible, silver‐free, and dry fractal‐like electrodes based on Laser‐Induced Graphene (LIG) obtained through laser photothermal processing of a commercial polyimide fil...

This study presents a pioneering approach to fabricating single-layer Frequency Selective Surfaces (FSS) using Laser-Induced Graphene (LIG). The FSS structure proposed consists of periodic resistive patterns of LIG synthesized through a one-step laser photothermal process directly on the surface of a thin polyimide substrate. The structural and ele...

In this work, a secure architecture to send data from an Internet of Things (IoT) device to a blockchain-based supply chain is presented. As is well known, blockchains can process critical information with high security, but the authenticity and accuracy of the stored and processed information depend primarily on the reliability of the information...

Power electronics is experiencing a strong growth, driven by industrial demand for applications as diverse as wall adapters and renewable energy. In addition to topologies, semiconductors or control, there is also a need for research in magnetics, such as planar transformers, which are very useful for certain applications where a low converter prof...

This work presents a novel approach for the fabrication of Frequency Selective Surfaces (FSS) through the direct laser scribing of a flexible polyimide film. This technique enables both the fast and high accurate fabrication of the lossy FSS patterns and the precise control over their resistivity. First, the resulting laser-induced material is stru...

In many industrial or healthcare contexts, keeping track of the number of people is essential. Radar systems, with their low overall cost and power consumption, enable privacy-friendly monitoring in many use cases. Yet, radar data are hard to interpret and incompatible with most computer vision strategies. Many current deep learning-based systems a...

In this work, gas sensors using laser-reduced graphene oxide (LrGO) as sensitive layer have been fabricated and studied. The laser-synthetized material were structurally and electrically characterized by means of Scanning Electron Microscopy (SEM), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and the four-point contact method. The gas...

Blockchain networks, given that they are not based on power-hungry proof-of-work methods, can be used in smart grid applications, in particular in the tradable green certificates use case. Thanks to the Blockchain and the smart contracts implemented, certificates can be tracked and exchanged between entities without the intervention of third partie...

The security of Industrial Internet of Things (IIoT) systems is a challenge that needs to be addressed immediately, as the increasing use of new communication paradigms and the abundant use of sensors opens up new opportunities to compromise these types of systems. In this sense, technologies such as Trusted Execution Environments (TEEs) and Hardwa...

This ADACORSA demonstrator focuses on the implementation of a fail-operational avionics architecture combining Commercial Off-The-Shelf (COTS) elements from the automotive, the aerospace and the artificial intelligence world. A collaborative sensor setup (Time-of-Flight camera and FMCW RADAR from Infineon Technologies, stereo camera, LiDAR, IMU and...

Microservice architectures exploit container-based virtualized services, which rarely use hardware-based cryptography. A trusted platform module (TPM) offers a hardware root for trust in services that makes use of cryptographic operations. The virtualization of this hardware module offers high usability for other types of service that require TPM f...

One of the key challenges in the field of flexible electronics relies on finding conductive materials that can withstand bending and stretching stresses while maintaining their performance. In this context, this work presents a comparative study of laser-induced conductive materials from the direct laser-scribing of two commercial flexible films: t...

Sensor fusion is a critical aspect in autonomous drone navigation as several tasks, such as object detection and self-pose estimation, require combining information from heterogeneous sources. The performance of these solutions depends on several factors, such as the characteristics of the sensors and the environment, as well as the computing platf...

Energy Reports Volume 9, December 2023, Pages 3222-3234 Research paper Resonant hybrid flyback: A novel topology with wide voltage range for DC microgrid applications Author links open overlay panelJuan Cruz-Cozar a, Alfredo Medina-Garcia a, Diego P. Morales b, Noel Rodriguez b Show more Outline Share Cite https://doi.org/10.1016/j.egyr.2023.02.027...

Here, we propose a microfluidic paper-based analytical device (µPAD) implemented with a near-field communication (NFC) tag as a portable, simple and fast colorimetric method for glutathione (GSH) determination. The proposed method was based on the fact that Ag+ could oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into oxidized blue TMB. Thus, the pre...

Vital signs estimation provides valuable information about an individual’s overall health status. Gathering such information usually requires wearable devices or privacy-invasive settings. In this work, we propose a radar-based user-adaptable solution for respiratory signal prediction while sitting at an office desk. Such an approach leads to a con...

This paper presents a low-cost, self-recoverable, double-node upset tolerant latch aiming at nourishing the lack of these devices in the state of the art, especially featuring self-recoverability while maintaining a low-cost profile. Thus, this D-latch may be useful for high reliability and high-performance safety-critical applications as it can de...

Hardware Security Modules (HSM) serve as a hardware based root of trust that offers physical protection while adding a new security layer in the system architecture. When combined with decentralized access technologies as Blockchain, HSM offers robustness and complete reliability enabling secured end-to-end mechanisms for authenticity, authorizatio...

Functional nanomaterials have become one of the most fascinating fields in nanotechnology [...]

The extensive use of smartphones with point-of-care (POC) applications has boosted the development of what is commonly known as Healthcare 4.0. The ability to track biomarker parameters has become a critical part of monitoring the progression of certain diseases, with a potential application in a large population group. In this line, this work pres...

There is a growing interest in pushing computation to the Edge, especially the problem-solving abilities of Artificial Neural Networks (ANNs). This paper presents a simplified method to obtain a Ternary Neural Network based on the Multilayer Perceptron. The method is focused on resource-constrained devices, where memory, computing power, and batter...

In this work a versatile hardware platform based on reconfigurable devices is presented. This platform it intended for the acquisition of multiple biosignals, only requiring a reconfiguration to switch applications. This prototype has been combined with graphene-based, flexible electrodes to cover the application to different biosignals presented i...

This paper presents and implements a novel remote attestation method to ensure the integrity of a device applicable to decentralized infrastructures, such as those found in common edge computing scenarios. Edge computing can be considered as a framework where multiple unsupervised devices communicate with each other with lack of hierarchy, requesti...

Two novel metal-organic frameworks (MOFs), based on dysprosium as the metal and the 5-aminoisophthalic acid (5aip) ligand, have been solvothermally synthesized, with the aim of studying and modulating their luminescence properties according to the variation of solvent in the structure. These materials display intense photo-luminescence properties i...

This case report presents a real example of a study which introduces the use of reconfig- urable platforms in the teaching of electronics engineering to establish a bridge between theory and practice. This gap is one of the major concerns of the electronics engineering students. Different strategies, such as simulation tools or breadboard implement...

Technological advances and scalability are leading Human-Computer Interaction (HCI) to evolve towards intuitive forms, such as through gesture recognition. Among the various interaction strategies, radar-based recognition is emerging as a touchless, privacy-secure, and versatile solution in different environmental conditions. Classical radar-based...

Herein, we present the syntheses of a novel coordination polymer (CP) based on the perylene-3,4,9,10-tetracarboxylate (pery) linkers and sodium metal ions. We have chosen sodium metal center with the aim of surmising the effect that the modification of the metal ion may have on the relative humidity (RH) experimental measurements of the material. W...

The name Edge Intelligence , also known as Edge AI , is a recent term used in the last few years to refer to the confluence of Machine Learning, or broadly speaking Artificial Intelligence, with Edge Computing. In this manuscript, we revise the concepts regarding Edge Intelligence, such as Cloud, Edge and Fog Computing, the motivation to use Edge I...

In this work a versatile hardware platform based on reconfigurable devices is presented. This platform it intended for the acquisition of multiple biosignals, only requiring a reconfiguration to switch applications. This prototype has been combined with graphene-based, flexible electrodes to cover the application to different biosignals presented i...

The recent release of the standard USB-PD 3.1 specifies variable output voltages from 5 V to 48 V featuring a step forward towards a universal adaptor but rising new challenges for the converter topologies used up to now. In such applications, a first AC-DC stage is followed by a DC-DC stage. In this paper, emerging WBG technologies are applied to...

Presentation for the defense of my PhD Thesis

MOTIVATION AND OBJECTIVES The power supplies or power converters are required in many applications to convert between the AC of the distribution grid to AC or DC at different voltage and current levels required by the electric loads. Each applica-tion may include different conversion steps and at different voltage levels. In every conversion step...

The interfaces between users and systems are evolving into a more natural communication, including user gestures as part of the interaction, where air-writing is an emerging application for this purpose. The aim of this work is to propose a new air-writing system based on only one array of ultrasonic transceivers. This track will be obtained based...

The switching loss of the secondary side rectifiers in LLC resonant converters can have a noticeable impact on the overall efficiency of the complete power supply and constrain the upper limit of the optimum switching frequencies of the converter. Two are the main contributions to the switching loss in the secondary side rectifiers: on the one hand...

This work studies the feasibility of a novel two-step algorithm for infrastructure and object positioning, using pairwise distances. The proposal is based on the optimization algorithms, Scaling-by-Majorizing-a-Complicated-Function and the Limited-Memory-Broyden-Fletcher-Goldfarb-Shannon. A qualitative evaluation of these algorithms is performed fo...

Recent market trends are shaping the direction of power adaptors development. On the one hand, USB-PD standard [1] that allows the reuse of power adaptors for multiple devices, thus reducing the electronic waste generated [2]; on the other hand, fast battery charging features for mobile devices bring the need for higher adaptor power levels, result...

In this paper, the design of a new complete power supply for server applications is discussed. The main constraints of the new solution are the very high peak efficiency, the long holdup time and the maximum outer dimension. The PSU is comprised of a front-end ACDC bridgeless totem-pole PFC and a back-end DCDC half-bridge LLC. Due to the extended h...

Método, dispositivo y sistema para el almacenamiento, la codificación y la decodificación de información basada en códigos con capacidad de detección de errores. Se describe un dispositivo compuesto por al menos dos capas, una de las cuales es invariante y contiene un código visual con capacidad de corregir errores, y al menos una capa que es varia...

There have been significant advances regarding target detection in the autonomous vehicle context. To develop more robust systems that can overcome weather hazards as well as sensor problems, the sensor fusion approach is taking the lead in this context. Laser Imaging Detection and Ranging (LiDAR) and camera sensors are two of the most used sensors...

Data acquisition and treatment are key issues for any Deep Learning (DL) technique, especially in computer vision tasks. A big effort must be done for the creation of labeled datasets, due to the time this task requires and its complexity in cases where different sensors must be used. This is the case of radar imaging applications, where radar data...

In 1971, Prof. L. Chua theoretically introduced a new circuit element, which exhibited a different behavior from that displayed by any of the three known passive elements: the resistor, the capacitor or the inductor. This element was called memristor, since its behavior corresponded to a resistor with memory. Four decades later, the concept of mem-...

In this article, a power converter based on an asymmetrical half-bridge flyback topology is analyzed and optimized for small form factor and fast-charging power adaptors. Two resonant control methods, taking advantage of the forward and flyback characteristics of the converter, as well as the benefits of each of them depending of the operation poin...

CNT-Based RC networks are described with the purpose of showing empirical findings on the influence of the interdigitated electrodes (IDE) spacing, the dispersant compound and the number of deposited layers, on the impedance magnitude and phase of the CNTs. Additionally, we propose use-cases for these networks, applying them to the realization of f...

The aim of this work is to prove that it is possible to develop a system able to detect gestures based only on ultrasonic signals and Edge devices. A set of 7 gestures plus idle has been defined, being possible to combine them to increase the recognized gestures. In order to recognize them, Ultrasound transceivers will be used to detect the 2 dimen...

In this communication we present the design, simulation and implementation of a floating flux-controlled meminductor emulator based on the Riordan gyrator. Firstly, the circuit is presented theoretically, from its original version to emulate inductors to its adaptation for floating meminductors. Once its theoretical equations are presented, using S...

We report a simple, rapid, low-resource and one-step method for formation of fluorescent silicon nanodots (SNDs) in a microfluidic paper-based analytical device (µPAD) incorporated in a reusable, portable and flexible heater for determination of total carbohydrates. The synthesis of SNDs is based on the redox reaction between (3-aminopropyl) trieth...

Salivary pH is one of the indicators of the dental health of a person. To enable fast and easy dental health observations, we developed a flexible capacitive pH sensor using graphene oxide (GO) sensing layer on the laser-induced graphene (LIG) electrode produced from a polyimide (PI) film acting both as LIG precursor material and substrate. Cyclic...

Laser reduced graphene oxide (LrGO) has been considered as temperature sensor and its thermal sensitivity has been studied as a function of the reduction laser power level. To do so, LrGO squares of 1 cm 2 on a flexible substrate have been fabricated. We found that for the lower tested power (50 mW), both the nominal resistance (about 500 Ω) and te...

In this letter, we present the extension of a previous work on a cost-effective method for fabricating highly sensitive humidity sensors on flexible substrates with a reversible response, allowing precise monitoring of the humidity threshold. In that work we demonstrated the use of three-dimensional metal-organic framework (MOF) film deposition bas...

This work presents an innovative application of carbon dots (Cdots) nanoparticles as sensing layer for relative humidity detection. The developed sensor is based on interdigitated capacitive electrodes screen printed on a flexible transparent polyethylene terephthalate (PET) film. Cdots are deposited on top of these electrodes. An exhaustive charac...

Although the number of Internet of Things devices increases every year, efforts to decrease hardware energy demands and to improve efficiencies of the energy-harvesting stages have reached an ultra-low power level. However, no current standard of wireless communication protocol (WCP) can fully address those scenarios. Our focus in this paper is to...

This work demonstrates a cost-effective manufacturing method of flexible and fully printed microheaters, using carbon nanotubes (CNTs) as the heating element. Two different structures with different number of CNT layers have been characterized in detail. The benchmarking has been carried out in terms of maximum operating temperature, as well as nom...

RF energy harvesting (RFEH) has recently become part of the alternatives for powering wireless sensor networks. Our focus in this paper was to introduce a design, MSwitch, able to use off-the-shelf dc/dc converters for running a real and self-powered Internet of Things (IoT) application. MSwitch is an RF dual-band energy harvesting stage employing...

In this work, we presented the design and simulation of a new flux-controlled meminductor emulator based on a modified version of the well-known Antoniou’s inductor simulator circuit. The constitutive theoretical equations of meminductance are presented and subsequently correlated with the electrical behavior of Antoniou’s circuit, hence illustrati...

In this paper flexible printed electrodes applicable to wearable electronics are presented. Using innovative materials as Laser Induced Graphene (LIG) and printed electronics, three type of electrodes based in LIG, silver chloride and carbon inks have been compared during the acquisition of bipotentials as electrocardiogram, electromyogram and elec...

Herein we present, for the first time, a 2D-MOF based on copper and 4-hydroxypyrimidine-5-carbonitrile as linker. Each MOF layer is perfectly flat and neutral, as is the case for graphene. High pressure X-Ray diffraction measurements reveal that such layered structure can be modulated between 3.01 to 2.78 Å interlayer separation, with an evident pi...

The parasitic capacitances of modern Si SJ MOSFETs are characterized by their non-linearity. At high voltages the total stored energy Eoss(VDC) in the output capacitance Coss(v) differs substantially from the energy in an equivalent linear capacitor Coss(tr) storing the same amount of charge. That difference requires the definition of an additional...

In this paper, we present a comparative study of a cost-effective method for the mass fabrication of electrodes to be used in thin-film flexible supercapacitors. This technique is based on the laser-synthesis of graphene-based nanomaterials, specifically, laser-induced graphene and reduced graphene oxide. The synthesis of these materials was perfor...

A portable reconfigurable platform for hemoglobin determination based on inner filter quenching of room-temperature phosphorescent carbon dots (CDs) in the presence of H2O2 is described. The electronic setup consists of a light-emitting diode (LED) as the carbon dot optical exciter and a photodiode as a light-to-current converter integrated in the...

This work presents a novel approach for the fabrication of Electrochemical Capacitors (ECs) based on the screen-printing of a commercial carbon-based conductive ink on flexible substrates. This technique enables the fast and cost-effective production of ECs with high flexibility and outstanding performance over bending states and voltage cycling, a...

The irruption of Internet of Things and 5G in our society comes along with several technological challenges to overcome. From an overall perspective, the low-cost and environmental friendliness of these technologies need to be ensured for their universal deployment in different areas, starting with the sensors and finishing with the power sources....

Radio frequency identification (RFID) security is a relevant matter. The wide spread of RFID applications in the general society and the persistent attempts to safeguard it confirm it, especially since its use involves payments and the store or transmission of sensitive information. In this contribution, we present an innovative solution for improv...