Artículos (Electrónica y Electromagnetismo)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10839

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The 1st Workshop on Quantum in Consumer Technology At IEEE Quantum Week 2022
(IEEE, 2023-02-09) Sotelo, Rafael; Wang, Jingbo; Nakamura, Yuichi; Farouk, Ahmed; Arjona, Rosario; Andraca, Salvador Venegas; James, Alex; Venegas-Gomez, Araceli; Gonzalez, Bill; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo
The Workshop on Quantum in Consumer Technology (QCT) at IEEE Quantum Week 2022 was an enlightening event, bringing together experts from a variety of fields to discuss the current state and future potential of quantum technology in consumer applications.
Dynamic Vision With Single Photon Detectors: A Discrete DVS Architecture Using Asynchronous Sensor Front-Ends
(Institute of Electrical and Electronics Engineers, 2025-01-01) Gómez Merchán, Ruben; Leñero Bardallo, Juan Antonio; La Rosa Vidal, Rafael de; Rodríguez Vázquez, Ángel Benito; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo
This paper reports an architectural concept for achieving dynamic vision with Single-Photon Avalanche Diode (SPAD) detectors. This new concept, demonstrated through a dedicated proof-of-concept sensor chip and an associated camera module, addresses the challenge of large data volume due to frequent laser exposures by optimizing data processing via temporal-contrast-based event filtering. The manuscript analyzes trade-offs between contrast sensitivity, latency, and noise in the proposed discrete DVS architecture and validates the proposal through experimental results obtained with the camera module. The proposed sensor has different operation modes that show potential for augmented reality applications. Benchmarking comparison with competing SPAD-based vision sensors shows latency and power consumption advantages.
Design of Broadband Aperture-Coupled Microstrip Antenna Arrays With Differential Feeding
(Institute of Electrical and Electronics Engineers Inc., 2024) Delgado Lozano, Ignacio María; Fernández Prieto, Armando; Losada Torres, Vicente; Boix, R. R.; Medina Mena, Francisco; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This paper proposes the design of broadband microstrip antennas fed by differential microstrip lines. The designed broadband antennas are composed of two capacitively coupled rectangular stacked patches excited through a dog-bone shaped aperture by short-circuited differential microstrip lines. The short-circuited lines are symmetrically located with respect to the apertures so that their differential-mode (DM) naturally excites the aperture, while their common-mode (CM) is intrinsically rejected. The DM design of the antennas is based on an equivalent second-order filter circuit consisting of two capacitively coupled parallel LC resonators, which helps to ensure the DM broadband impedance matching of the antenna. Two different 2 × 2 arrays using the proposed antennas have been designed, fabricated and measured, one involving four 180° hybrids and three power dividers in the feeding network, the other involving one 180° hybrid and six power dividers. Bandwidths larger than 25%, gains around 12 dBi and cross-polarization below -25 dB have been achieved by the two arrays at a center frequency of 5.5 GHz.
Coulomb Driven Electro-Convection within Two Stacked Layers of Miscible Dielectric Liquids †
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Traore, P.; Pérez Izquierdo, Alberto Tomás; Mondal, S.; Bhattacharya, A.; Vázquez González, Pedro Ángel; Yan, Z.; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada III; Labex Interactifs. Francia; Ministerio de Ciencia e Innovación (MICIN). España
This article investigates the behavior of two parallel layers of different miscible dielectric liquids enclosed and sandwiched between two electrodes. By applying an electric potential to one electrode while grounding the other, electro-convection occurs when the electric Rayleigh number exceeds a critical value, setting the fluid into motion and resulting in rapid mixing between the two liquids. A numerical model is developed to account for the varying ionic mobility and permittivity of the two liquids, considering their evolution based on the relative concentration field. The simulations confirm that electro-convection significantly enhances the mixing between the two liquids, as expected. Additionally, intriguing ripples are observed near the initial interface during the early stages of electro-convection instability growth. To explain and describe the flow dynamics in terms of stability analysis, a semi-analytical model is presented. This study provides insights into the mixing behavior and flow dynamics of miscible dielectric liquids under the influence of electro-convection. The findings contribute to a better understanding of the underlying mechanisms and can be valuable for applications such as microfluidics, energy conversion, and mixing processes. Further research is encouraged to explore additional parameters and optimize the control of electro-convection for practical applications.
Triboelectric pixels as building blocks for microscale and large-area integration of drop energy harvesters
(Cell Press, 2024-10-03) Ghaffarinejad, Ali; García Casas, Xabier; Núñez-Gálvez, Fernando; Budagosky Marcilla, Jorge Alejandro; Fortio Godinho, Vanda Cristina; López Santos, Carmen; Sánchez Valencia, Juan Ramón; Barranco Quero, Ángel; Borrás, Ana; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Física Aplicada I; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE). H2020
Triboelectric nanogenerators (TENGs) are the most promising technology for harvesting energy from low-frequency liquid flows and impacts such as rain droplets. However, current drop energy harvester technologies suffer from low output power due to limitations in triboelectric materials, suboptimal device designs, and the inability to fully capture the kinetic energy of falling drops. This article introduces a microscale TENG capable of efficiently converting drop impact energy into electrical power in a single, rapid step. The device features a capacitive structure that enhances energy conversion through instantaneous capacitance changes when the drops contact the submillimetric top electrodes. This compact design establishes a path toward the development of dense arrays and rain panels and is adaptable to various liquids, scales, triboelectric surfaces, and thin-film configurations, including flexible and transparent materials.
Nanoadditives to mitigate jamming in cohesive granular media
(Elsevier, 2025) Durán Olivencia, Francisco José ; Martín Alfonso, Manuel Antonio; Pontiga Romero, Francisco de Paula; Soria del Hoyo, Carlos; Moreno González, H.; Valverde Millán, José Manuel; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo
Handling and conveying cohesive granular media are common challenges for many industries, which demand smooth and uninterrupted granular flows. Cohesion settles at the cores of these problems, especially at high temperatures, when it rises sharply and flow patterns become intermittent; then, jamming, halts, and shutdowns. Here, we explore shielding limestone particles with nanoadditives to mitigate the adverse effect of cohesion, especially at high temperatures. The work focuses on concentrated solar plants assisted by the calcium looping cycle, a high-temperature environment plagued with jamming vulnerabilities. Experiments analyze the evolution of tensile strength as samples expand and fluidize freely, using three nanomaterials to coat fine limestone powders: silica, titania, and alumina. To investigate the efficacy of these coatings, samples were preconsolidated (up to 2 kPa) before fluidizing at high temperatures (up to 500 ◦C) — conditions that soften the contacts and cause cohesion to escalate. The results showed how discrete layers of nanoadditives shape stiffer surfaces, preventing particles from softening at high temperatures, and thereby limiting the contact area dilation that fuels cohesion. Coatings were prepared considering the optimal amount of nanoadditives to introduce minimal inert material. Concentrations below 1 wt % were enough to ensure uniform coatings and promote easy-flow regimes. Yet at 500 ◦C, only alumina coatings achieved easy-flow dynamics, offering a sintering shielding effect that reduces the rise in tensile strength up to 62 %. This is an outstanding conclusion to mitigate jamming in fine powders, which is paramount for a broad spectrum of granular processes that require transporting and storing cohesive granular media at high temperatures.
PUF-derived IoT identities in a zero-knowledge protocol for blockchain
(Elsevier, 2020-03) Prada Delgado, Miguel Ángel; Baturone Castillo, María Iluminada; Dittmann, Gero; Jelitto, Jens; Kind, Andreas; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Agencia Estatal de Investigación. España
As the internet of things moves into increasingly sensitive domains, connected devices need to be secured against data manipulation and counterfeiting. Where the underlying business processes involve multiple independent parties, a blockchain platform can provide a common source of truth. If changes to the common state depend on IoT devices, the authenticity and integrity of the IoT input must be ensured. Employing a blockchain platform for authenticating devices makes the process independent of the device manufacturer. This paper shows how cryptographic keys derived from a device's physical fingerprint can be employed in a zero-knowledge protocol to authenticate a device. As the keys are regenerated at boot time rather than stored, the approach does not need an expensive secure element. An efficient implementation enables even lightweight devices to prove their identity and sign messages. Experimental results demonstrate the robustness of the approach.
Application specific integrated circuit solution for multi-input multi-output piecewise-affine functions
(John Wiley and Sons Ltd, 2016-01) Brox Jiménez, María; Martínez Rodríguez, Macarena Cristina; Tena Sánchez, Erica; Baturone Castillo, María Iluminada; Acosta Jiménez, Antonio José; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Tecnología Electrónica; European Commission (EC); Ministerio de Economía y Competitividad (MINECO). España; Consejo Superior de Investigaciones Científicas (CSIC)
This paper presents a fully digital architecture and its application specific integrated circuit implementation for computing multi-input multi-output (MIMO) piecewise-affine (PWA) functions. The work considers both PWA functions defined over regular hyperrectangular and simplicial partitions of the input domains and also lattice PWA representations. The proposed architecture is able to implement PWA functions following different realization strategies, using a common structure with a minimized number of blocks, thus reducing power consumption and hardware resources. Experimental results obtained with application specific integrated circuit (ASIC) integrated in a 90-nm complementary metal-oxide semiconductor standard technology are provided. The proposed architecture is compared with other digital architectures in the state of the art habitually used to implement model predictive control applications. The proposal is superior in power consumption (saving up to 86%) and economy of hardware resources (saving up to 40% in comparison with a mere replication of the three representations) to other proposals described in literature, being ready to be used in applications where high-performance and minimum unitary cost are required.
A Methodology for Optimized Design of Secure Differential Logic Gates for DPA Resistant Circuits
(Institute of Electrical and Electronics Engineers, 2014-06) Tena Sánchez, Erica; Castro, Javier; Acosta Jiménez, Antonio José; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Consejo Superior de Investigaciones Científicas (CSIC); Gobierno de España; Universidad de Sevilla. TIC180: Diseño de Circuitos Integrados Digitales y Mixtos
Cryptocircuits can be attacked by third parties using differential power analysis (DPA), which uses power consumption dependence on data being processed to reveal critical information. To protect security devices against this issue, differential logic styles with (almost) constant power dissipation are widely used. However, to use such circuits effectively for secure applications it is necessary to eliminate any energy-secure flaw in security in the shape of memory effects that could leak information. This paper proposes a design methodology to improve pull-down logic configuration for secure differential gates by redistributing the charge stored in internal nodes and thus, removing memory effects that represent a significant threat to security. To evaluate the methodology, it was applied to the design of AND/NAND and XOR/XNOR gates in a 90 nm technology, adopting the sense amplifier based logic (SABL) style for the pull-up network. The proposed solutions leak less information than typical SABL gates, increasing security by at least two orders of magnitude and with negligible performance degradation. A simulation-based DPA attack on the Sbox9 cryptographic module used in the Kasumi algorithm, implemented with complementary metal-oxide-semiconductor, SABL and proposed gates, was performed. The results obtained illustrate that the number of measurements needed to disclose the key increased by much more than one order of magnitude when using our proposal. This paper also discusses how the effectivenness of DPA attacks is influenced by operating temperature and details how to insure energy-secure operations in the new proposals.
DPA vulnerability analysis on Trivium stream cipher using an optimized power model
(Institute of Electrical and Electronics Engineers, 2015-07-30) Tena Sánchez, Erica; Acosta Jiménez, Antonio José; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Consejo Superior de Investigaciones Científicas (CSIC); Gobierno de España; Universidad de Sevilla. TIC180: Diseño de Circuitos Integrados Digitales y Mixtos
In this paper, a Differential Power Analysis (DPA) vulnerability analysis on Trivium stream cipher is presented. Compared to the two previously presented DPA attacks on Trivium, we retrieve the whole key without making any hypothesis during the attack. An optimized power model is proposed allowing the power trace acquisition without making any algorithmic-noise removement thus simplifying the attack strategy considerably. The theoretical vulnerability analysis is presented and then checked developing a simulation-based DPA attack on a standard CMOS Trivium implementation in a 90nm TSMC technology. The results show that our attack is successful for random keys, saving in computer resources and time respecting to previously-reported attacks. The attack is independent on technology used for the implementation of Trivium and can be used to measure the security of novel Trivium implementations.
Resonantly induced transparency for metals with low angular dependence
(American Institute of Physics, 2016-12-15) Camacho Aguilar, Miguel; Hibbins, Alastair P.; Sambles, J. Roy; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Engineering and Physical Sciences Research Council (UK); Universidad de Sevilla. TIC112: Microondas
Thin (sub skin-depth) metal layers are known to almost completely reflect radiation at microwave frequencies. It has previously been shown that this can be overcome at resonance via the addition of closely spaced periodic structures on either side of the film. In this work, we have extended the original one-dimensional impedance mechanism to the use of two-dimensional periodic structures both experimentally and analytically using an equivalent circuit approach. The resulting device shows experimentally a low (<5% relative frequency shift) dependence in both angle of incidence and polarisation. We also show that the same principle can be used to transmit through a thicker (∼μm) perfectly conducting film perforated with a non-diffracting (short pitch) array of subwavelength holes with the cut-off frequency above 900 GHz showing resonant transmissivities in the 20–30 GHz range above 40%.
A single inverse-designed photonic structure that performs parallel computing
(Springer Nature, 2021-03-05) Camacho Aguilar, Miguel; Edwards, Brian; Engheta, Nader; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Engheta, Nader; Office of Naval Research (ONR). United States; Universidad de Sevilla. TIC112: Microondas
In the search for improved computational capabilities, conventional microelectronic computers are facing various problems arising from the miniaturization and concentration of active electronics. Therefore, researchers have explored wave systems, such as photonic or quantum devices, for solving mathematical problems at higher speeds and larger capacities. However, previous devices have not fully exploited the linearity of the wave equation, which as we show here, allows for the simultaneous parallel solution of several independent mathematical problems within the same device. Here we demonstrate that a transmissive cavity filled with a judiciously tailored dielectric distribution and embedded in a multi-frequency feedback loop can calculate the solutions of a number of mathematical problems simultaneously. We design, build, and test a computing structure at microwave frequencies that solves two independent integral equations with any two arbitrary inputs and also provide numerical results for the calculation of the inverse of four 5 x 5 matrices.
Logic Minimization and Wide Fan-In Issues in DPL-Based Cryptocircuits Against Power Analysis Attacks
(Wiley, 2019-02) Tena Sánchez, Erica; Acosta Jiménez, Antonio José; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Consejo Superior de Investigaciones Científicas (CSIC); Gobierno de España; Universidad de Sevilla. TIC180: Diseño de Circuitos Integrados Digitales y Mixtos
This paper discusses the use of logic minimization techniques and wide fan-in primitives and how the design and evaluation of combinational blocks for full-custom dual-precharge-logic-based cryptocircuits affect security, power consumption, and hardware resources. Generalized procedures for obtaining optimized solutions were developed and applied to the gate-level design of substitution boxes, widely used in block ciphers, using sense-amplifier–based logic in a 90-nm technology. The security of several proposals was evaluated with simulation-based correlation power analysis attacks, using the secret key measurements to disclosure metric. The simulation results showed increased security-power-delay figures for our proposals and, surprisingly, indicated that those solutions which minimized area occupation were both the most secure and the most power-efficient.
Alternative General Fitting Methods for Real-Time Cell-Count Experimental Data Processing
(Institute of Electrical and Electronics Engineers, 2020-07-20) Serrano Viseas, Juan Alfonso; Pérez García, Pablo; Huertas Sánchez, Gloria; Yúfera García, Alberto; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICINN). España
This paper reports two general methods for extraction of cell-electrode electrical model parameters in cell culture (CC) assays. The presented approaches can be applied to CC assays based on electrical cell-substrate impedance spectroscopy (ECIS) technique for real-time supervision, providing the cell number per square centimeter, i.e., the cell density, as main result. Both of the proposed methods - minimization of system equations and data predictive model - search, during the experiment, the optimum values of the electrical model parameters employed for the electrode-cell model. The results of this search enable a fast and efficient calculation of the involved cell-electrode model parameters and supply real-time information on the cell number. For the sake of experimental validation, we applied the proposed methods to practical CCs in cell growth assays with a cell line of AA8 Chinese hamster ovarian fibroblasts and the Oscillation Based Test technique for bioimpedance measurements. These methods can be easily extrapolated to any general cell lines and/or other bioimpedance test methodologies.
Bioimpedance Spectroscopy-Based Edema Supervision Wearable System for Noninvasive Monitoring of Heart Failure
(Institute of Electrical and Electronics Engineers, 2023-05-17) Fernández Scagliusi, Santiago Joaquín; Giménez Miranda, Luis; Pérez García, Pablo; Martín Fernández, Daniel; Medrano Ortega, Francisco Javier; Huertas Sánchez, Gloria; Yúfera García, Alberto; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Medicina; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Universidad de Sevilla. Departamento de Biología Celular; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Instituto de Salud Carlos III
Heart failure (HF) is a complex syndrome in which the heart is unable to pump enough blood containing oxygen and nutrients to meet the body's demands. HF is the leading cause of hospitalization for patients over 65 years of age. After a patient is diagnosed with HF, the mortality rate is 50% within the first five years. Presently, there are no unanimous diagnostic criteria for HF. Bioimpedance (BI) analysis has been proposed in recent years as a technique to detect one of the main symptoms: changes in body volume due to edema. This research presents a portable device (Volum), capable of performing real-time BI measurements in a low-cost and noninvasive way. The goal is to improve patient monitoring at home to ensure rapid intervention in cases of worsening conditions, either with timely hospitalizations or adjustments to a patient's usual treatment. Volum is a small, wearable, wireless, lightweight, low-power clinical pilot prototype that takes measurements through four electrodes and sends the data via Bluetooth to an Android device.
A Plethysmography Capacitive Sensor for Real-Time Monitoring of Volume Changes in Acute Heart Failure
(Institute of Electrical and Electronics Engineers, 2021-06-23) Rando, Enrique; Pérez García, Pablo; Scagliusi, Santiago F.; Medrano Ortega, Francisco Javier; Huertas Sánchez, Gloria; Yúfera García, Alberto; Universidad de Sevilla. Departamento de Tecnología Electrónica; Universidad de Sevilla. Departamento de Medicina; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Instituto de Salud Carlos III
A small, wearable, low-weight, and low-power-consumption device for plethysmography capacitive sensing is proposed herein. The device allows carrying out real-time monitoring of leg volume changes in patients suffering from heart failure (HF) conditions. The dynamic of fluid overload in patients with acute HF serves as a prognosis marker for this type of severe disease and, consequently, these patients can benefit from a wearable monitoring system to measure their body volume evolution during and after hospitalization. Our approach is based on contactless capacitive wearable structures implemented by two different sensor realizations located in the ankle: 180°-parallel capacitor plates (two modes of operations are compared, with the patient's body connected to ground and to the average voltage between plates) and planar-parallel capacitor plates whose overlapped surface varies with the volume of the patient's leg. Both realizations exhibit good sensitivity to leg volume changes. The acquisition of capacitance values is performed via a simple circuit that achieves notable performance in simulated volume analysis. A preliminary pilot clinical prototype is described as well.
A Multilevel Bottom-Up Optimization Methodology for the Automated Synthesis of RF Systems
(IEEE. Institute of Electrical and Electronics Engineers, 2019-01-01) Passos, Fabio; Roca, Elisenda; Sieiro, Javier; Fiorelli, Rafaella; Castro López, Rafael; López Villegas, José María; Fernández Fernández, Francisco Vidal; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo
In recent years there has been a growing interest in electronic design automation methodologies for the optimization- based design of radiofrequency circuits and systems. While for simple circuits several successful methodologies have been proposed, these very same methodologies exhibit significant deficiencies when the complexity of the circuit is increased. The majority of the published methodologies that can tackle radiofrequency systems are either based on high-level system specification tools or use models to estimate the system performances. Hence, such approaches do not usually provide the desired accuracy for RF systems. In this work, a methodology based on hierarchical multilevel bottom-up design approaches is presented, where multi-objective optimization algorithms are used to design an entire radiofrequency system from the passive component level up to the system level. Furthermore, each level of the hierarchy is simulated with the highest accuracy possible: electromagnetic simulation accuracy at device-level and electrical simulations at circuit/system-level.
The role of particle-electrode wall interactions in mobility of active Janus particles driven by electric fields
(Elsevier, 2025-06-15) M.Boymelgreen, A.; Kunti, G.; García Sánchez, Pablo; Ramos Reyes, Antonio; Yossifon, G.; Miloh, T.; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Ministerio de Ciencia e Innovación (MICIN). España
Hypothesis The interaction of active particles with walls can explain discrepancies between experiments and theory derived for particles in the bulk. For an electric field driven metallodielectric Janus particle (JP) adjacent to an electrode, interaction between the asymmetric particle and the partially screened electrode yields a net electrostatic force – termed self-dielectrophoresis (sDEP) - that competes with induced-charge electrophoresis (ICEP) to reverse particle direction. Experiments The potential contribution of hydrodynamic flow to the reversal is evaluated by visualizing flow around a translating particle via micro-particle image velocimetry and chemically suppressing ICEP with poly(l-lysine)-g-poly(ethylene glycol) (PLL-PEG). Mobility of Polystyrene-Gold JPs is measured in KCl electrolytes of varying concentration and with a capacitive SiO2 coating at the metallic JP surface or electrode. Results are compared with theory and numerical simulations accounting for electrode screening. Findings PLL-PEG predominantly suppresses low-frequency mobility where propulsive electro-hydrodynamic jetting is observed; supporting the hypothesis of an electrostatic driving force at high frequencies. Simulations and theory show the magnitude, direction and frequency dispersion of JP mobility are obtained by superposition of ICEP and sDEP using the JP height and capacitance as fitting parameters. Wall proximity enhances ICEP and sDEP and manifests a secondary ICEP charge relaxation time dominating in the contact limit.
Synthesis of mm-Wave Wideband Receivers in 28-nm CMOS Technology for Automotive Radar Applications
(IEEE, 2020-03-26) Moreira de Passos, Fabio; Chanca, Miguel; Roca, Elisenda; Castro-López, Rafael; Fernández Fernández, Francisco Vidal; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo
A new strategy for millimeter-wave (mm-Wave) circuit and system synthesis, where the accuracy of electromagnetic simulations can be achieved in optimization-based design methodologies without sacrificing efficiency, is presented and tested within a real industrial project. This is done by properly partitioning the system, generating libraries of passive devices which are electromagnetically simulated prior to any circuit optimization, generating performance tradeoffs at different hierarchical levels with multiobjective optimization algorithms and hierarchically composing lower level sub-blocks. With this proposed solution, an entire mm-Wave system, from the passive component level up to the system level, has been designed and compared with the results obtained from a conventional design approach, demonstrating the outstanding capabilities of the methodology.
Continuous Focusing of Particles by AC-Electroosmosis and Induced Dipole Interactions
(ACS Publications, 2024) Wiegerinck, Harm T. M.; Wood, Jeffery A.; Eijkel, Jan C.T.; Lammertink, Rob G. H.; Frankel, Itzchak; Ramos Reyes, Antonio; Universidad de Sevilla. Departamento de Electrónica y Electromagnetismo; Dutch Research Council (NWO); Universidad de Sevilla. FQM253: Electrohidrodinámica y Medios granulares cohesivos
Continuous particle focusing by using microfluidics is an effective method for separating particles, cells, or droplets for analytical purposes. Previously, it was shown that an alternating current across rectangular microchannels with slightly deformed side walls results in vortex flow patterns caused by alternating current electroosmosis (AC-EOF) and could lead to particle focusing. In this work, we explore this mechanism by experimentally studying the particle focusing behavior for various fluid flow velocities through a microchannel. Since it is unlikely that the particles are kept in their focused position solely by convection, a theoretical force balance between the hydrodynamic and the induced dipole force was determined. In our experiments, it was found that there is no substantial effect of the pressure-driven fluid velocity on the particle focusing velocity within the studied range. From the theoretical force balance calculations, it was determined that while the addition of the induced dipole force can still not completely describe the experimentally observed particle focusing, the induced dipole can be strong enough to overcome the hydrodynamic force. Finally, it is hypothesized that under specific circumstances, including a repulsive electrostatic force between a particle and electrode wall can complete the theoretical particle focusing force balance. Alternative phenomena that could also play a role in particle focusing are proposed.

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