Antoni Ivorra

Antoni Ivorra
University Pompeu Fabra | UPF · Department of Information and Communication Technologies (DTIC)

PhD

About

133
Publications
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Publications

Publications (133)
Article
Full-text available
Pulsed Field Ablation (PFA) has been developed over the last years as a novel electrical ablation technique for treating cardiac arrhythmias. It is based on irreversible electroporation which is a non-thermal phenomenon innocuous to the extracellular matrix and, because of that, PFA is considered to be safer than the reference technique, Radiofrequ...
Article
Full-text available
Objective: To develop and in vivo demonstrate threadlike wireless implantable neuromuscular microstimulators that are digitally addressable. Approach: These devices perform, through its two electrodes, electronic rectification of innocuous high frequency current bursts delivered by volume conduction via epidermal textile electrodes. By avoiding...
Article
Objective: Wireless power transfer (WPT) is used as an alternative to batteries to accomplish miniaturization in electronic medical implants. However, established WPT methods require bulky parts within the implant or cumbersome external systems, hindering minimally invasive deployments and the development of networks of implants. As an alternative...
Article
Full-text available
Background Implantable neuroprostheses consisting of a central electronic unit wired to electrodes benefit thousands of patients worldwide. However, they present limitations that restrict their use. Those limitations, which are more adverse in motor neuroprostheses, mostly arise from their bulkiness and the need to perform complex surgical implanta...
Article
Full-text available
Brain electrical stimulation techniques take advantage of the intrinsic plasticity of the nervous system, opening a wide range of therapeutic applications. Vagus nerve stimulation (VNS) is an approved adjuvant for drug-resistant epilepsy and depression. Its non-invasive form, auricular transcutaneous VNS (atVNS), is under investigation for applicat...
Preprint
Objective To develop and in vivo demonstrate threadlike wireless implantable neuromuscular microstimulators that are digitally addressable. Approach These devices perform, through its two electrodes, electronic rectification of innocuous high frequency current bursts delivered by volume conduction via epidermal textile electrodes. By avoiding the...
Preprint
Background Implantable neuroprostheses consisting of a central electronic unit wired to electrodes benefit thousands of patients worldwide. However, they present limitations that restrict their use. Those limitations, which are more adverse in motor neuroprostheses, mostly arise from their bulkiness and the need to perform complex surgical implanta...
Research Proposal
Full-text available
Neural interfaces are well known to the biomedical community and, increasingly, to the general public. In comparison with non-invasive technologies, implantable approaches are usually advantageous in terms of spatial selectivity, quality of signal (i.e., higher signal-to-noise ratio), and usability. However, there are some important risks associate...
Preprint
Background: Brain electrical stimulation techniques take advantage of the intrinsic plasticity of the nervous system, opening a wide range of therapeutic applications. Vagus nerve stimulation (VNS) is an approved adjuvant for drug-resistant epilepsy and depression. Its non-invasive form, auricular transcutaneous VNS (atVNS), is under investigation...
Article
Objective: Irreversible electroporation (IRE) is a non thermal tissue ablation therapy which is induced by applying high voltage waveforms across electrode pairs. When multiple electrode pairs are sequentially used, the treatment volume (TV) is typically computed as the geometric union of the TVs of individual pairs. However, this method neglects...
Article
Full-text available
The use of networks of wireless active implantable medical devices (AIMDs) could revolutionize the way that numerous severe illnesses are treated. However, the development of sub-mm AIMDs is hindered by the bulkiness and the transmission range that consolidated wireless power transfer (WPT) methods exhibit. The aim of this work is to numerically st...
Article
This study compared monophasic 100-μs pulses with high-frequency electroporation (HF-EP) bursts using an in vivo animal model. Myocardial damage was evaluated by histologic analysis. Compared with 10 monophasic pulses, 20 bursts of HF-EP at 100 and 150 kHz were associated with less damage. However, when the number of HF-EP bursts was increased to 6...
Preprint
Full-text available
Aiming at miniaturization, wireless power transfer (WPT) is frequently used in biomedical electronic implants as an alternative to batteries. However, WPT methods in use still require integrating bulky parts within the receiver, thus hindering the development of devices implantable by minimally invasive procedures, particularly when powers above 1...
Conference Paper
Wireless active implantable medical devices (AIMDs) can be an alternative for overcoming the drawbacks faced with superficial and percutaneous technologies. However, current AIMDs require bulky and rigid components for powering, hampering their miniaturization. AIMDs based on power transfer by volume conduction do not need these voluminous parts, a...
Article
Full-text available
Background and objectives Electroporation is the phenomenon by which cell membrane permeability to ions and macromolecules is increased when the cell is briefly exposed to high electric fields. In electroporation-based treatments, such exposure is typically performed by delivering high voltage pulses across needle electrodes in tissue. For a given...
Article
Full-text available
Objective: It is known that multi-site interleaved stimulation generates less fatigue compared to single-site synchronous stimulation. However, in the limited number of studies in which intramuscular electrodes were used, the fatigue reduction associated with interleaved stimulation could not consistently be achieved. We hypothesize that this coul...
Article
Pulsed radiofrequency (PRF) treatments for chronic pain consist in the delivery of a train of sinusoidal electric bursts to the targeted nerve. Despite numerous clinical evidence of its efficiency, the mechanism of action of PRF remains unclear. Since most of the reported biological effects of PRF can be initiated by a calcium influx into the neuro...
Article
Full-text available
Sensing implants that can be deployed by catheterization or by injection are preferable over implants requiring invasive surgery. However, present powering methods for active implants and present interrogation methods for passive implants require bulky parts within the implants that hinder the development of such minimally invasive devices. Here we...
Article
Optimization of protocols is required for each specific type of biomass processed by electroporation of the cell membrane with high voltage pulsed electric fields (PEF). Such optimization requires convenient and adaptable laboratory systems, which will enable determination of both electrical and mechanical parameters for successful electroporation...
Article
Full-text available
Galvanic coupling, or more precisely volume conduction, has been recently studied by different research groups as a method for intrabody communications. However, only in a very few occasions its use for powering implants has been proposed and proper analyses of such capability are still lacking. We present the development and the in vitro validatio...
Article
Full-text available
High-frequency irreversible electroporation (H-FIRE) has emerged as an alternative to conventional irreversible electroporation (IRE) to overcome the issues associated with neuromuscular electrical stimulation that appear in IRE treatments. In H-FIRE, the monopolar pulses typically used in IRE are replaced with bursts of short bipolar pulses. Curre...
Article
Electrolytic Electroporation (E2) is the combination of reversible electroporation and electrolysis. It has been proposed as a novel treatment option to ablate tissue percutaneously. The present in vitro study in cells in suspension was performed to investigate the underlying mechanisms of action of E2. Different types of experiments were performed...
Article
Full-text available
Background: Vagus nerve stimulation (VNS) using non-invasive approaches have attracted great attention due to their anti-epileptic, anti-depressive and pro-cognitive effects. It has been proposed that auricular transcutaneous VNS (atVNS) could benefit intellectual disability disorders, but preclinical data supporting this idea is limited. Objecti...
Method
Full-text available
EView is an on-line platform for 3D electric field simulation in electroporation-based treatments using needle-shaped electrodes. EView provides an easy way to obtain approximate estimations of the electric field distribution for arbitrary electrode positions and orientations. EView results can be overlaid on medical images. EView has been develope...
Article
Full-text available
Background: The combination of electroporation with electrolysis (E2) has previously been introduced as a novel tissue ablation technique. E2 allows the utilization of a wide parameter range and may therefore be a suitable technology for development of tissue-specific application protocols. Previous studies have implied that it is possible to achi...
Chapter
In the past it has been proposed to use implanted electromyography (EMG) sensors for myoelectric control. In contrast to surface systems, these implanted sensors provide signals with low cross-talk. To achieve this, miniature implantable devices that acquire and transmit real-time EMG signals are necessary. We have recently in vivo demonstrated ele...
Conference Paper
Full-text available
While galvanic coupling for intrabody communications has been proposed lately by different research groups, its use for powering active implantable medical devices remains almost non-existent. Here it is presented a simple analytical model able to estimate the attainable power by galvanic coupling based on the delivery of high frequency (>1 MHz) el...
Article
Full-text available
Bioimpedance spectroscopy measurements can be used for tissue characterization. These measurements can be performed in soft tissues by direct contact of a non-invasive probe consisting of two or four electrodes. The amount of force applied by users can be quite different, and the measurements can vary as a result. To compensate for this, we have bu...
Conference Paper
This paper presents preliminary results on the effect of contact pressure on bioimpedance measurements in an excised section of human colon tissue. The impedance measurements were performed with a small diameter probe suitable for in-vivo use, which is capable of measuring contact force. Force measurements are performed by fiber optic sensor which...
Article
Introduction: Cardiac ablation is an established treatment modality for the management of patients with cardiac arrhythmias. Current approaches to cardiac ablation employ thermal based energy to achieve lesions (damage) within the heart. There are many shortcomings and limitations of thermal based approaches. Electroporation (DC energy) is a non-th...
Article
Background: Intraluminal electrical impedance is a well-known diagnostic tool used to study bolus movement in the human esophagus. However, it is use in the human colon it is hindered by the fact that the content cannot be controlled and may include liquid, gas, solid, or a mixture of these at any one time. This article investigates the use of com...
Article
Electroporation based treatments typically consist in applying high voltage dc pulses. As an undesired side effect, these dc pulses cause electrical stimulation of excitable tissues such as motor nerves. In the present in vivo study, it was explored the use of bursts of sinusoidal voltage in the frequency range from 50 kHz to 2 MHz to induce irreve...
Article
Full-text available
Background Spread hepatic tumours are not suitable for treatment either by surgery or conventional ablation methods. The aim of this study was to evaluate feasibility and safety of selectively increasing the healthy hepatic conductivity by the hypersaline infusion (HI) through the portal vein. We hypothesize this will allow simultaneous safe treatm...
Chapter
To overcome the miniaturization bottleneck imposed by existing power generation/transfer technologies for implantable stimulators, we have proposed a heterodox electrical stimulation method based on local rectification of high frequency (≥1 MHz) current bursts delivered through superficial electrodes. We have reported 2 mm thick addressable injecta...
Article
Electroporation based treatments consist in applying one or multiple high voltage pulses to the tissues to be treated. As an undesired side effect, these pulses cause electrical stimulation of excitable tissues such as nerves and muscles. This increases the complexity of the treatments and may pose a risk to the patient. To minimize electrical stim...
Chapter
Electroporation causes an immediate increase in cell membrane permeability that results in membrane conductivity increase, which has an effect in the measured impedance of the cell suspension or the tissue. Therefore, impedance measurements offer the possibility to perform real-time assessment of the electroporation phenomenon in a minimally invasi...
Article
Metastases in the liver frequently grow as scattered tumor nodules which neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation which may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requir...
Article
Background: The thermal and electrical effects of pulsed radiofrequency (PRF) for pain relief can be controlled by modifying the characteristics of the RF pulses applied. Our goal was to evaluate the influence of such modifications on the thermal and electric performance in tissue. Methods: A computational model was developed to compare the tempera...
Article
Full-text available
Irreversible electroporation (IRE) has recently gained in popularity as an ablative technique, however little is known about its oncological long-term outcomes. To determine the long-time survival of animals treated with a high dose of IRE and which histological changes it induces in tumoral tissue, IRE ablation was performed in forty-six athymic-n...
Article
Irreversible electroporation is a novel tissue ablation technique which entails delivering intense electrical pulses to target tissue, hence producing fatal defects in the cell membrane. The present study numerically analyzes the potential impact of liver blood vessels on ablation by irreversible electroporation because of their influence on the el...
Conference Paper
We present a mobile and low cost 4-terminal bioimpedance measurement system, consisting of a Red Pitaya board and a front-end, for understanding gastrointestinal physiology and exploring new applications for bioimpedance spectroscopy in gastroenterology. System accuracy was evaluated with a set of impedance standards from 1 ohm to 1 Mohm and an equ...
Article
Existing implantable stimulators use powering approaches that result in stiff and bulky systems or result in systems incapable of producing the current magnitudes required for neuromuscular stimulation. This hampers their use in neuroprostheses for paralysis. We previously demonstrated an electrical stimulation method based on electronic rectificat...
Article
Full-text available
It is widely accepted that electroporation occurs when the cell transmembrane voltage induced by an external applied electric field reaches a threshold. Under this assumption, in order to trigger electroporation in a spherical cell, Schwan’s equation leads to an inversely proportional relationship between the cell radius and the minimum magnitude o...
Article
Full-text available
Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around...
Article
Ablative techniques based on irreversible electroporation (IRE) have emerged as an effective cancer therapy. In these treatments electrical pulses are delivered in order to induce irrecoverable damage to the cell membranes, thus, causing cell death. An interesting feature of electroporation treatments is the capability to predict shape and extensio...
Chapter
Electroporation causes an immediate increase in cell membrane permeability that results in membrane conductivity increase, which has an effect in the measured impedance of the cell suspension or the tissue. Therefore, impedance measurements offer the possibility to perform real-time assessment of the electroporation phenomenon in a minimally invasi...
Article
Full-text available
Objective: It is possible to develop implantable microstimulators whose actuation principle is based on rectification of high-frequency (HF) current bursts supplied through skin electrodes. This has been demonstrated previously by means of devices consisting of a single diode. However, previous single diode devices caused dc currents which made th...
Conference Paper
Full-text available
Electroporation can be used in living tissues in order to enhance the penetration of drugs or DNA plasmids or to destroy undesirable cells and it is typically performed by applying pulsed high voltages across needle electrodes. When used for ablation, it is often claimed that, in contrast with thermal ablation techniques, electroporation is not sig...
Article
Full-text available
Electrical stimulation is used in order to restore nerve mediated functions in patients with neurological disorders, but its applicability is constrained by the invasiveness of the systems required to perform it. As an alternative to implantable systems consisting of central stimulation units wired to the stimulation electrodes, networks of wireles...
Conference Paper
Full-text available
Functional Electrical Stimulation (FES) has been used in order to restore muscle functions in patients suffering from neurological disorders. This therapeutic approach benefits from technological improvements that yield miniaturization. We previously have proposed and demonstrated an innovative electrical stimulation method in which wireless implan...
Article
Delivery of the so-called Tumor Treatment Fields (TTFields) has been proposed as a cancer therapy. These are low magnitude alternating electric fields at frequencies from 100 to 300kHz which are applied continuously in a non-invasive manner. Electric field delivery may produce an increase in temperature which cannot be neglected. We hypothesized th...
Article
Spread tumors in liver are not suitable to be treated with local treatments, such as conventional surgery or radiofrequency ablation, thus entailing a poor prognosis. Electroporation- based therapies imply the delivery of pulsed high electric fields and currently are performed in a local fashion using needle or plate electrodes. Here, however, it i...
Article
Electroporation is the phenomenon in which cell membrane permeability is increased by exposing the cell to high intensity electric fields. In living tissues, such permeabilization boost can be used in order to enhance the penetration of drugs or DNA plasmids or to destroy undesirable cells and it is typically performed by applying pulsed high volta...
Article
Electroporation is an effective technique based on applying an electric field to cells, commonly used to increase the effectivity of drug and gene delivery. When the applied electric field is strong enough, it can be used for selective cell death with promising results in cancer treatment. This paper proposes the development of a modular multilevel...
Conference Paper
Functional Electrical Stimulation (FES) has been explored in order to restore the capabilities of the nervous system in patients that suffer from paralysis. This area of research and of clinical practice greatly benefits from any technological improvement yielding miniaturization. In this regard, we recently proposed and demonstrated an innovative...
Conference Paper
Full-text available
Electrical stimulation has been explored to restore the capabilities of the nervous system in paralysis patients. This area of research and of clinical practice, known as Functional Electrical Stimulation, would greatly benefit from further miniaturization of implantable stimulators. To that end, we recently proposed and demonstrated an innovative...
Conference Paper
Full-text available
Miniaturization of implantable medical electronic devices is currently compromised by the available means for powering them. Most common energy supply techniques for implants – batteries and inductive links – comprise bulky parts which, in most cases, are larger than the circuitry they feed. For overcoming such miniaturization bottleneck in the cas...
Article
Pulsed Electric Field technologies have captured the attention of researchers on food pasteurization because of their non-thermal inactivation mechanism, which results in fresh-like products. Nevertheless, high voltage pulsing required by these technologies implies complex and costly generators. Here, as an alternative, it is proposed a method, par...
Article
Applications of cell electropermeabilization are rapidly growing but basic concepts are still unclear. In particular, the impact of electric pulses repetition rate in the efficiency of permeabilisation has not yet been understood. The impact of electric pulses repetition rate in the efficiency of permeabilisation was analysed in experiments perform...
Conference Paper
Full-text available
Miniaturization of implantable medical electronic devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants – batteries and inductive couplers – comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. For overcoming such miniatu...