Denys Nikolayev

Denys Nikolayev
French National Centre for Scientific Research | CNRS · IETR (UMR 6164) Rennes

CNRS Researcher

About

64
Publications
10,078
Reads
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350
Citations
Additional affiliations
February 2020 - present
French National Centre for Scientific Research
Position
  • Research Officer
March 2019 - February 2020
École Polytechnique Fédérale de Lausanne
Position
  • PostDoc Position
January 2018 - February 2019
Ghent University
Position
  • PostDoc Position
Education
May 2014 - September 2017
Université de Rennes 1
Field of study
  • Electronics
September 2012 - September 2017
University of West Bohemia
Field of study
  • Electrical Engineering
September 2003 - November 2008
Lviv Polytechnic National University
Field of study
  • Telecommunication Technologies and Equipment

Publications

Publications (64)
Article
Full-text available
Progress in implantable and ingestible wireless biotelemetry requires versatile and efficient antennas to communicate reliably from a body. We propose an ultra-miniature 434 MHz antenna immune to impedance detuning caused by varying electromagnetic properties of the surrounding biological environment. It is designed for a standard input impedance o...
Article
Full-text available
Autonomous wireless body-implanted devices for biotelemetry, telemedicine, and neural interfacing constitute an emerging technology providing powerful capabilities for medicine and clinical research. We study the through-tissue electromagnetic propagation mechanisms, derive the optimal frequency range, and obtain the maximum achievable efficiency f...
Article
Background and Objective: In-body biotelemetry devices enable wireless monitoring of a wide range of physiological parameters. These devices rely on antennas to interface with external receivers, yet existing systems suffer from impedance detuning caused by the substantial differences in electromagnetic properties among various tissues. In this pap...
Article
Full-text available
Autonomous implantable bioelectronics requires efficient radiating structures for data transfer and wireless powering. The radiation of body-implanted capsules is investigated to obtain the explicit radiation optima for E- and B-coupled sources of arbitrary dimensions and properties. The analysis uses the conservation-of-energy formulation within d...
Article
Full-text available
Wireless in-body bioelectronics offer powerful biosensing and therapeutic capabilities. Efficient and robust in-body antenna designs are required to ensure a reliable through-body link, increase data rates, and reduce power budgets. This study proposes and demonstrates a pattern- and frequency-reconfigurable capsule-conformal antenna array that res...
Preprint
Full-text available
Several frequency-dependent mechanisms restrict the maximum achievable efficiency for wireless powering implantable bioelectric devices. Similarly, many mathematical formulations have been proposed to evaluate the effect of these mechanisms as well as predict this maximum efficiency and the corresponding optimum frequency. However, most of these me...
Preprint
Full-text available
Objective: Numerical modeling of electric fields induced by transcranial alternating current stimulation (tACS) is currently a part of the standard procedure to predict and understand neural response. Quasi-static approximation for electric field calculations is generally applied to reduce the computational cost. This study aims to analyze and quan...
Article
Full-text available
The purpose of this work is to evaluate local power and electric field distributions inside high-resolution 3D anatomical CAD models of cutaneous appendages at 60 GHz upcoming for 5G/6G. The microscale resolution models of cutaneous nerves, lymphatics, pilosebaceous unit, microvasculature, eccrine sweat glands, Meissner corpuscle and Pacinian corpu...
Article
Full-text available
The aim of this study was to investigate quantitatively local sub-cellular power deposition at frequencies upcoming for wireless power transfer (WPT) and millimeter-wave (mmWave) technologies. The study was performed on a realistic two-dimensional keratinocyte cell model, designed based on electron microscopy images and experimental data on surface...
Conference Paper
Wireless Power Transfer (WPT) techniques allow significant miniaturisation of implanted medical devices. However, the electromagnetic exposure of the body tissues must be accurately accessed to ensure safe operation. This study, therefore, analyses the exposure induced by the magnetic- and electric-type antenna transmitters over the frequency range...
Article
Objective: Cellular sensitivity to heat is highly variable depending on the cell line. The aim of this paper is to assess the cellular sensitivity of the A375 melanoma cell line to continuous (CW) millimeter-waves (MMW) induced heating at 58.4 GHz, between 37 C and 47 C C to get a deeper insight into optimization of thermal treatment of superficia...
Conference Paper
Full-text available
The efficiency of an on-body wireless power transfer system for implant powering is defined by how the electromagnetic energy interacts with the lossy, heterogeneous, and dispersive body tissues. The objective of this study is to discuss the methodology and evaluate the theoretical bounds for the frequency-dependent electromagnetic energy transfer...
Article
Full-text available
With the fast development of 5th generation (5G) mobile networks and prominence of the personal area networks and human-centered communications, people of all ages are increasingly exposed in the upper part of the microwave spectrum. In some exposure scenarios, presence of a textile between the radiating source and skin can affect the power absorpt...
Conference Paper
Full-text available
Fundamental limits for implanted antennas should be able to evaluate the bounds on losses with the knowledge of physical limitations from antenna and tissue parameters. In this work, rules of thumb to assess losses of deeply implanted antennas are presented toward improving the radiation efficiency. By means of rigorous and approximate approaches,...
Article
Automated systems based on wearable sensors for livestock monitoring are becoming increasingly popular. Specifically, wireless in-body sensors could yield relevant data such as ruminal temperature. The collection of such data requires an accurate characterization of the in-to-out body wireless channel between the in-body sensor and the gateway. The...
Conference Paper
Full-text available
Fundamental in-body limitations on achievable radiation efficiency could provide decision-making assistance to engineers working on antennas for implantable bioelectronics. In this study, proof-of-concept conformal microstrip antennas are proposed based on these theoretical foundations. In particular, maximizing the effective aperture and loading t...
Article
Wireless technologies are essential components of wearable devices for applications ranging from connected healthcare to human-machine interfaces. Their performance, however, is hindered by the human body, which obstructs the propagation of wireless signals over a wide range of directions. Here, we demonstrate conformal propagation and near-omnidir...
Conference Paper
Full-text available
Wireless neural interfaces provide major leap capabilities for neurotechnology by removing hazardous and bulky percutaneous links. This study addresses for the first time the radio frequency (RF) electromagnetic (EM) exposure of mm-sized neural implant antennas in the frequency range from 100 MHz to 4 GHz. The results demonstrate the existence of m...
Conference Paper
Full-text available
Fundamental limits on radiation performance of implantable antennas serve as the design quality gauge, facilitate the choice of the antenna type, and provide simple design rules to maximize the radiation performance. This study obtains the limits using two formulations: 1) theoretical spherical-wave expansion using elementary magnetic and electric...
Conference Paper
Full-text available
Conformal antenna arrays are able to fit seamlessly on curved 3D-shaped surfaces, which are found ubiquitously on vehicles, aircraft, a human body, etc. In addition, conformal structures can overcome the scan loss limitations of conventional planar arrays. Yet, only a few computational analysis methods have been proposed with either performance or...
Conference Paper
Full-text available
Fundamental bounds on achievable radiation efficiency serve as the design quality gauge, facilitate the choice of the antenna type considering the available dimensions, and provide simple rules to check the feasibility of a given design. This study quantifies the effect of body-implanted capsule dimensions and materials on achievable radiation effi...
Article
Wireless implantable bioelectronics and accurate in vivo characterization of path loss require efficient and robust in-body antennas. Loading electric antennas with the effective permittivities higher than that of surrounding tissues is a promising solution. In this study, proof-of-concept conformal microstrip antennas are proposed. The antennas ar...
Article
Shallow penetration of millimeter waves (MMW) and non‐uniform illumination in in vitro experiments result in a non‐uniform distribution of the specific absorption rate (SAR). These SAR gradients trigger convective currents in liquids affecting transient and steady‐state temperature distributions. We analyzed the effect of convection on temperature...
Conference Paper
Full-text available
Miniature wireless implantable bioelectronics provide powerful capabilities for biotelemetry, therapeutics, and neural interfacing. These technologies rely on antennas to communicate with external receivers, yet existing systems suffer from poor radiation performance. We address this issue by studying the through-tissue propagation, deriving the op...
Conference Paper
This study investigates the impact of convection on temperature dynamics in a typical in vitro exposure scenario during continuous and pulsed millimetre-wave (MMW) induced heating. Results showed that the onset of convection during continuous heating i) is preceded by the appearance of a temperature peak, which occurrence in time depends on SAR (th...
Conference Paper
Full-text available
In-body bioelectronics relies on antennas to interface with external on-or off-body equipment. In this paper, we address the impedance detuning of in-body antennas caused by nondeterministic electromagnetic properties of biological tissues. The impedance robustness can be improved in two ways. First, by using wideband and multiresonance antennas wi...
Article
Background: Uniform current density electrodes can reduce the risk of electrode corrosion and tissue damage, but existing geometries do not suit thin planar leads. Objectives: This study examines current density distribution (CDD) on low-profile electrode designs and proposes an approach to obtain optimal geometries with near-uniform CDD requiring...
Article
In this Letter, for the first time, the in-to-out-body path loss between an antenna placed inside the cows’ rumen and a distant gateway was characterised at 433 MHz. Measurements were conducted on seven different fistulated cows using a signal generator and a spectrum analyser. Subsequent measurement of the antenna in free space was used to quantif...
Conference Paper
Full-text available
Emerging wireless in-body devices pave the way to many breakthroughs in healthcare and clinical research. This technology enables monitoring of physiological parameters while maintaining mobility and freedom of movement of its user. However, establishing reliable communication between an in-body device and external equipment is still a major challe...
Article
Full-text available
In-body antennas couple strongly to surrounding biological tissues thus resulting in radiation efficiencies well below 1%. Here, we quantify how the permittivity and conductivity, each individually, affect the radiation efficiency of miniature implantable and ingestible antennas. We use a generic pill-sized capsule antenna and a spherical homogeneo...
Conference Paper
Full-text available
Long-range in-body biomedical telemetry enables monitoring of physiological parameters while maintaining mobility and freedom of movement. This emerging technology creates new applications in medicine, clinical research, wellness, and defense. Current in-body biotelemetry devices operate within about a meter around a user that limits their applicab...
Article
Full-text available
In-body devices for wireless biotelemetry and neural interfacing could empower many breakthroughs in medicine and clinical research. Despite significant progress in antenna design, improving the radiation performance of miniature in-body devices remains a major challenge because, for the time being, they are able to operate at distances of only up...
Conference Paper
We propose a versatile 434 MHz in-body capsule antenna suitable for ingestible and variety of implantable applications. The low profile conformal antenna is synthesized using a hybrid analytical–numerical approach and optimized for robust operation at 434 MHz inside a 17 mm long biocompatible encapsulation (7 mm diameter). The antenna remains match...
Article
When designing a TEM transmission line cell for electromagnetic compatibility susceptibility or immunity tests, its input impedance must be properly defined in order to deliver the maximum power to the device under test. The closed-form solution, relating the cell geometry with the characteristic impedance Zc, is possible only for the simplest “can...
Chapter
Full-text available
Body-centric wireless networking and communications is an emerging 4G technology for short (1-5 m) and very short (below 1 m) range communications systems, used to connect devices worn on (or in) the body, or between two people in close proximity. It has a great potential for applications in healthcare delivery, entertainment, surveillance, and eme...
Conference Paper
We propose an approach to increase the operating range and matching stability of in-body ingestible or implantable capsule antennas. It involves using high permittivity biocompatible superstrate on a high-Q narrowband microstrip antenna. In this way, the antenna–body coupling can be significantly reduced, resulting in improved detuning immunity, in...
Book
Full-text available
The electronic implants for biomedical applications came out in mid-50s with the invention of the first pacemakers. This healthcare innovation exposed the potential and revealed the vast opportunities in the field of implantable electronic devices, enabling new ways of diagnostics and treatments maintaining the patient mobility. So, the idea of wir...
Conference Paper
This paper overviews the measurement and simulation of the electric parameters of a small stripline. The stripline was designed and built for electromagnetic compatibility (EMC) testing of small electronic devices with the accent on electromagnetic immunity (EMI) testing. The paper describes the measurement of electric field inside the stripline in...
Conference Paper
Two important parameters of triboelectric separation of plastic particles are analyzed: the distribution of their electric charges and their critical velocity (velocity, at which the trajectories of falling particles are not longer significantly influenced by the applied electric field). The analysis is performed by a combination of experimental an...
Conference Paper
Electromagnetic field distribution in a phantom is used to calculate SAR values for RF equipment compliance tests. We hypothesized that head structure could act like a dielectric resonator for some frequencies, thus affecting field estimation and measurement by procedures used today. Eigenfrequency problem for a structurally realistic 2D head phant...
Article
RF equipment compliance tests employ electromagnetic field calculation in a head phantom to derive SAR values. We hypothesized that a biological tissue in certain conditions could act like a dielectric resonator hence affecting the field estimation. To study the resonance effects in a human head, we formulated an eigenfrequency problem for a struct...
Conference Paper
Parallel plate antennas (or improved TEM-cell, strip line antenna, etc.) are used in electromagnetic compatibility for a susceptibility testing. The well-designed antenna represents transmission line with transverse electromagnetic (TEM) wave propagation and the electromagnetic field between plates is uniform. In the area with the uniform field are...
Article
Full-text available
Both ionizing and non-ionizing radiation dosimetry studies, medical imaging technologies, and image reconstruction algorithms require computational phantoms to assess health effects, to analyze efficiency and to test algorithms. The goal of this study is to overview existing models of a human body and to develop the anatomically realistic boundary...
Conference Paper
This paper presents an approach to assess exposure from mobile telecommunication systems in crowded places like trains, elevators, public gatherings etc. The results of the study testify that high concentration of wireless devices can create zones with elevated electromagnetic field intensity in certain conditions, especially when reflective surfac...

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Projects

Projects (3)
Project
https://www.mdpi.com/journal/sensors/special_issues/advanced_electromagnetic_biosensors Dear colleagues, The interest in and potential of electromagnetic technologies for sensing purposes in medical, environmental, and industrial contexts has been increasing exponentially. The benefits of electromagnetic biosensors include minimally invasive, label-free, and cost effective monitoring, probing, and treatment. For instance, wearable and implantable sensors for monitoring of vital signs and neural activity represent the key enablers towards personalized medicine and electroceuticals. Furthermore, radiofrequency and terahertz sensors are increasingly used for quality control in food industry and for the detection of environmental pollutants. The purpose of this Special Issue is to provide an update on the recent research advancements in the field of electromagnetic biosensors covering the band from low frequencies to terahertz. Original research articles and reviews are encouraged. The scope of this Special Issue include, but is not limited, to: Wearable and implantable electromagnetic sensors Antennas for in- and on-body sensors RFID sensors Wireless power transfer for autonomous sensors Bio-inspired sensors Electromagnetic characterization applied to biosensors Biocompatibility of implantable devices Nanomaterials for sensing purposes Dr. Olga Zeni Dr. Maxim Zhadobov Dr. Stefania Romeo Dr. Denys Nikolayev Guest Editors
Project
To design a robust and efficient multi-band antenna system for miniature in-body and cutaneous electronics. Ensure reliable long range communication of biotelemetry data as well as efficient wireless powering via RF.