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Amirhossein Hajiaghajani

Bio: Amirhossein Hajiaghajani is an academic researcher from University of California, Irvine. The author has contributed to research in topics: Electromagnetic coil & Radio frequency. The author has an hindex of 6, co-authored 14 publications receiving 84 citations. Previous affiliations of Amirhossein Hajiaghajani include Iran University of Science and Technology.

Papers
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11 Nov 2021
TL;DR: In this paper, textile-integrated metamaterials are used to drive long-distance near-field communication (NFC)-based magneto-inductive waves along and between multiple objects.
Abstract: Wearable and implantable sensors can be linked together to create multi-node wireless networks that could be of use in the development of advanced healthcare monitoring technologies. Such body area networks require secure, seamless and versatile communication links that can operate across the complex human body, but they typically suffer from short ranges, low power or the need for direct-connection terminals. Here we show that textile-integrated metamaterials can be used to drive long-distance near-field communication (NFC)-based magneto-inductive waves along and between multiple objects. The metamaterials are built from arrays of discrete, anisotropic magneto-inductive elements, creating a mechanically flexible system capable of battery-free communication among NFC-enabled devices that are placed anywhere close to the network. Our approach offers a secure and on-demand body area network that has the potential for straightforward expansion and can span across different pieces of clothing, objects and people. Textile-integrated metamaterials can be used to drive long-distance near-field-communication-based magneto-inductive waves along and between multiple objects, creating a secure and on-demand body area network.

37 citations

Journal ArticleDOI
TL;DR: In this article, the authors exploit the premises of exceptional points of degeneracy induced in linear time-periodic (LTP) systems to achieve extremely sensitive biosensors, where the EPD is formed in a single LC resonator where the total capacitance is comprised of a time-varying capacitor in parallel to a biosensing capacitor.
Abstract: We exploit the premises of exceptional points of degeneracy (EPDs) induced in linear time-periodic (LTP) systems to achieve extremely sensitive biosensors. The EPD is formed in a single LC resonator where the total capacitance is comprised of a time-varying capacitor in parallel to a biosensing capacitor. We use the time-periodic variation of a system parameter (e.g., capacitance) to achieve a second order EPD aiming at improving the sensitivity of liquid based radio frequency biosensors, leading to an intrinsic ultra sensitivity. We show the emergence of EPDs in such a system and the ultra sensitivity of the degenerate resonance frequency to perturbations compared to conventional RF sensors. Moreover, we investigate the capacitance and conductance variations of an interdigitated biosensing capacitor to the changes in the concentration of a biological material under test (MUT), leading to subsequent large changes in the resonance frequency of the LTP-LC resonator. A comparison with a standard LC resonator demonstrates the ultra-high sensitivity of the proposed LTP-LC based biosensor. In addition, we show the scalability of the biosensor sensitivity across different frequency ranges.

20 citations

Journal ArticleDOI
TL;DR: In this paper, a resonant wireless power transfer system is incorporated into an array of planar coils to generate spatio-temporal patterns of magnetic fields on an untethered swimming microrobot.
Abstract: Common digestive and lung disorders such as stomach problems and pleural emission pose serious difficulties for patients who undergo open surgeries wherein a wirelessly powered swimming microrobot has the potential for minimally invasive missions from diagnosis to drug delivery and surgery. However, remote steering toward an arbitrary destination is yet a challenge to existing microrobots. Here, a resonant wireless power transfer system is incorporated into an array of planar coils to generate spatio-temporal patterns of magnetic fields on an untethered swimming microrobot. As shown, this generates an effective Lorentz force on the microrobot's power receptor coil. Automated switching of the array current creates a traveling magnetic pattern that enables smooth microrobot steering and controls its velocity. This eliminates the need for embedded magnets and shielding materials that suffer from nonlinear characteristics. The microrobot's function is validated by an in vitro experiment that mimics the anatomy of the stomach filled with fluid at a centimeter range underneath the skin. Our microrobot with a mass of 7 g is able to reach the velocity of 0.45 mm/s in a controlled direction by applying a small peak magnetic field of 2.15 mT at 96 kHz. The propelling force is proportional to the square of the total magnetic field's intensity and can be enormously increased depending on the application. Compared to microrobots with similar dimensions, this method results in a 50-fold increased ratio of propelling force to applied magnetic energy, which is suitable for carrying heavier payloads to farther locations.

19 citations

Journal ArticleDOI
TL;DR: A low intensity magnetic field is designed which avoids potential side effects on blood cells while steers particles with high targeting rate in muscular arteries, in where the vessel diameter and blood flow are much challengingly higher than brain capillaries.

16 citations

Journal ArticleDOI
TL;DR: In this paper, arbitrary 2-dimensional spatial patterns of magnetic fields from DC to megahertz are represented in terms of spatial Fourier spectra with sinusoidal eigenfunctions and it is shown that the desired pattern was synthesized by simultaneous use of coil sets.
Abstract: In cancer therapy, magnetic drug targeting is considered as an effective treatment to reduce chemotherapy's side effects. The accurate design and shaping of magnetic fields are crucial for healthy cells to be immune from chemotherapeutics. In this paper, arbitrary 2-dimensional spatial patterns of magnetic fields from DC to megahertz are represented in terms of spatial Fourier spectra with sinusoidal eigenfunctions. Realization of each spatial frequency was investigated by a set of elliptical coils. Therefore, it is shown that the desired pattern was synthesized by simultaneous use of coil sets. Currents running on each set were obtained via fast and straightforward analytical Fourier series calculation. Experimentally scanned sample patterns were in close agreement with full wave analysis. Discussions include the evaluation of the Fourier series approximation error and cross-polarization of produced magnetic fields. It was observed that by employing the controlled magnetic field produced by the proposed setup, we were able to steer therapeutic particles toward the right or left half-spheres of the breast, with an efficiency of 90%. Such a pattern synthesizer may be employed in numerous human arteries as well as other bioelectromagnetic patterning applications, e.g., wireless power transfer, magnetic innervation, and tomography. Bioelectromagnetics. 39:325-338, 2018. © 2018 Wiley Periodicals, Inc.

13 citations


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01 Jan 2016
TL;DR: The introduction to electrodynamics is universally compatible with any devices to read and is available in the book collection an online access to it is set as public so you can get it instantly.
Abstract: Thank you for downloading introduction to electrodynamics. Maybe you have knowledge that, people have look numerous times for their chosen books like this introduction to electrodynamics, but end up in infectious downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they juggled with some malicious bugs inside their computer. introduction to electrodynamics is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers spans in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the introduction to electrodynamics is universally compatible with any devices to read.

1,025 citations

Journal ArticleDOI
TL;DR: This review presents an overview of wearable pressure sensors for human pulse wave monitoring, with a focus on the transduction mechanism, microengineering structures, and related applications in pulse wave Monitoring and cardiovascular condition assessment.
Abstract: Cardiovascular diseases remain the leading cause of death worldwide. The rapid development of flexible sensing technologies and wearable pressure sensors have attracted keen research interest and have been widely used for long‐term and real‐time cardiovascular status monitoring. Owing to compelling characteristics, including light weight, wearing comfort, and high sensitivity to pulse pressures, physiological pulse waveforms can be precisely and continuously monitored by flexible pressure sensors for wearable health monitoring. Herein, an overview of wearable pressure sensors for human pulse wave monitoring is presented, with a focus on the transduction mechanism, microengineering structures, and related applications in pulse wave monitoring and cardiovascular condition assessment. The conceptualizations and methods for the acquisition of physiological and pathological information related to the cardiovascular system are outlined. The biomechanics of arterial pulse waves and the working mechanism of various wearable pressure sensors, including triboelectric, piezoelectric, magnetoelastic, piezoresistive, capacitive, and optical sensors, are also subject to systematic debate. Exemple applications of pulse wave measurement based on microengineering structured devices are then summarized. Finally, a discussion of the opportunities and challenges that wearable pressure sensors face, as well as their potential as a wearable intelligent system for personalized healthcare is given in conclusion.

159 citations

Journal ArticleDOI
TL;DR: The progresses made in magnetic drug targeting are reviewed, the systems already developed or proposed are summarized, and they are categorized into two groups: static field magnet systems and varying field magnet Systems.

157 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of magnetic fields and ultrasound on cancer cells and their application for cancer treatment in the presence of drugs or DDS are discussed, with or without DDS, involving the use of light, heat, magnetic field, electrical field and ultrasound.

83 citations

Journal ArticleDOI
TL;DR: In this article , the recent advances of textile TENGs with 3D fabric structures are comprehensively summarized and systematically analyzed in order to clarify their superiorities over 1D fiber and 2D fabrics structures in terms of power output and pressure sensing.
Abstract: The seamless integration of emerging triboelectric nanogenerator (TENG) technology with traditional wearable textile materials has given birth to the next‐generation smart textiles, i.e., textile TENGs, which will play a vital role in the era of Internet of Things and artificial intelligences. However, low output power and inferior sensing ability have largely limited the development of textile TENGs. Among various approaches to improve the output and sensing performance, such as material modification, structural design, and environmental management, a 3D fabric structural scheme is a facile, efficient, controllable, and scalable strategy to increase the effective contact area for contact electrification of textile TENGs without cumbersome material processing and service area restrictions. Herein, the recent advances of the current reported textile TENGs with 3D fabric structures are comprehensively summarized and systematically analyzed in order to clarify their superiorities over 1D fiber and 2D fabric structures in terms of power output and pressure sensing. The forward‐looking integration abilities of the 3D fabrics are also discussed at the end. It is believed that the overview and analysis of textile TENGs with distinctive 3D fabric structures will contribute to the development and realization of high‐power output micro/nanowearable power sources and high‐quality self‐powered wearable sensors.

81 citations