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Giant magnetoresistance (GMR) sensors have been used due to their high sensitivity and resolution. A new calibration and localisation algorithm has been coded and implemented. In order to generate the required homogenous magnetic field, a custom 3D printed Hallbach cylinder has been simulated and characterised. The system includes sensory and electronic boards to collect the data and to transfer them to a computing server. The experimental results are displayed in a visual interface. Ferrofluid is used to model and simulate the magnetic field change of the cell. This paper demonstrates a 4×4 sensors array and provides a step towards the miniaturised on-chip magnetoresistive based cell detection and localisation for portable diagnostics applications.

This offers an alternative which is more related to physics to the usually used transfer function model. The equivalence between the models is shown through a finite difference model and a new analytical formula for the transfer function as a function of transmission line parameters. First, the possibility of modeling an insulated cable with a transmission line model was analyzed through full-wave numerical simulations. The assumption of a transmission line model underlying the transfer function model was shown to be right for a simple cable embedded in tissue imitating gel and the transmission line parameters extracted from this analysis were consistent with analytical formulas derived from the laws of physics. The transmission line model predictions were first compared to experimental and simulated data of the cable transfer function and then, to experimental and simulated data of the resonant behavior as a function of length of cables with different termination conditions. The measured and simulated transfer functions fit perfectly a transmission line model with an analytical expression of the propagating constant. The transmission line model extracted from the transfer function allows to predict the resonant behavior of two cables with different termination conditions

biomedical wearable diagnostic and therapeutic devices using for ergonomics, rehabilitation and neurology. Since it is proved that the power transfer efficiency will be maximized when the phase difference between the transmit currents equals to zero, an optimization problem is formulated to maximize the received power at both receive coils by adjusting the amplitude of transmit coil currents and the receive coil resistances equipped on wearable devices. The formulated problem is nonconvex and we propose an efficient iterative solution by solving a series of geometric programs that approximate the original problem. Both numerical results and simulation results in COMSOL model are provided to demonstrate the effectiveness of the proposed biomedical wearable system and optimization algorithm.

Although the dielectric measurement procedure is straightforward, several factors can introduce uncertainties into dielectric data. Generally, uncertainties are higher in the dielectric measurement of heterogeneous tissues, due to the fact that there is no standard procedure for acquiring and interpreting the dielectric data of heterogeneous tissues. Uncertainties related to tissue heterogeneity can be minimised by estimating the probe sensing volume, defined by the sensing depth and radius, and characterising the tissue distribution within that volume. While several studies have investigated the sensing depth, this work focuses on examining the sensing radius. Both dielectric measurements and numerical simulations with heterogeneous porcine tissues in the microwave range of 0.5-20 GHz have been conducted to quantify the sensing radius and the dielectric contribution of each tissue within the sensing volume. Experiments demonstrate that the sensing radius, which depends on the individual dielectric properties of the constituent tissue types, can be smaller than the probe radius. This work further quantitatively demonstrates that the dielectric contribution of a particular tissue depends on both its location within the sensing volume and its dielectric properties. This study provides fundamental knowledge for accurately interpreting dielectric data of heterogeneous tissues, with the aim of supporting medical device development.

relatively small thicknesses such as 1 cm and 2 cm. In both cases, planar data acquisition of frequency-swept transmission coefficients has been employed. Despite the fact that these algorithms are based on a linear forward model of scattering, they have been capable of providing quantitative estimates of the tissue permittivity due to the experimentally derived kernel of the scattering integral. Here, we demonstrate similar performance with a thicker (about 5 cm) compressed-breast phantom. This thickness is greater or comparable to the median thickness employed in mammography, depending on the view (craniocaudal or mediolateral oblique). The two methods are described in a common mathematical framework for the first time. The importance of the system calibration and the choice of a host medium are discussed through experiments. A new method for focusing onto suspect regions is demonstrated. The limitations of real-time imaging are highlighted along with an outlook to improving the image resolution and suppressing artifacts without sacrificing the reconstruction speed.

Among others, laser ablation has gained a broad clinical acceptance in the treatment of a certain number of solid tumors (e.g. liver, lung, and prostate). In this context, the knowledge of temperature during treatment may be useful to better control the amount of damaged tissue and to subsequently improve clinical outcomes. The objective of this work is to assess the feasibility of two multi-point probes for temperature monitoring during laser ablation. The probes consist of a needle made up of a carbon fiber tube. Each probe embeds an array of 7 fiber Bragg grating sensors. Experiments performed in in vivo animal models (pig livers) show that the probe can reach deep-seated organs and offer the possibility to monitor tissue temperature in seven different positions. This information may be crucial to guide clinicians in the optimization of treatment settings and to improve the accuracy of theoretical models which will pilot future studies to design new heating devices and to develop patient-specific treatments

The sensor enables the measurement of both real and imaginary part of permittivity of the material under test (MUT). The MUT is exposed on the resonator component in a sensing oscillator and the oscillator results in permittivity and conductivity dependent change in the output frequency and output power, respectively. The frequency information is translated into DC voltage using a frequency discriminator and the output power is detected using a power detector. The sensor has been calibrated using iso-propanol, ethanediol and acetone solutions. Methanol-ethanol mixture solutions, in steps of 25% of concentration change, have been used to demonstrate the functionality of the sensor. The selectivity is showed using methanol-ethanol mixtures with concentration differences of 5% around a mixture ratio of 50:50. The chip is 2.3 sq. mm in size and consumes 60 mW power. The sensor measures complex permittivity within 3.7% accuracy for the real part and 4.3% for the imaginary part. As a compact and low-power solution the sensor is a potential candidate for minimal invasive investigations of chemicals and bio-materials at mm-wave frequencies.

Moreover, stent-based devices are being recognized as a minimally invasive alternative to traditional surgery. Hence, the idea of using the body of the stent as the power receiving element is becoming increasingly attractive. The objective of this work is to analyze two near field wireless power transfer methods to stent-based devices, viz., inductive and capacitive coupling. The methods used are lumped element modelling, ac circuit theory, finite-element analysis and experiments to validate the model with excised bovine muscle tissue. Capacitive coupling is proposed as an alternate method due to the transmitter design that can be worn anywhere on the body. It achieves power transfer efficiencies of 2.6% and 1% when placed at depths in muscle tissue of 15 mm and 30 mm respectively. Safety requirements are also met. The capacitive link can accept an input power of 53 mW before exceeding the safe specific absorption rate limit of 1.6 W/kg averaged over 1 g of tissue.

Remote RF-powering provides a reliable wireless power source for such monolithically integrated sensor nodes. Combining highly-integrated ultra-low-power millimeter wave (mm-wave) sensing, wireless power transfer (WPT) and on-chip antenna is a path towards battery-less, fully monolithically integrated, millimeter-sized sensor nodes with only a few milligram of weight. In this work, a passive fully integrated monolithic wireless sensor for mm-wave sensing is presented in a 65 nm CMOS technology, including an on-chip wireless power receiver, on-chip antenna, and a low power transmitter.

Different technologies have been proposed to address these issues, to detect critical events such as stroke or falls, and to monitor automatically human activities for health condition inference and anomalies detection. This paper aims to investigate two types of sensing technologies proposed for assisted living: wearable and radar sensors. First, different feature selection methods are validated and compared in terms of accuracy and computational loads. Then, information fusion is applied to enhance activity classification accuracy combining the two sensors. Improvements in classification accuracy of approximately 12% using feature level fusion is achieved with both Support Vector Machine and K Nearest Neighbor classifiers. Decision-level fusion schemes are also investigated, yielding classification accuracy in the order of 97-98%.

Typically, these dreams contain violent activities. There is a high likelihood of the patient being injured or hurt his bed-partner as a result of these enactments. Continuous monitoring of sleeping RBD patients can prevent these harmful events through timely intervention. This work presents a novel method for continuous observation of RBD patients exploiting fine-grained amplitude and phase information of the wireless channel response. The variations in the wireless channel response as a result of different patient movements are assessed and used to identify RBD episodes. The data obtained is classified using support vector machine and delivers accuracy level of more than 90%.To the best of authors’ knowledge, it is a first attempt at using radio frequency signals to sense RBD in real-time.

One such promising application is the wireless monitoring of transplanted organs, particularly transplanted liver. Ultra-wideband technology is well suited for wireless implanted applications since it allows physical size reduction as well as increased longevity of the implanted devices. However, because of the high attenuation of UWB signals inside the human body, it is necessary to examine their propagation characteristics and demonstrate the feasibility of such application. In this paper, an investigative study involving the liver implanted wireless telemetry link using UWB technology is presented. Measurements using multilayer phantoms and simulations using a human digital model have been conducted within the frequency band of 4.5-6.5 GHz. Multilayer phantom measurements have demonstrated the attenuations ranging between -50 dB and -100 dB over the considered frequency band. A path loss model at the liver area has been obtained from the simulations. Also, the numerical results have shown that the attenuation variation due to respiration-induced organ movements was within 30 dB range with respect to the largest organ movement distance of 40 mm which emphasized the influence of organ movements on the in-body attenuations. Our preliminary link budget evaluation of liver-skin surface communication link including the effect of shadowing and organ movements estimated that it is possible to achieve a high data rate of 10 Mbps with a bit error rate of 10−3 at a distance of about 40 mm.

Such device would be useful in the context of Body Area Networks (BANs) for continuous body-signal monitoring. The proposed adhesive repeater is low profile, and it is designed for dual-band operation at the ISM band (2.4 GHz) and in the ultrawideband (UWB) spectrum (4-10.6 GHz) using a single excitation port. The ISM band is used for in-body communication with the implants and the UWB band for off-body burst communication with the BS. The antenna consists of three layers that grant it compactness and performance robustness. We assess the in-body link between the repeater and a custom-designed miniaturized implantable probe antenna. The study is performed in the frequency-domain with results showing adequate input impedance matching (s11 ≤ -10 dB) and robustness to different body parts. We extend the analysis to time-domain by transmitting a synthetized medical signal between the two antennas. In addition, we evaluate the feasibility of an off-body link for burst communication. Again, the results indicate very good performance by the repeater antenna both in terms of impedance matching (s11 ≤ -10 dB) and preservation of time-signals (fidelity ≥ 75%), which is relevant in impulse radio systems. To the authors’ best knowledge, this is the first time this kind of dual-band adhesive antenna is being proposed for BANs, complete with performance tests using frequency- and time-domain figures-of-merit.

The approach for the determination of magnetic complex susceptibility herein presented reveals itself as simple, rapid, broadband and accurate enough to compete with alternative conventional direct methods requiring complex and expensive instrumentation. In particular, it makes use of indirect equations based on the single order Debye model combined with a punctual set of in vitro SAR measurements. The procedure has a general validity and it can be easily applied in the up-growing field of magnetic hyperthermia studies.

The system utilizes 16 monopole antennas and a modern vector network analyzer (VNA) to measure the phantoms influence on the S-parameters. An iterative algorithm is then used to solve the inverse problem and reconstruct a 2-D plane transecting the phantom. The reconstructed images are compared to the ones recovered from a cylindrical phantom of equivalent phantom media. The results show that both phantoms are possible to reconstruct, although the interior of the Supelec phantom is more challenging.

The early studies of microwave imaging in the therapy monitoring setting are encouraging. For the neoadjuvant therapy application, it would be desirable to achieve the most accurate possible characterization of the tissue properties. One method to achieve increased resolution and specificity in microwave imaging reconstruction is the use of a soft prior regularization. The objective of this study is to develop a method to use magnetic resonance (MR) images, taken in a different imaging configuration, as this soft prior. To enable the use of the MR images as a soft prior, it is necessary to register the MR images to the microwave imaging space. Registration fiducials were placed around the breast that are visible in both the MRI and with an optical scanner integrated into the microwave system. Utilizing these common registration locations, numerical algorithms have been developed to warp the original breast MR images into a geometry closely resembling that in which the breast is pendant in the microwave system.

The dielectric permittivity of the sample, which depends on the chemical composition, is detected using electromagnetic sensors in the microwave frequency range. The sensing system proposed here is based on resonant near-field sensors which are combined with a microfluidic chip. The sample volume of a few picoliters enables single-cell measurements. A novel process featuring a biocompatible polymer material is used for fabricating the microfluidic channel for liquid samples. Two opposed sensing tips are integrated at the bottom of the channel to improve the sensitivity to small dielectric contrasts. They are connected to two resonators, which allows to simultaneously characterize the sample permittivity at two different frequencies. In a proof-of-principle experiment, single cells of the Chinese hamster ovary (CHO-K1) cell line are detected. This shows that the proposed sensing system is suitable for single-cell characterization due to its high sensitivity and spatial resolution. A potential biomedical application is the systematic investigation of various cell types and states to elucidate potential distinguishing characteristics.

These circuits have traditionally used PIN diodes and, more recently, field effect transistors to switch in small values of inductance to shift the coil resonance away from the Larmor frequency. These semiconductor devices can see the full RF power during operation, and will exhibit significant heating, potentially leading to device failure. Even if the device does not reach a destructive heating level, the resistance of the device can increase and effectively degrade the level of blocking in the RF coil. A useful tool for MRI circuit designers would be a thermal model that predicts this change in resistance, and hence degradation in MRI coil blocking, as device temperature rises. This paper presents a method for modeling thermal effects in MRI Q-spoiling control devices. A PIN diode resistance-temperature model is reviewed, and two approaches for field effect transistors that model the temperature rise and subsequent device resistance variation with temperature using SPICE-compatible equivalent circuit elements are covered. Experimental results are presented that validate the form of the models and show that increased device resistance due to temperature rise will degrade MRI blocking by several dB. The ability to model the control device’s thermal characteristics will lead to improved understanding of circuit operation.

visualizing the basis of a novel concept for electromagnetic pathogen detection. Simulations of the split ring structure sensitivity and measurements of its interaction with the target medium provide insights to limitations, which need to be addressed when enhancing the sensor surface for cell-type selectivity using localized aptamer coatings in ongoing research.

As multi-frequency applicators can be exploited to reduce occurrence of undesired hot-spots, an optimal multi-frequency approach is proposed and discussed. Being formulated in terms of a convex programming problem, the globally optimal solution can be determined (but for very special cases). The procedure, presented for the case of scalar fields, can be extended both to the case of vector fields and to the more interesting problem of shaping (rather than just focusing) the Specific Absorption Rate distribution.

We have designed and carried out experiments on an IEEE 802.15.4 based WBAN prototype by measuring the performance of the fat tissue channel in terms of data packet reception with respect to tissue length and power transmission. This paper proposes and demonstrates a high data rate communication channel through fat tissue using phantom and ex-vivo environments. Here, we achieve a data packet reception of approximately 96 % in both environments. The results also show that the received signal strength drops by ∼1 dBm per 10 mm in phantom and ∼2 dBm per 10 mm in ex-vivo. The phantom and ex-vivo experimentations validated our approach for high data rate communication through fat tissue for intra-body network applications. The proposed method opens up new opportunities for further research in fat channel communication. This study will contribute to the successful development of high bandwidth wireless intra-body networks that support high data rate implanted, ingested, injected, or worn devices.

Depending on the band pass filter and antenna characteristics as well as on the focused measurement spot on the human thorax, either the common heartbeat curves or locally specific pulse waveforms, called sphygmograms, are extracted. A Six-Port microwave interferometer, a specific kind of continuous wave radar system, whose block diagram is shown in the blue box, is used for the presented measurements. All novel insights are investigated in combination to substantiate the variety of published heartbeat signal curves, of which five typical examples are depicted in the green box.

The technique was able to measure the extremely low efficiencies associated with deep implant antennas inside a muscle tissue-mimicking liquid phantom. Results were obtained for a range of insulated and un-insulated antennas with efficiencies as low as 0.06%. Analysis showed that while measurement errors were dominated by positioning variability, spurious feed cable radiation is still a significant factor that must be considered. Depending on the radiation characteristics of the antenna under test and the feed cable routing within the phantom, cable radiation could lead to errors of up to 4.5 dB.

from both uplink and downlink radio emissions in a typical urban city. The uncertainties of 4G-induced RF-EMF exposure of an entire population were characterized for the first time taking into account the variability linked to urban propagation environment, information and communication technology usage, EMF respectively from personal wireless devices and Evolved Node B (eNB), as well as uplink throughput. In addition, the study focuses on a sensitivity analysis in order to assess the influence of these parameters on RF-EMF exposure. Globally, results show that the 4G-induced RF-EMF exposure follows a Generalized Extreme Value distribution with an average value of 1.19×10−7 W/kg. Moreover, authors show that, contrary to what have been observed in the 3G-induced RF-EMF exposure, that is, the exposure is dominated by uplink radio emissions, results have highlighted the importance of received power density from eNB to the issue of 4G-induced RF-EMF exposure. In 4G, the uplink exposure from mobiles accounts for only 25% of global exposure, resulting from the high speed of uplink throughput.

A minute increase in health risks such as cancer from RF radiation might lead to significant consequences for health of the general public. A recent U.S. government announcement of discovery of rare cancers in rats exposed to RF radiation is an important occurrence. Note that any new or single report should not be viewed in isolation. The U.S. government project was organized to confront the weaknesses of prior laboratory rodent studies on the potential of RF exposure to impact human health such as cancer in controlled environments. Indeed, several published reports on animal cancer investigations involving prolonged exposures to RF radiation are contentious and perplexing. The discrepancies have presented ambiguity in assessing public health threats from RF exposure. It is the objective of this review to provide a critical and analytical synopsis and assessment on current progress in cancers in rats exposed, lifelong, to RF and microwave radiation. Its focus is on laboratory studies involving cancer production and promotion, and survival of experimental rats. Of special interest is carcinogenesis in the head—cancer development in the head. The question of whether RF exposure from wireless and mobile devices and systems poses a health risk would likely remain equivocal and controversial for some time to come.

In this study, we used stochastic dosimetry, an approach that combines electromagnetic computational techniques and statistics, to assess the fetal exposure to a 4G LTE tablet in realistic scenarios, assessing the influence of the position of the tablet, the gestational age of the fetus and the frequency of the emitting antenna. Results showed that the exposure in terms of Specific Absorption Rate (SAR) was within the limits of the ICNIRP 1998 general public Guidelines in all the considered scenarios. The position of the tablet was very influential for the induced SAR in the fetus, resulting in Quartile Coefficient of Dispersion always higher than 40%. The level of exposure for the later pregnancy was found to be higher than those for the early pregnancy. As to the effect of the emitting frequency of the tablet, we found that the higher the frequency, the lower the induced SAR in the fetus.

ranging from hospital to indoor and outdoor environments, e.g., for monitoring of vital signs and/or tracking of human activities. This manuscript reviews the standard architectures for short-range biomedical radars and presents recently-proposed hybrid schemes which combine different operation modes, leading to performance improvement. Specifically, hybridizations associated with Doppler, frequency-modulated continuous-wave (FMCW), and tone-ranging-based schemes are provided from theoretical and simulation viewpoints. Some experiments on vital-sign monitoring and human-aware localization are also reported.