In-body Applications Research Articles

Optimizing Silver Nanowire Synthesis for In-Body Applications

Optimizing Silver Nanowire Synthesis for In-Body Applications

Energy-Aware AI-Driven Framework for Edge-Computing-Based IoT Applications

The significant growth in the number of Internet of Things (IoT) devices has given impetus to the idea of edge computing for several applications. In addition, energy harvestable or wireless-powered wearable devices are envisioned to empower the edge intelligence in IoT applications. However, the intermittent energy supply and network connectivity of such devices in scenarios including remote areas and hard-to-reach regions such as in-body applications can limit the performance of edge computing-based IoT applications. Hence, deploying state-of-the-art convolutional neural networks (CNNs) on such energy-constrained devices is not feasible due to their computational cost. Existing model compression methods, such as network pruning and quantization can reduce complexity, but these methods only work for fixed computational or energy requirements, which is not the case for edge devices with an intermittent energy source. In this work, we propose a pruning scheme based on deep reinforcement learning (DRL), which can compress the CNN model adaptively according to the energy dictated by the energy management policy and accuracy requirements for IoT applications. The proposed energy policy uses predictions of energy to be harvested and dictates the amount of energy that can be used by the edge device for deep learning inference. We compare the performance of our proposed approach with existing state-of-the-art CNNs and data sets using different filter-ranking criteria and pruning ratios. We observe that by using DRL-driven pruning, the convolutional layers that consume relatively higher energy are pruned more as compared to their counterparts. Thereby, our approach outperforms existing approaches by reducing energy consumption and maintaining accuracy.

Improving Lateral Resolution in 3-D Imaging With Micro-beamforming Through Adaptive Beamforming by Deep Learning.

There is an increased desire for miniature ultrasound probes with small apertures to provide volumetric images at high frame rates for in-body applications. Satisfying these increased requirements makes simultaneous achievement of a good lateral resolution a challenge. As micro-beamforming is often employed to reduce data rate and cable count to acceptable levels, receive processing methods that try to improve spatial resolution will have to compensate the introduced reduction in focusing. Existing beamformers do not realize sufficient improvement and/or have a computational cost that prohibits their use. Here we propose the use of adaptive beamforming by deep learning (ABLE) in combination with training targets generated by a large aperture array, which inherently has better lateral resolution. In addition, we modify ABLE to extend its receptive field across multiple voxels. We illustrate that this method improves lateral resolution both quantitatively and qualitatively, such that image quality is improved compared with that achieved by existing delay-and-sum, coherence factor, filtered-delay-multiplication-and-sum and Eigen-based minimum variance beamformers. We found that only in silica data are required to train the network, making the method easily implementable in practice.

Glucose-Responsive Boronic Acid Hydrogel Thin Films Obtained via Initiated Chemical Vapor Deposition.

Glucose-responsive materials are of great importance in the field of monitoring the physiological glucose level or smart insulin management. This study presents the first vacuum-based deposition of a glucose-responsive hydrogel thin film. The successful vacuum-based synthesis of a glucose-responsive hydrogel may open the door to a vast variety of new applications, where, for example, the hydrogel thin film is applied on new possible substrates. In addition, vacuum-deposited films are free of leachables (e.g., plasticizers and residual solvents). Therefore, they are, in principle, safe for in-body applications. A hydrogel made of but-3-enylboronic acid units, a boronic acid compound, was synthesized via initiated chemical vapor deposition. The thin film was characterized in terms of chemical composition, surface morphology, and swelling response toward pH and sucrose, a glucose–fructose compound. The film was stable in aqueous solutions, consisting of polymerized boronic acid and the initiator unit, and had an undulating texture appearance (rms 2.1 nm). The hydrogel was in its shrunken state at pH 4–7 and swelled by increasing the pH to 9. The pKa was 8.2 ± 0.2. The response to glucose was observed at pH 10 and resulted in thickness shrinking.

Compact multi-band implantable antenna designs for versatile in-body applications

In this paper, a quad-band implantable antenna (QBIA) and its triple-band miniaturized configuration are presented. The primary radiator of the proposed QBIA consists of four different types of concentric resonators excited by a microstrip feed line. The QBIA design has dimensions of 15 × 15 × 1.27 mm3, and it covers the Medical Device Radiocommunications Service (MedRadio), Medical Implant Communication Service (MICS), Medical Telemetry Service (WMTS), and Industrial, Scientific, and Medical (ISM) bands. The proposed antenna was fabricated to validate the numerical design, and the characteristics of its return loss and radiation patterns were measured in minced meat from pork. The miniaturized version of the QBIA has an ultra-compact size of 4.16 mm3 (4 × 4 × 0.26 mm3), and it offers a triple-band operation covering the ISM and WMTS bands. The proposed triple-band implantable antenna (TBIA) was achieved by using a thinner substrate and optimizing all design parameters of the QBIA. To the best of our knowledge, the suggested QBIA with the novel configuration is the first implantable antenna that simultaneously covers almost all frequency bands allocated for biotelemetry applications. Also, the proposed TBIA is the most miniature triple-band implantable antenna presented in the recent literature, considering the application frequencies.

Effect of Breathing on UWB Propagation Characteristics for Ingestible and Implantable Devices

Wireless in-body devices are those in which a medical sensor is introduced&#x2013;implanted or ingested&#x2013; inside the human body and communicates with a remote node. Some in-body applications demand high data rates, so ultrawideband (UWB) spectrum has been proposed as a good candidate because of its large bandwidth available. Besides, breathing can lead to internal movement of the torso and consequently, of devices installed in this area. Thus, the radio channel performance can be affected by such movement leading to a malfunction of the radio interface of the medical device. This work aims at analyzing the effect of breathing on the propagation channel by means of <i>in vivo</i> measurements in living animal models. Continuous wave (CW) measurements have been carried out for five different frequencies in the lower part of the UWB band, and the effects of breathing on the relative received power (module and phase) are analyzed and discussed.

A Multiscale Communications System Based on Engineered Bacteria

Although molecular communication systems have been shown to bear great potential for many useful in-body applications, they require the intervention, action, or input of an out-of-body actor. From an Internet of Bio-Nano Things perspective, a successful overall network aims to bring together the two links belonging to the in-body and out-of-body networks for end-to-end communications. For most applications, the uplink from the in-body sensor is more significant since it provides the multi-scalar connection required to relay the information sensed and carried by the molecular communication system to a macro-scale smart terminal. This article proposes two different mechanisms to sense the output of the molecular communication system and transmit the information to an on-body reader. Each mechanism involves different genetically engineered bacteria and specific antenna designs. An experimental setup is provided to demonstrate each proposed concept. The results constitute a proof of concept to detect the in-body bacterial activity from the on-body reader.

UWB RSS-Based Localization for Capsule Endoscopy Using a Multilayer Phantom and In Vivo Measurements

In recent years, the localization for capsule endoscopy applications using ultrawideband (UWB) technology has become an attractive field of investigation due to its potential benefits for patients. The literature concerning performance analysis of radio frequency-based localization techniques for in-body applications at UWB frequencies is very limited. Available studies mainly rely on finite-difference time-domain simulations, using digital human models and on experimental measurements by means of homogeneous phantoms. Nevertheless, no realistic analysis based on multilayer phantom measurements or through in vivo experiment has been reported yet. This paper investigates the performance of the received signal strength-based approach for 2-D and 3-D localizations in the UWB frequency band. For 2-D localization, experimental laboratory measurements using a two-layer phantom-based setup have been conducted. For 3-D localization, data from a recently conducted in vivo experiment have been used. Localization accuracy using path loss models, under ideal and non-ideal channel estimation assumptions, is compared. Results show that, under nonideal channel assumption, the relative localization error slightly increases for the 2-D case but not for the in vivo 3-D case. Impact of receivers selection on the localization accuracy has also been investigated for both 2-D and 3-D cases.

Robust Ultraminiature Capsule Antenna for Ingestible and Implantable Applications

Progress in implantable and ingestible wireless biotelemetry requires versatile and efficient antennas to communicate reliably from a body. We propose an ultraminiature 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 of 50 Ω. The antenna is synthesized and miniaturized using a hybrid analytical-numerical approach, and then optimized to conform to the inner surface of a 17 mm long biocompatible encapsulation (7 mm diameter). The substrate is 50 μm thick. The capsule antenna is analyzed both in simplified and anatomically realistic heterogeneous phantoms. It remains matched at common implantation sites and through the whole gastrointestinal tract. Enhanced robustness allows using the antenna for a wide range of in-body applications. Computed reflection coefficients and radiation performance both show good agreement with measurements. The far field is characterized with the direct illumination technique using an analog fiber optic link. The realized gain (measured max. value -19.6 dBi) exceeds the counterparts by about 3 dBi. The proposed antenna contributes to the further development of a new generation of miniature in-body devices that involve complex and dense integration of sensors, logic, and power source.

Zigbee MAC 프로토콜기반 인체 응용을 위한 나노 네트워크의 슈퍼 프레임 설계

Zigbee MAC 프로토콜기반 인체 응용을 위한 나노 네트워크의 슈퍼 프레임 설계

Experimental Path Loss Models for In-Body Communications Within 2.36-2.5 GHz.

Biomedical implantable sensors transmitting a variety of physiological signals have been proven very useful in the management of chronic diseases. Currently, the vast majority of these in-body wireless sensors communicate in frequencies below 1GHz. Although the radio propagation losses through biological tissues may be lower in such frequencies, e.g., the medical implant communication services band of 402 to 405MHz, the maximal channel bandwidths allowed therein constrain the implantable devices to low data rate transmissions. Novel and more sophisticated wireless in-body sensors and actuators may require higher data rate communication interfaces. Therefore, the radio spectrum above 1GHz for the use of wearable medical sensing applications should be considered for in-body applications too. Wider channel bandwidths and smaller antenna sizes may be obtained in frequency bands above 1GHz at the expense of larger propagation losses. Therefore, in this paper, we present a phantom-based radio propagation study for the frequency bands of 2360 to 2400MHz, which has been set aside for wearable body area network nodes, and the industrial, scientific, medical band of 2400 to 2483.5MHz. Three different channel scenarios were considered for the propagation measurements: in-body to in-body, in-body to on-body, and in-body to off-body. We provide for the first time path loss formulas for all these cases.

Modeling and Experimental Analysis of an In-body Area Nanonetwork

Nanotechnology is gaining more and more consensus in several application fields, comprised in-body applications. Innovative therapies and diagnostic approaches are based on the use of injections or oral delivery of nanoparticles. The acceleration of this type of development makes very urgent a deeply and accurate analysis of the interaction between the nanoparticles and the biological fluid where the nanoparticles are immersed. In this paper, we focus on Titanium (Ti and its alloy (e.g.; TiO2) systems, given their specific features in terms of density, lack of cytotoxic effects, etc.. Specifically, we design and study an in-body system by characterizing the emission and diffusion processes. Further, we propose an experimental study of the morphology and other important characteristics (e.g. the pH of the particles, and the dielectric constant of the solution) of nano-TiO2 systems when immersed in a Ringer solution, in order to derive important information related to their potential toxicity inside the human body.

LINK BUDGET OF MAGNETIC ANTENNAS FOR INGESTIBLE CAPSULE AT 40 MHZ

Magnetic antennas are suitable in short range medical in-body applications because they are less perturbed in the presence of the human tissues comparing to electrical antennas. After a preliminary study on magnetic antennas designed separately at 40 MHz with a matching system, a link budget between a spiral coil ingestible capsule transmitter antenna and a square coil onbody receiver antenna has been established in the presence of the human body. The efficiency (ratio of received power to transmitted power) of the magnetic induction link through a homogeneous human body (muscle) is equal to 0.6 % when the TX (transmitter) capsule is in front of the RX (receiver) antenna. If the transmission channel is a three-layered human body (muscle / fat / skin) the performances of the inductive link can be enhanced and the efficiency reaches 0.8 %. These performances can be improved (up to 1 %) when the dimensions of the receiver antenna increase. Consequently, the power consumption can be reduced and hence the battery life of the wireless capsule increases. Additionally, when the TX antenna is located randomly at an arbitrary orientation and position, the efficiency of the magnetic induction link can be improved by orienting the RX antenna parallel and perpendicularly to the human body surface.

Epidermal electronics for health and fitness monitoring

Medical deployment of electronics is frequently hampered by boxy, rigid packaging. Biological tissues are soft and curved, while electronic components are hard and angular. The mechanical mismatch can be alleviated by re-packaging electronics in radical new form factors. MC10 has developed a technology platform using ultra-thin components linked with stretchable interconnects and embedded in low modulus polymers which provide an excellent match to biological tissues. The MC10 platform is based on packaging today's high-performance active components in new mechanical form factors. The platform has three key elements: thin silicon embedded in film for flexibility, silicon transfer from foundry CMOS wafers to polymer-coated carriers and flexible metallic interconnect on polymer. On-body and in-body applications are both well suited to the technology platform. Skin-mounted systems resemble electronic tattoos, and can be worn for extended periods without discomfort while providing continuous monitoring. Inside the body, instrumented catheters provide a practitioner with unprecedented electrical information about the interior of the heart.

Computational study of ultra-wideband wave propagation into the human chest

Ultra-wideband (UWB) has potential applications in a variety of medical areas such as implant wireless sensors, microwave hyperthermia, imaging and radar. The wave propagation inside the human body must be known for an efficient system design of these different e-health applications. Nevertheless, little is known about the propagation of UWB signals inside the human body despite the enormous research efforts devoted to characterising radio propagation around the body. Therefore in this study, the UWB wave propagation through the human chest is characterised by electromagnetic simulations. For this sake, a voxel model of the human body that incorporates the frequency-dependent material properties of the human tissues is used. The wave propagation for line-of-sight (LOS) scenarios in the frequency bands of 100-1000 MHz and 1-5 GHz are evaluated. Both vertical and horizontal wave polarisations are considered. The power radiographs of the received signals inside the human chest are presented, which display the frequency and polarisation-dependent variations. The spectral analysis of the received signals reveals that the frequency range of 100-250 MHz, offers the minimum propagation loss. This frequency range of 250-1000 MHz is depicted as a region with less variant loss against frequency. Furthermore, the power delay profile (PDP) and the root mean square delay spread of the in-body channels is presented for different depths inside the body. These insightful results further the understanding of the propagation behaviour of UWB signals inside the human body, which will ease the development of in-body e-health applications.