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A Communication Link Analysis Based on Biological Implant Wireless Body Area Networks
Abstract
The rapid growth in remote healthcare services and biomedical demands has seen novel developments in wireless body area networks (WBANs). The WBAN can be seen as an integration of intelligent networks, which permits devices and sensors to work together to obtain a series of critical physiological parameters, such as blood flow velocity and heartbeat frequency. Analysis of WBAN radio frequency communication systems is the key factor and the critical research challenge that determines system performance, such as achievable transmission distance, data rate and so forth. The human head is an area of particular potential in WBAN design that is worthy of attracting more attention than its limited literature to date. This paper is primarily focused on the one of the most detailed comprehensive multi-modal imaging-based anatomical human head models. This is a multimodal imaging-based detailed anatomical model, denoted by the acronym MIDA, this features 153 structures at a high resolution of up to 500 mu m, including numerous distinct muscles, bones and skull layers in the license-free 2.4 GHz industrial, scientific, and medical (ISM) band. It presents and compares a set of advanced simulation methods and then proposes a path loss simulation flat phantom, semi-empirical path loss models for typical homogeneous tissues and the anatomical human head MIDA model. The bit error rate (BER) performances of the MIDA model fading channel using binary phase shift keying (BPSK) and pulse-amplitude modulation (PAM) are obtained. Furthermore, achievable transmission distances for several data rates for predetermined acceptable BERs are accomplished. The results show that PAM promises longer transmission distances than BPSK when using both high and low data rates. The proposed communication systems can be applied to optimize implantation communication system scenarios and biotelemetry applications.
... As proved in [16][17][18], transmission energy attenuation evaluation of the in-body to in-body and in-body to on-body communication channels can be modeled employing the same PL model. The statistical PL in dB at the distance d can be statistically expressed as: ...
... The PL values depend on the positions of the biosensor nodes and the transmission channels. According to [17][18], the related PL parameters are listed in Table I. TABLE I. PATH LOSS PARAMETERS REPORTED IN [17][18]. ...
... According to [17][18], the related PL parameters are listed in Table I. TABLE I. PATH LOSS PARAMETERS REPORTED IN [17][18]. ...
... Also, the radio frequency (RF) communication module has been identified as the consumer of the majority of the energy in a WBASN system [3], and thus needs in-depth investigation. Wireless communication within the human body experiences a high energy attenuation budget for wireless in-body sensor networks [8][9][10][11]. Thus, an accurate path loss model plays a vital role in analyzing the propagation loss and communication link. However, there is a dearth of literature on signal propagation loss within human body. ...
... One technique capable of improving the WBASN in-body sensor node lifetime is energy efficient routing protocol design [11,[13][14]. In [11], the transmission distance between sensor nodes and the coordinator is related to energy consumption, demonstrating the higher transmission power needed for longer ranges. ...
... One technique capable of improving the WBASN in-body sensor node lifetime is energy efficient routing protocol design [11,[13][14]. In [11], the transmission distance between sensor nodes and the coordinator is related to energy consumption, demonstrating the higher transmission power needed for longer ranges. A thermally aware energy efficient protocol, known as M-ATTEMPT, has been described in [13]. ...
... . The proposed typical structure of the health IoT system. WBANs differ from traditional wireless communication systems in terms of propagation medium, transmission power restrictions and human tissue/organ safety requirements [5]. Over 65% of the human intra-body region is composed of water. ...
... Kurup et al. proposed the first in-body path loss (PL) model for homogeneous human muscle tissue at 2.45 GHz in 2009 [14]. Later they reported an extended PL model, which includes the WBANs differ from traditional wireless communication systems in terms of propagation medium, transmission power restrictions and human tissue/organ safety requirements [5]. Over 65% of the human intra-body region is composed of water. ...
... Moreover, organ-tissue communications and drug transportation is via the blood [6]. This makes radio frequency (RF) signals remarkably attenuated when transmitting data through tissues/organs, even at relatively low frequencies such as the medical implant communication service (MICS) 402-405 MHz band proposed by the IEEE [5]. The 2.45 GHz industrial, scientific and medical (ISM) radio band is investigated in this article, as this brings advantages for WBAN systems. ...
In this paper, an analytical and accurate in-to-out (I2O) human body path loss (PL) model at 2.45 GHz is derived based on a 3D heterogeneous human body model under safety constraints. The bit error rate (BER) performance for this channel using multiple efficient modulation schemes is investigated and the link budget is analyzed based on a predetermined satisfactory BER of 10−3. In addition, an incremental relay-based cooperative quality of service-aware (QoS-aware) routing protocol for the proposed I2O WBAN is presented and compared with an existing scheme. Linear programming QoS metric expressions are derived and employed to maximize the network lifetime, throughput, minimizing delay. Results show that binary phase-shift keying (BPSK) outperforms other modulation techniques for the proposed I2O WBAN systems, enabling the support of a 30 Mbps data transmission rate up to 1.6 m and affording more reliable communication links when the transmitter power is increased. Moreover, the proposed incremental cooperative routing protocol outperforms the existing two-relay technique in terms of energy efficiency. Open issues and on-going research within the I2O WBAN area are presented and discussed as an inspiration towards developments in health IoT applications.
... Consequently, antennas are utilized as the mediator between the examined tissue and the base station [3]. It is the main element in the transmission process and depends on wireless links named "biotelemetry" for the data transfer [4]. However, designing antennas for medical applications depends on the industrial, scientific and medical (ISM) band for medical telemetry operations, but recently medical implant communication service (MICS) band (402-405 MHz) has been allocated which is regulated by the United States Federal Communications Commission and the European Radio Communications Committee for bi-directional bio-telemetry operations [5]. ...
... As a result, antennas are used as a bridge between the tested tissue and the base station [3]. It is the primary component in the transmission process and relies on wireless networks known as "biotelemetry" for data transfer [4] Table 1 Antenna structure ...
A multilayer antenna is designed for MICS and ISM bands. The performance of the antenna was evaluated considering native and coagulated liver tissues. Tissue diffuse reflectance was measured to show the difference in biological characteristics.
... The rapid evolution of healthcare wireless body area networks (WBANs) reflects the escalating need for realtime smart infrastructures to reliably monitor key gauges of the human body [1,2]. To this aim, an impressive variety of such systems has been developed in terms of specialized antennas [3][4][5] and advanced biomedical applications [6,7]. On the other hand, the assessment of electromagnetic radiation effects of several WBANs upon the human body and particularly on the thyroid has lately become a critical problem [8,9]. ...
A methodical approach for assessing the effects of an external point source to a non-spherical model of the human neck is presented in this paper. The neck model consists of multilayered spheres to represent the skin, fat, muscle tissues, thyroid, and esophagus. The novel geometry enables the formulation of dyadic Green’s functions to accurately calculate the electric fields, considering the suitable surface boundary conditions and the superposition principle. Numerical outcomes for a Hertz dipole (i.e., a wireless network antenna) at the frequency of 2.4 GHz certify the benefits of the technique and elaborately describe the responsiveness of the neck/thyroid to the selected source.
... An intelligent healthcare system with a target-specific flexible quality of service (QoS) consisting of an intelligent gateway, wireless communication links, and a set of sensor nodes is to periodically monitor and communicate human essential signals to a distant healthcare server. The eHealth-care model remotely monitors the health status of the patients and accessible for physicians and nurses [4]. Besides, a large amount of data gathered enables researchers to develop advanced medicare devices. ...
One of the major applications of Wireless Body Area Networks (WBANs), and the Internet of Things is the Electronic Health-Care systems. The progress in WBANs, and implanted health monitoring technologies have strong potential to alter the future of healthcare services by enabling ubiquitous monitoring of patients. An energy-efficient protocol is an important factor in the operation of eHealth care systems. A hybrid energy-efficient routing protocol is proposed in this paper for the distributed wireless body area network. In which a hybrid communication method and a new synchronization scheme are discussed. The hybrid communication enhances the network lifetime, and the synchronization scheme will consume less energy by avoiding collisions. The performance of the proposed protocol is analyzed, and it is compared with three baseline routing protocols at the 2.4 GHz ISM band with two ultra-low power transceivers.
... IMD system architecture (Adapted from[23].) ...
Smart Healthcare is an integral part of Smart Cities. Modern medical devices are becoming increasingly software dependent. Doctors and patients are now using their smart-phones to control and monitor Implantable Medical Devices (IMDs) such as cardiac implants, insulin pumps, deep brain neurostimulators, etc. via the Internet or Bluetooth connections. Although such connectivity expands the devices' ability to fulfill healing and diagnostic functions in a quick and cost-effective manner and can help save many lives, too much reliance on software also results in exposure to several security threats. Control of such devices via the underlying communication network may allow attackers to exploit the critical system vulnerabilities of these devices. Attackers could manipulate the settings of these devices and may try to harm the patients and these malicious attacks can originate from anywhere in the world. However, there have been very few real attempts to hack such devices and harm patients. We investigate the practical security risks involved with the use of IMDs and the motivations for an attacker to hack these devices. While some risks discussed in research are genuine and can be prevented using various security measures, it seems that quite a few risks are mere exaggerations. In our paper, we review the aspects mentioned above of IMDs and also outline some practical security measures that can further enhance the security and privacy for patients using IMDs.
... In WBANs, where a maximum of 256 nodes can exist per network within a volume of 6m 3 and an operating range 3m [14]. Moreover, while connecting to the Internet, WBANs ranging from a few sensors up to tens to hundreds of sensors communicating with a gateway. ...
Due to the hardship of expedition, instability, and fluctuation of rough weather, continuous walking, hassle and mental stress during the Hajj at Makkah in Saudi Arabia, many pilgrims get injured, sick and tired. Besides, those who are suffering from various chronic diseases may also contract severe heart, chest, abdominal, and kidney diseases along with some infectious diseases like influenza and thus complicate the overall physiological functions of the patients. Other than the problems of diseases, overcrowd at religious sites also cause other noteworthy problems including trauma, missing and lost pilgrims, and even death. And so, it is a vital issue and a big challenge to provide the best healthcare facilities and services for pilgrims and their real-time monitoring during Hajj. Wireless body area network (WBAN) is a promising technology for healthcare. But, providing suitable communication network between WBAN and healthcare providers is another challenging issue. Modern information and communication technology (ICT) systems can make it feasible that WBANs will connect itself to the Internet to transmit data and efficiently administer the proper delivery of healthcare services among the pilgrims during Hajj. Therefore, integration of the medical technology and ICT in the healthcare sector is a prominent research issue especially for WBAN. However, the coverage of a WBAN is limited to only about 1-2 meter. Therefore, to largely extend its coverage area it should interwork with other wireless networks which will facilitate connectivity between those sensor devices of WBAN and the outside world. Due to the limitations of self-expandable, selfconfiguring and self-healing nature of other existing conventional wireless communication technologies, wireless mesh network (WMN) is the suitable and potential communication technology for transferring pilgrims' health information to the healthcare stations crowd environment at Hajj ritual sites. WMN, due to its self-expandable nature can be deployed with WBAN during Hajj for pilgrims' health monitoring which requires extending the coverage of the environment. Therefore, the main objective of this research is to design a conceptual healthcare framework for pilgrims' health monitoring during Hajj by integrating WBAN and WMN technologies.
... Wearable electronics have received an extensive interest because of the great potential of future wireless body area networks (WBANs) [180], which can be used to monitor the movement [181] or vital signs of human being [182]. In particular, there is a growing demand for cost-effective textile antennas that can endure stretching and moisture for future WBAN and sensing systems [183]. ...
Aiming at the development trends, the problems, and challenges met for the current non-destructive testing (NDT) and structural health monitoring (SHM) technologies, we introduce a kind of passive wireless radio frequency identification (RFID) sensor, and uncover its potential application in SHM, especially in the area of aerospace. We categorize the problems in the applications of RFID sensing technique for SHM from multiple perspectives: sensing mechanism, signal measurement, feature analysis and extraction. Moreover, the future directions for RFID sensing technique are pointed out as well. This paper can provide guidance for the application of RFID sensing technique in the area of SHM. © 2017, Editorial Department of Journal of NUAA. All right reserved.
... Wearable electronics have received an extensive interest because of the great potential of future wireless body area networks (WBANs) [180], which can be used to monitor the movement [181] or vital signs of human being [182]. In particular, there is a growing demand for cost-effective textile antennas that can endure stretching and moisture for future WBAN and sensing systems [183]. ...
In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.
In this paper, parametric analysis of LoRa sensor network data rate and packet time on air is presented. Notably, LoRa transceivers use Chirp Spread Spectrum (CSS) modulation and Forward Error Correction (FEC) technique that depends on chirp spreading factor, code rate and bandwidth. These parameters, among others significantly affect the operating data rate and packet transmission time, otherwise known as packet time on air. The focus in this paper is to evaluate the impact of the key parameters on the LoRa sensor network data rate and packet time on air. The parametric analysis was done by keeping other parameters constant and varying one specific parameter and then computing the desired parameter value. For the bit rate, the results show that for code rate, CR = 1, the bit rate for SF of 7 is 5468.8 bps whereas that for SF of 12 is 293.3 bps. Also, the bit rate decreases with increase in CR; notably, for SF of 7 at CR =1 the bit rate is 5468.8 bps whereas at CR =4 the bit rare is 3418.0 bps. In addition, the bit rate increases with the bandwidth. For the time on air ,TOA, with payload, PL size of 10 bytes, the results show that for SF of 7 the TOA is 41.216 ms while the TOA is 991.232 ms for SF of 12. Also, the TOA increases exponentially with SF. Remarkably, the data rate and TOA together determine how much energy is required to transmit a given amount of data over a given communication range. Hence, knowing how the other parameters affect the data rate and packet transmission time can help LoRa sensor network designers to select appropriate parameter values to suit their applications.
The display design of the Internet of Things prototype system is the top priority of the design of the display space, and it is also a problem to be studied in the future development of the display space. However, the current research on the display design direction of IoT prototype system is not deep enough. This article mainly studies the display design model based on the Internet of Things prototype system. This article mainly uses the related technology of IoT heterogeneous protocol to analyze the structure of the IoT prototype system and proposes to use the heterogeneous network to speculate the future development trend of the IoT. In the aspect of display design, applications such as network information retrieval and data mining at the level of missions are accelerated in depth so that the arrangement of multiple factors is more reasonable. Finally, the data conversion function is used to design each port in the IoT accessor architecture. The protocol is adapted and converted, and the parsed protocol is uniformly encapsulated and uniformly transmitted on the platform. The model in this article integrates various heterogeneous detection networks, realizes the standardized operation of top-level applications, and completes the decoupling of top-level applications. It is encapsulated in a unified protocol and meets the standard operation requirements of web applications. The experimental data in this article show that the frequency of the audio signal designed by the system under normal working conditions is mostly concentrated at about 180 Hz, and the highest frequency value is less than 800 Hz; when the system has a partial discharge failure, the frequency of the audio signal is mostly concentrated between 1400 Hz and 1800 Hz. The experimental results of this article show that the prototype system of the Internet of Things can identify and judge the state of the display design model. Applying it in practice can effectively solve practical problems such as large-scale data storage of the Internet of Things.
Medical industries are continuously working towards the development of wearable theragnostic devices which enable monitoring various ailments in the body and then transmitting them to the base-station. The antenna design is of prime importance where the suitable design guarantees proper communication between the antenna and the base-station. In this paper, a co-planar wave-guide antenna is proposed for the use in the medical implant communication service (MICS) band for data transmission. The proposed antenna is studied for ex-vivo applications where the antenna is simulated for bovine intramuscular fat (adipose tissue). The preliminary results showed that the antenna radiates in MICS band. Two types of samples are tested; namely, native fat and boiled fat. The boiled fat is used in order to represent the infected fat tissue. Hence, the antenna was implanted into the fat samples and the results revealed noticeable variations in the radiation characteristics between native and boiled fat. Different parameters of the proposed antenna including the reflection coefficient (S 11 ), radiation patterns, gain, efficiency, and front-to-back ratio are investigated. The simulations showed that S 11 parameter was − 12.4 dB in MICS band for the normal fat. On the other hand, the measured S 11 values were − 12.3 dB for the native samples and − 9.9 dB for the boiled fat samples. To assert the variation in the biological characteristics of the boiled fat as compared to those of the native fat, diffuse optical measurements of the examined samples were investigated. Such variation in the light scattering and absorbance by the tissue is responsible for varying the S 11 parameter for each case. The results have shown that the proposed design is a good candidate for detecting the change in biological tissue.
The implantable body sensor network (IBSN) has many promising applications. The sensors in the network support different functionalities, such as glucose monitoring and strain measurement in bones. These sensors work with a central hub that communicates with a receiver outside the body. A reliable communication link between these sensors is essential. In this paper, the path loss between elliptic circular loop antennas in muscle and two different bones (the humerus and femoral bone) has been estimated at 403 MHz inside the CST Katja voxel body model. A 33 dB larger path loss is obtained between muscle and humerus antennas than that between muscle and femoral bone antennas. Hence, a standard link with an ideal phase shift keying (PSK) can be only built up from the femoral bone to the the muscle above the hip. The results in this paper provide a good source of data for link budget calculations for bone implantable applications
Computational modeling and simulations are increasingly being used to complement experimental testing for analysis of safety and efficacy of medical devices. Multiple voxel- and surface-based whole- and partial-body models have been proposed in the literature, typically with spatial resolution in the range of 1-2 mm and with 10-50 different tissue types resolved. We have developed a multimodal imaging-based detailed anatomical model of the human head and neck, named "MIDA". The model was obtained by integrating three different magnetic resonance imaging (MRI) modalities, the parameters of which were tailored to enhance the signals of specific tissues: i) structural T1- and T2-weighted MRIs; a specific heavily T2-weighted MRI slab with high nerve contrast optimized to enhance the structures of the ear and eye; ii) magnetic resonance angiography (MRA) data to image the vasculature, and iii) diffusion tensor imaging (DTI) to obtain information on anisotropy and fiber orientation. The unique multimodal high-resolution approach allowed resolving 153 structures, including several distinct muscles, bones and skull layers, arteries and veins, nerves, as well as salivary glands. The model offers also a detailed characterization of eyes, ears, and deep brain structures. A special automatic atlas-based segmentation procedure was adopted to include a detailed map of the nuclei of the thalamus and midbrain into the head model. The suitability of the model to simulations involving different numerical methods, discretization approaches, as well as DTI-based tensorial electrical conductivity, was examined in a case-study, in which the electric field was generated by transcranial alternating current stimulation. The voxel- and the surface-based versions of the models are freely available to the scientific community.
In this paper, a compact UWB MIMO antenna with enhanced isolation for WBAN applications is proposed. The proposed antenna consists of two folded antenna elements, a ground plane, and a T-shaped isolator. The overall dimension is 26 mm × 26 mm × 5 mm. In order to enhance the isolation between the two antenna elements (S21), the T-shaped isolator is placed between antenna elements. Simulated results show that the proposed antenna on a human equivalent phantom has the 10-dB return loss bandwidth of 5.8 GHz ranging from 3.0 to 8.8 GHz, the isolation of less than -12 dB and ECC of less than 0.1 within the operating frequency band. The antenna provides the pattern diversity in H-plane, which can improve the performance of the antenna diversity.
Computational modeling and simulations are increasingly being used to complement experimental testing for analysis of safety and efficacy of medical devices. Multiple voxel- and surface-based whole- and partial-body models have been proposed in the literature, typically with spatial resolution in the range of 1–2 mm and with 10–50 different tissue types resolved. We have developed a multimodal imaging-based detailed anatomical model of the human head and neck, named “MIDA”. The model was obtained by integrating three different magnetic resonance imaging (MRI) modalities, the parameters of which were tailored to enhance the signals of specific tissues: i) structural T1- and T2-weighted MRIs; a specific heavily T2-weighted MRI slab with high nerve contrast optimized to enhance the structures of the ear and eye; ii) magnetic resonance angiography (MRA) data to image the vasculature, and iii) diffusion tensor imaging (DTI) to obtain information on anisotropy and fiber orientation. The unique multimodal high-resolution approach allowed resolving 153 structures, including several distinct muscles, bones and skull layers, arteries and veins, nerves, as well as salivary glands. The model offers also a detailed characterization of eyes, ears, and deep brain structures. A special automatic atlas-based segmentation procedure was adopted to include a detailed map of the nuclei of the thalamus and midbrain into the head model. The suitability of the model to simulations involving different numerical methods, discretization approaches, as well as DTI-based tensorial electrical conductivity, was examined in a case-study, in which the electric field was generated by transcranial alternating current stimulation. The voxel- and the surface-based versions of the models are freely available to the scientific community.
Physical-layer characterization is important for design of in-to-out body communication for wireless body area networks (WBANs). This paper numerically investigates the path loss and absorption of an in-to-out body radio frequency (RF) wireless link between an endoscopy capsule and a receiver outside the body using a 3D electromagnetic solver. A spiral antenna in the endoscopy capsule is tuned to operate in the Medical Implant Communication Service (MICS) band at 402 MHz, accounting for the properties of the human body. The influence of misalignment, rotation of the capsule, and three different human models are investigated. Semi-empirical path loss models for various homogeneous tissues and 3D realistic human body models are provided for manufacturers to evaluate the performance of in-body to out-body WBAN systems. The specific absorption rate (SAR) in homogeneous and heterogeneous body models is characterized and compliance is investigated.
The Virtual Family computational whole-body anatomical human models were originally developed for electromagnetic (EM) exposure evaluations, in particular to study how absorption of radiofrequency radiation from external sources depends on anatomy. However, the models immediately garnered much broader interest and are now applied by over 300 research groups, many from medical applications research fields. In a first step, the Virtual Family was expanded to the Virtual Population to provide considerably broader population coverage with the inclusion of models of both sexes ranging in age from 5 to 84 years old. Although these models have proven to be invaluable for EM dosimetry, it became evident that significantly enhanced models are needed for reliable effectiveness and safety evaluations of diagnostic and therapeutic applications, including medical implants safety. This paper describes the research and development performed to obtain anatomical models that meet the requirements necessary for medical implant safety assessment applications. These include implementation of quality control procedures, re-segmentation at higher resolution, more-consistent tissue assignments, enhanced surface processing and numerous anatomical refinements. Several tools were developed to enhance the functionality of the models, including discretization tools, posing tools to expand the posture space covered, and multiple morphing tools, e.g., to develop pathological models or variations of existing ones. A comprehensive tissue properties database was compiled to complement the library of models. The results are a set of anatomically independent, accurate, and detailed models with smooth, yet feature-rich and topologically conforming surfaces. The models are therefore suited for the creation of unstructured meshes, and the possible applications of the models are extended to a wider range of solvers and physics. The impact of these improvements is shown for the MRI exposure of an adult woman with an orthopedic spinal implant. Future developments include the functionalization of the models for specific physical and physiological modeling tasks.
A body area network is a radio communication protocol for short-range, low-power, and highly reliable wireless communication for use on the surface, inside, or in the peripheral proximity of the human body. Combined with various biomedical sensors, BANs enable realtime collection and monitoring of physiological signals. Therefore, it is regarded as an important technology for the treatment and prevention of chronic diseases, and health monitoring of the elderly. The IEEE 802 LAN/MAN Standards Committee approved Task Group TG15.6 in December 2007. As a result of more than four years of effort, in February 2012, TG15.6 published the first international standard for BANs, IEEE Std 802.15.6. Throughout the development of this standard, ample collaboration between the standardization group and the research community was required. In particular, understanding the radio propagation mechanisms for BANs demanded the most research effort. Technical challenges were magnified for the case of implant communication because of the impossibility of conducting in-body measurements with human subjects. Therefore, research in this field had to make use of intricate computer simulations. This article outlines some of the research that has been done to obtain accurate propagation models supporting the standardization of implant communication in BANs. Current research to enhance the channel models of IEEE Std 802.15.6 through the use of ultra wideband signals for implantable devices along with physical measurements in animals is also presented.
A multi-implant scenario is considered using insulated dipole antennas for specific locations such as the liver, heart, spleen and the kidneys where implants communicate with a pacemaker acting as a central hub. Wireless communication within human body experiences loss in the form of attenuation and absorption, and to identify these losses, the path loss is studied in this paper for an adult and child heterogeneous human model. Link performance is calculated to investigate the applicability of in-body communication. The specific absorption rate for all these locations is also studied to verify compliance with international safety guidelines.
A wireless body area network (WBAN) consists of a wireless network with devices placed close to, attached on, or implanted into the human body. Wireless communication within human body experiences loss in the form of attenuation and absorption. A path loss (PL) model is thus necessary to identify these losses in homogeneous medium which is proposed in this paper. The model is based on 3-D electromagnetic simulations and is validated with measurements. Simulations are further extended for different relative permittivity and conductivity combinations spanning a range of human tissues at 2.45 GHz, and the influence of the dielectric properties on PL is investigated and modeled. This model is valid for insulated dipole antennas separated by a distance up to 8 cm. Furthermore, PL in homogeneous medium is also compared with the path loss in heterogeneous tissues. The path loss model for homogeneous medium is the first in-body model as a function of , , and separation between antennas and can be used to design an in-body communication system.
The rapid increase in healthcare demand has seen novel developments in health monitoring technologies, such as the body area networks (BAN) paradigm. BAN technology envisions a network of continuously operating sensors which measure critical physical and physiological parameters e.g., mobility, heart rate and glucose levels. Wireless connectivity in BAN technology is key to its success as it grants portability and flexibility to the user. While radio frequency (RF) wireless technology has been successfully deployed in most BAN implementations, they consume a lot of battery power, are susceptible to electromagnetic interference and have security issues. Intrabody communication (IBC) is an alternative wireless communication technology which uses the human body as the signal propagation medium. IBC has characteristics that could naturally address the issues with RF for BAN technology. This survey examines the on-going research in this area and highlights IBC core fundamentals, current mathematical models of the human body, IBC transceiver designs, and the remaining research challenges to be addressed. IBC has exciting prospects for making BAN technologies more practical in the future.
In this paper, the interaction between the ultra wideband (UWB) antenna and human body is considered and demonstrated in the range of 0 – 30 mm above the body surface, which could be practical operation distance for the on-body antenna. Two different planar UWB antennas (loop and dipole) are used for the examinations. First, the antenna performance in free space (FS) is shown. Then, the effect of the antenna-body distance on the antenna operation is analysed in the terms of the matching, i.e., reflection coefficient S11. Measurements are carried out in the proximity of a real human body while the simulations are run by using the whole body model having a frequency-dependent behaviour. Observations are concluded to commensurate with the antenna field regions and the size of antenna’s reactive near-field was satisfied to be an important factor in the evaluation of an acceptable on-body operation. No significant differences between different antennas were observed through investigations. Both antennas perform satisfactory when the distance is high enough. The results of this study are helpful to engineers and designers evaluating antennas for the use in UWB wireless body area network (WBAN) applications.
The design and development of wearable biosensor systems for health monitoring has garnered lots of attention in the scientific community and the industry during the last years. Mainly motivated by increasing healthcare costs and propelled by recent technological advances in miniature biosensing devices, smart textiles, microelectronics, and wireless communications, the continuous advance of wearable sensor-based systems will potentially transform the future of healthcare by enabling proactive personal health management and ubiquitous monitoring of a patient's health condition. These systems can comprise various types of small physiological sensors, transmission modules and processing capabilities, and can thus facilitate low-cost wearable unobtrusive solutions for continuous all-day and any-place health, mental and activity status monitoring. This paper attempts to comprehensively review the current research and development on wearable biosensor systems for health monitoring. A variety of system implementations are compared in an approach to identify the technological shortcomings of the current state-of-the-art in wearable biosensor solutions. An emphasis is given to multiparameter physiological sensing system designs, providing reliable vital signs measurements and incorporating real-time decision support for early detection of symptoms or context awareness. In order to evaluate the maturity level of the top current achievements in wearable health-monitoring systems, a set of significant features, that best describe the functionality and the characteristics of the systems, has been selected to derive a thorough study. The aim of this survey is not to criticize, but to serve as a reference for researchers and developers in this scientific area and to provide direction for future research improvements.
This paper shows channel models on path loss and power delay profile for wireless body area networks. These models were derived from measured channel transfer functions by using a vector network analyzer. The path loss models were obtained for the frequency bands of 430, 611, 953, 2450 MHz, and UWB band. A power delay profile model was given only for the UWB band because typical symbol duration of WBAN except UWB is long enough to include delayed paths in one symbol.
Proposed is the first in-body path loss model in homogeneous human muscle tissue at 2.4 GHz for implants in the human body. This model is valid for insulated dipole antennas up to a distance of 8 cm. Excellent agreement is obtained between measurements, simulations and the models. The path loss model can be used to design an in-body communication system.
Wireless Body Area Networks (WBAN) has emerged as a key technology to provide real-time health monitoring of a patient and to diagnose and treat many life threatening diseases. WBAN operates in close vicinity to, on, or inside a human body and supports a variety of medical and non-medical applications. IEEE 802 has established a Task Group called IEEE 802.15.6 for the standardization of WBAN. The purpose of the group is to establish a communication standard optimized for low-power in-body/on-body nodes to serve a variety of medical and non-medical applications. This paper explains the most important features of the new IEEE 802.15.6 standard. The standard defines a Medium Access Control (MAC) layer supporting several Physical (PHY) layers. We briefly overview the PHY and MAC layers specifications together with the bandwidth efficiency of IEEE 802.15.6 standard. We also discuss the security paradigm of the standard.
Recent advances in microelectronics and integrated circuits, system-on-chip design, wireless communication and intelligent low-power sensors have allowed the realization of a Wireless Body Area Network (WBAN). A WBAN is a collection of low-power, miniaturized, invasive/non-invasive lightweight wireless sensor nodes that monitor the human body functions and the surrounding environment. In addition, it supports a number of innovative and interesting applications such as ubiquitous healthcare, entertainment, interactive gaming, and military applications. In this paper, the fundamental mechanisms of WBAN including architecture and topology, wireless implant communication, low-power Medium Access Control (MAC) and routing protocols are reviewed. A comprehensive study of the proposed technologies for WBAN at Physical (PHY), MAC, and Network layers is presented and many useful solutions are discussed for each layer. Finally, numerous WBAN applications are highlighted.
This pilot study in five healthy adult humans forms the pre-clinical assessment of the effect of a forced convective head cooling device on intracranial temperature, measured non-invasively by magnetic resonance spectroscopy (MRS).
After a 10 min baseline with no cooling, subjects received 30 min of head cooling followed by 30 min of head and neck cooling via a hood and neck collar delivering 14.5 degrees C air at 42.5 litre s(-1). Over baseline and at the end of both cooling periods, MRS was performed, using chemical shift imaging, to measure brain temperature simultaneously across a single slice of brain at the level of the basal ganglia. Oesophageal temperature was measured continuously using a fluoroptic thermometer.
MRS brain temperature was calculated for baseline and the last 10 min of each cooling period. The net brain temperature reduction with head cooling was 0.45 degrees C (SD 0.23 degrees C, P=0.01, 95% CI 0.17-0.74 degrees C) and with head and neck cooling was 0.37 degrees C (SD 0.30 degrees C, P=0.049, 95% CI 0.00-0.74 degrees C). The equivalent net reductions in oesophageal temperature were 0.16 degrees C (SD 0.04 degrees C) and 0.36 degrees C (SD 0.12 degrees C). Baseline-corrected brain temperature gradients from outer through intermediate to core voxels were not significant for either head cooling (P=0.43) or head and neck cooling (P=0.07), indicating that there was not a significant reduction in cooling with progressive depth into the brain.
Convective head cooling reduced MRS brain temperature and core brain was cooled.
Propagation model plays a very important role in designing wireless communication systems. Current advances in semiconductor technology has made it possible to implant a network of bio-sensors inside the human body for health monitoring purposes [C. Furse, H.K. Lai, C. Estes, A. Mahadik, A. Duncan, 1999], [C. Furse, R. Mohan, A. Jakayar, S. Karidehal, B. McCleod, S. Going, 2001], [L. Schwiebert, S.K.S. Gupta, P.S.G. Auner, G. Abrams, R. Lezzi, P. McAlister, 2002]. For wireless communication inside the human body, the tissue medium acts as a channel through which the information is sent as electromagnetic (EM) radio frequency (RF) waves. A propagation model is necessary to determine the losses involved in the form of absorption of EM wave power by the tissue. Absorption of EM waves by the tissue body, which consists of mostly saline water, accounts for a major portion of the propagation loss. In this paper we present a propagation loss model (PMBA) for homogeneous tissue bodies. We have verified the model for the frequency range of our interest (900 MHz to 3 GHz) using a 3D EM simulation software, HFSS™, and experimental measurements using saturated salt water.
A computational platform has been developed that is capable of simulating electromagnetic (EM) field interactions with neurons in complex tissue-structure environments. The platform has been tested in three case studies, namely: a) transcranial alternating current brain stimulation; b) MRI gradient coil switching induced nerve stimulation; and c) muscle activation by a neuroprosthetic implant. These applications were based on the use of a functionalized head and a whole-body model. Additionally a dedicated EM solver coupled with dynamic models of neuronal activity was also implemented. A high-resolution model of the head was developed for the analysis of EM-neuron interactions. Multimodal magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) data were acquired to guide neuron model placement and provide information on tissue anisotropy. The model, called 'MIDA', features a large number of structures, particularly those (ears, eyes, and selected deep brain structures) relevant for applications such as DBS (Deep Brain Stimulation) and neuroprosthetics. A DBS application example is also shown.
Intra-Body Communication (IBC) has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16dB after matching. A BPSK modulation scheme is also used to evaluate the Bit Error Rate (BER) improvement.
A theoretical method for analyzing the performance of wireless body sensors in terms of channel capacity and biterror- rate (BER) in the presence of slow and fast fading effects is presented. Analytical closed-form expressions for the channel capacity and BER for implant-to-implant, implant-to-bodysurface and body-surface-to-body-surface propagation scenarios are developed. Numerical results of the channel capacities and the BERs are presented utilizing realistic channel models for wireless body area networks (WBANs). The results indicated high system outage probability and degraded channel capacity caused by the complex propagation mechanisms of radio frequency signals on the surface and inside the human body. The communication links of WBANs should thus be optimized using fade mitigation techniques suitable for miniature wireless electronic devices to achieve the targeted high quality-of-service (QoS) requirements of biomedical systems. Generally, the results give an insight into the effect of the propagation channel on system performance, and may allow service providers to evaluate the technical feasibility of biomedical systems for various propagation scenarios.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been shown to reduce some of the symptoms of advanced, levodopa-responsive Parkinson's disease that are not adequately controlled with medication. However, the precise mechanism of the therapeutic action of DBS is still unclear. Stimulation-induced side effects are not uncommon and require electrical "dose" adjustments. Quantitative methods are needed to fully characterize the electric field in the deep brain region that surrounds the electrodes in order to help with adjustments and maximize the efficacy of the device. Herein we report a magnetic resonance imaging (MRI)-based head model proposed for analysis of fields generated by deep brain stimulation (DBS). The model was derived from multimodal image data at 0.5mm isotropic spatial resolution and distinguishes 142 anatomical structures, including the basal ganglia and 38 nuclei of the thalamus. Six bipolar electrode configurations (1-2, 1-3, 1-4, 2-3, 2-4, 3-4) were modeled in order to assess the effects of the inter-electrode distance of the electric field. Increasing the distance between the electrodes results in an attenuated stimulation, with up to 25% reduction in electric field amplitude delivered (2-3 vs. 1-4). The map of the deep brain structures provided a highly precise anatomical detail which is useful for the quantitative assessment of current spread around the electrode and a better evaluation of the stimulation setting for the treatment optimization.
Geographic locations of cellular base stations sometimes can be well fitted
with spatial homogeneous Poisson point processes. In this paper we make a
complementary observation: In the presence of the log-normal shadowing of
sufficiently high variance, the statistics of the propagation loss of a single
user with respect to different network stations are invariant with respect to
their geographic positioning, whether regular or not, for a wide class of
empirically homogeneous networks. Even in perfectly hexagonal case they appear
as though they were realized in a Poisson network model, i.e., form an
inhomogeneous Poisson point process on the positive half-line with a power-law
density characterized by the path-loss exponent. At the same time, the
conditional distances to the corresponding base stations become independent and
log-normally distributed, which can be seen as a decoupling between the real
and model geometry. The result applies also to Suzuki (Rayleigh-log-normal)
propagation model. We use Kolmogorov-Smirnov test to empirically study the
quality of the Poisson approximation and use it to build a linear-regression
method for the statistical estimation of the value of the path-loss exponent.
Antenna designers have come to rely on Electromagnetic (EM) simulators for accurate prediction of antenna performance prior to building and testing prototypes. Over time, several different EM simulation technologies have been developed and commercialized, each with relative strengths for certain types of antennas. This paper provides an overview of three common EM technologies: Method of Moments (MoM), Finite Element Method (FEM) and Finite Difference Time Domain (FDTD). Included are examples of how these EM technologies are applied to various antenna topologies.
Wireless Body Area Network (WBAN) is an emerging research area focuses within Mobile and Ad-hoc Network (MANET). WBAN mainly deals with the remote health observation, depending on the requirements of miniaturized wireless sensors tactfully placed on the human body. These sensors are used to monitor various important parameters related with the human health. There are number of challenging tasks for researchers to address specific requirements of WBAN related with the propagation and energy models for wireless communication on the body. This piece of work consists of two parts: propagation model for static and dynamic nodes with the human body, and proposed energy model for WBAN. Special attention is paid on the node movement issues related to the wave propagation of wireless signals around the body. Path loss of (up to 20dB) is investigated when a node moves with the body in log normal shadow fading environment. An energy model for WBAN based on the values of power received and path loss from the propagation model is also proposed in this paper.
A low profile printed magnetic loop antenna, implanted in the human tissues (i.e. skin, fat, and muscle) is presented in this paper. The antenna has been studied for the performance of a communication link between the implanted antenna and on-body or outside the body antenna. Ultra Wideband (UWB) system for communication from in-body implanted device to on-body or outside the body is one of the strong candidate for wireless medical applications. Propagation paths of Wireless Body Area Network (WBAN) can experience fading due to energy absorption, reflection, diffraction, and polarization mismatch. In order to minimize the propagation losses a well design antenna will be needed, however, at the same time antenna should be designed with respect to body tissues electrical properties. Antennas implanted in a human body must be designed with in-deep understanding of surrounding environment, keeping in mind that tissue environment is different from free space.
Biomedical telemetry permits the transmission (telemetering) of physiological signals at a distance. One of its latest developments is in the field of implantable medical devices (IMDs). Patch antennas currently are receiving significant scientific interest for integration into the implantable medical devices and radio-frequency (RF)-enabled biotelemetry, because of their high flexibility in design, conformability, and shape. The design of implantable patch antennas has gained considerable attention for dealing with issues related to biocompatibility, miniaturization, patient safety, improved quality of communication with exterior monitoring/control equipment, and insensitivity to detuning. Numerical and experimental investigations for implantable patch antennas are also highly intriguing. The objective of this paper is to provide an overview of these challenges, and discuss the ways in which they have been dealt with so far in the literature.
We demonstrated the size reduction of axial-mode helical antenna based on Co2Z hexaferrite-glass composite. Axial-mode helical antenna was employed to provide reliable communication for unmanned aerial vehicle (UAV) applications. The conventional axial-mode helical antenna uses an air core or low dielectric material, resulting in large antenna size. To increase the miniaturization factor n = (μrεr)0.5, a Co2Z hexaferrite-glass composite was used as an antenna core. The 3-dimensional finite element method (FEM) simulation was performed to design a hexaferrite helical antenna and confirm the axial-mode operation at 2.44 GHz with gain of 2.0 dBi. The designed hexaferrite helical antenna showed 82% of volume reduction and good impedance matching compared to the air-core antenna. The axial-mode hexaferrite antenna was fabricated based on the designed structure and characterized in an anechoic chamber. The maximum gain of 0.541 dBi was measured with the pitch angle of 10° at 2.39 GHz. Also, a two-element axial-mode antenna array was designed based on the miniature hexaferrite antenna to further improve antenna gain. Maximum gain of 4.5 dBi at 2.43 GHz was simulated for the antenna array. Therefore, high gain and miniature antenna can be achieved with the combination Co2Z hexaferrite-glass composite and antenna design technology.
Implantable devices have been continually anticipated as a future tool for in-body wireless communication because of their potential to replace cable connectivity with biological telemetry monitoring. This paper presents an implanted compact folded antenna of 20.3 mm × 0.8 mm × 0.8 mm that is designed to operate at one of the UHF bands (0.951-0.956 GHz). The measurement is implemented with an equivalent human phantom such as layered phantom representing the human arm. When the proposed antenna is implanted into a human arm, it has a maximum antenna gain of -23.5 dBi and wireless communication is viable because the margin exceeds 20 dB, according to link budget calculations.
Wearable and implantable wireless communication devices have in recent years gained increasing attention for medical diagnostics and therapeutics. In particular, Wireless Capsule Endoscopy (WCE) has become a popular method to visualize and diagnose the human gastrointestinal tract. Estimating the exact position of the capsule when each image is taken is a very critical issue in capsule endoscopy. Several approaches have been developed by researchers to estimate the capsule location. However, some unique challenges exist for in-body localization, such as the severe multipath issue caused by the boundaries of different organs, inconsistency of signal propagation velocity and path loss parameters inside the human body and the regulatory restrictions on using high-bandwidth or high power signals. In this paper, we propose a novel localization method based on spatial sparsity. We directly estimate the location of the capsule without going through the usual intermediate stage of first estimating time-of-arrival (TOA) or received signal strength (RSS) and then a second stage of estimating the location. We demonstrate the accuracy of the proposed method through extensive Monte Carlo simulations for RF emission signals within the required power and bandwidth range. The results show that the proposed method is effective and accurate, even in massive multipath conditions.
Transfer function analysis plays an important role in the investigation of intra-body communication (IBC). In this paper, the voltage distribution based on the quasi-static electric field modeling of human limb for galvanic coupling IBC is analyzed, transfer function of physical channel from 1 Hz to 1MHz is derived and proposed. The attenuation in transfer function shows that lower attenuation is obtained in frequency band from 20 kHz to 1 MHz. Moreover, rectangular pulse is utilized as the input to evaluate this system transfer function. The results in rectangular pulse response indicate separation of distance between transmitter and receiver is the major consideration in designing galvanic coupling IBC system. Finally, this paper reveals bit error rate (BER) under different distances for binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK) and 8PSK modulation schemes.
This paper presents the trend of physical layer designs for WBAN systems in IEEE 802.15.6 proposals. According to the technical requirement of the WBAN task group, many companies and research institutes have proposed physical layer architectures to provide fundamental technologies for the WBAN communication systems. Since there are various service scenarios for in-body or on-body applications, the physical layer proposals include UWB as well as narrowband techniques. Hence we summarize the design issues for the physical layer proposals with the category of narrowband and UWB signals. The key features of the proposals are described with the frequency bands, modulations, and other technical aspects.
Implant devices are used to measure biological pa-rameters and transmit their results to remote off-body devices. As implants are characterized by strict requirements on size, reliabil-ity and power consumption, applying the concept of cooperative communications to wireless body area networks (WBANs) offers several benefits. In this paper, we aim to minimize the power consumption of the implant device by utilizing on-body wearable devices, while providing the necessary reliability in terms of outage probability and bit error rate (BER). Taking into account realistic power considerations and wireless propagation environments based on the IEEE P802.l5 channel model, an exact theoretical analysis is conducted for evaluating several communication scenarios with respect to the position of the wearable device and the motion of the human body. The derived closed-form expressions are employed towards minimizing the required transmission power, subject to a minimum QoS requirement. In this way, the complexity and power consumption are transferred from the implant device to the on-body relay, which is an efficient approach since they can be easily replaced, in contrast to the in-body implants. Index Terms—biomedical implants, IEEE P802.l5 channel model, power consumption, reliability, wireless body area network (WBAN).
During the last years, the implant devices tend to comprise a complete wireless transceiver, enabling the remote control of the monitoring. In contrast to conventional wire-less communication systems, medical implants are characterized by much stricter limitations on size, reliability and power consumption, with the latter being of critical importance, since the replacement of the implants usually requires an invasive procedure. In this paper, taking into account a realistic wireless propagation environment based on the IEEE P802.15 channel model, we investigate the system's performance in terms of the Bit error Probability under various scenarios. The results of this work indicate that the placement of the wearable relays on the human body (e.g., hip, wrist, ankle) plays an important role for both the total power consumption and the wireless link quality. Several different scenarios are investigated, which give insight into the system requirements and its behavior under realistic wireless environments and power considerations.
Accurate prediction of specific absorption rate (SAR) for high field MRI is necessary to best exploit its potential and guarantee safe operation. To reduce the effort (time, complexity) of SAR simulations while maintaining robust results, the minimum requirements for the creation (segmentation, labeling) of human models and methods to reduce the time for SAR calculations for 7 Tesla MR-imaging are evaluated. The geometric extent of the model required for realistic head-simulations and the number of tissue types sufficient to form a reliable but simplified model of the human body are studied. Two models (male and female) of the virtual family are analyzed. Additionally, their position within the head-coil is taken into account. Furthermore, the effects of retuning the coils to different load conditions and the influence of a large bore radiofrequency-shield have been examined. The calculation time for SAR simulations in the head can be reduced by 50% without significant error for smaller model extent and simplified tissue structure outside the coil. Likewise, the model generation can be accelerated by reducing the number of tissue types. Local SAR can vary up to 14% due to position alone. This must be considered and sets a limit for SAR prediction accuracy. All these results are comparable between the two body models tested. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
A 2.5 times 1.8 cm2 medical implant communication service band antenna is combined with an electrode for body channel communication. The proposed design enables a body sensor network controller to communicate with health-care devices located on and inside a patient's body. The spiral microstrip antenna with its radiating body and ground plane placed side-by-side has the thickness of 2 mm and can be attached to human skin conveniently. The propagation loss of the body channel is measured when the proposed antenna is used as the skin interface for BCC in the 10-70-MHz band, and the results are compared with the cases of Ag/AgCl and circular dry electrodes. The equivalent-circuit model of the antenna as the electrode is also derived from the measured impedance characteristics. The LC resonance structure to drive the on-body antenna with its capacitance increased due to the skin contact reduces the power consumption of the TX buffer by >50%. The S 11-parameter of the on-body antenna, its radiation pattern, and the signal loss inside the human body are investigated.
In implanted biomedical devices, due to the presence of surrounding dissipative biological tissue, the antenna suffers poor impedance matching. This causes degradation in the performance of a wideband or ultra-wideband (UWB) implanted device. Moreover, the electrical properties of tissue change from organ to organ, and possibly from time to time. In this paper, it is shown that loading of antennas with suitable insulators can deliver broadband matching across a range of dissipative medium properties. An impedance-matched UWB antenna designed to operate inside a lossy medium, which has varying electromagnetic properties within the range expected in biological tissues, is presented. The operating bandwidth of the proposed design is 3.5-4.5 GHz, which is an interference-free subset of the unlicensed UWB band in the US. It is demonstrated that once the dielectric loading is applied, the conventional procedure for antenna design in free space can be followed. The proposed implantable small capsule-shaped slot antenna has been characterized using numerical simulations. Details of a proof-of-concept experiment are presented.
The paper introduces numerical and experimental investigations of biotelemetry radio channels and wave attenuation in human subjects with ingested wireless implants. The study covers commonly used frequencies in telemedicine applications: ultrahigh frequencies at 402 MHz, 868 MHz and the industrial, scientific and medical (ISM) band frequency at 2.4 GHz. Numerical electromagnetic analysis is applied to model in/on-body radio propagation channels and the resulted parameters demonstrated the importance of digital phantom accuracy in ccharacterization of wave absorption and attenuation with regards to organ contents, specifically for the digestion system. Path gain variations of biotelemetry radio channels, in the close vicinity of the subject, with wireless implants were measured using a near field scanner. Simulation results were verified with measurement in good agreement.
Wireless body area network for sensing and monitoring of vital signs is the one of most rapid growing wireless communication system. A key component of wireless body area network is an antenna. It must meet biocompatible and size- limit requirements. Therefore, antenna for wireless body area network faces numerous RF challenges. We used an antenna with two layers of substrate to cancel the effect of human body on antenna performance. In this paper we present an UWB antenna performance in the free space, on direct contact with human body and way out to reduce the effect of human body on antenna performance without any changes on antenna design.
We present a flexible folded slot dipole implantable antenna operating in the Industrial, Scientific, and Medical (ISM) band (2.4-2.4835 GHz) for biomedical applications. To make the designed antenna suitable for implantation, it is embedded in biocompatible Polydimethylsiloxane (PDMS). The antenna was tested by immersing it in a phantom liquid, imitating the electrical properties of the human muscle tissue. A study of the sensitivity of the antenna performance as a function of the dielectric parameters of the environment in which it is immersed was performed. Simulations and measurements in planar and bent state demonstrate that the antenna covers the complete ISM band. In addition, Specific Absorption Rate (SAR) measurements indicate that the antenna meets the required safety regulations.
A wireless body area network (WBAN) is a network, consisting of nodes that communicate wirelessly and are located on or in the body of a person. In this paper, the authors study the wave propagation using biocompatible folded slot dipole antennas within various lossy human tissues such as the muscle tissue, skin and the fat layer and obtain their path loss (PL) and specific absorption rate (SAR) by means of simulations, and fit a suitable path loss model to the propagation scenario at hand.
This paper presents hybridization approaches of the method of moments (MoMs) and the partial-element equivalent-circuit (PEEC) method in order to achieve a significant reduction of numerical complexity. The MoMs is applied as a full-wave method-only where it is necessary-to 3-D metallic scatterers such as antennas. Furthermore, the PEEC method is applied to single-layer printed circuit boards combined with an effective dielectric constant assuming an infinite dielectric in order to avoid discretization of the substrate. In the hybrid approaches of the MoMs and the PEEC method, both techniques are applied consecutively compared to a full-wave MoMs model. The validity of the hybrid approaches and the gain in numerical computation time are demonstrated by three numerical examples, which are related to electromagnetic compatibility. The results are verified by full-wave MoMs reference calculations and by a measurement.
A dynamic narrowband on-body area communications scenario is characterized with respect to link margin as a difference between system operating point, in terms of receive power, and receiver sensitivity. The characterization is based on an extensive measurement campaign near the 900 MHz ISM bands, with a number of different human subjects moving at a range of speeds in an indoor-office scenario. Key implications for operating reliability in terms of outages, meeting latency requirements, infeasibility of interleaving and limits upon packet duration are drawn from this link margin analysis pertinent to body-area-communications system design. The need for receive hardware with good receiver sensitivity is highlighted. Further to this context important second-order statistics are given, such as fade duration, as well as a novel measure: average fade magnitude. Distributions are given to accurately characterize these second order statistics. Along with link margin analysis, this modeling can be used to verify possible implementations, and help in system design.
Parallel transmission facilitates a relatively direct control of the RF transmit field. This is usually applied to improve the RF field homogeneity but might also allow a reduction of the specific absorption rate (SAR) to increase freedom in sequence design for high-field MRI. However, predicting the local SAR is challenging as it depends not only on the multi-channel drive but also on the individual patient.
The potential of RF shimming for SAR management is investigated for a 3 T body coil with eight independent transmit elements, based on Finite-Difference Time-Domain (FDTD) simulations. To address the patient-dependency of the SAR, nine human body models were generated from volunteer MR data and used in the simulations. A novel approach to RF shimming that enforces local SAR constraints is proposed.
RF shimming substantially reduced the local SAR, consistently for all volunteers. Using SAR constraints, a further SAR reduction could be achieved with only minor compromises in RF performance.
Parallel transmission can become an important tool to control and manage the local SAR in the human body. The practical use of local SAR constraints is feasible with consistent results for a variety of body models.
This work presents the design and realization procedure of small implantable antenna for biotelemetry applications. The radiator occupies a volume smaller than 3 cm3 (without its biocompatible insulation), is well matched within the Medical Implanted Communications System band and shows an adequate gain (-28.5 dB) while introduced in the appropriate equivalent body medium. The latter is a homogeneous phantom with muscle dielectric properties. A prototype has been manufactured and measurements agree with theoretical predictions. Particular attention is paid to the building requirements such as the presence of glue. Specific Absorption Rate (SAR) distribution has been computed evaluating the maximum power deliverable to the antenna in order to respect the regulated SAR limitation.
Wireless patient monitoring using wearable sensors is a promising application. This paper provides stochastic channel models for wireless body area network (WBAN) on the human body. Parameters of the channel models are extracted from measured channel transfer functions (CTFs) in a hospital room. Measured frequency bands are selected so as to include permissible bands for WBAN; ultra wideband (UWB), the industry, science and medical (ISM) bands, and wireless medical telemetry system (WMTS) bands. As channel models, both a path loss model and a power delay profile (PDP) model are considered. But, even though path loss models are derived for the all frequency bands, PDP model is only for the UWB band due to the highly frequency selectiveness of UWB channels. The parameters extracted from the measurement results are summarized for each channel model.
An unprecedented transformation in the design, deployment, and application of short-range wireless devices and services is in progress today. This trend is in line with the imminent transition from third- to fourth-generation radio systems, where heterogeneous environments are expected to prevail eventually. A key driver in this transition is the steep growth in both demand and deployment of WLANs/WPANs based on the wireless standards within the IEEE 802 suite. Today, these short-range devices and networks operate mainly standalone in indoor home and office environments or large enclosed public areas, while their integration into the wireless wide-area infrastructure is still nearly nonexistent and far from trivial. This status quo in the short-range wireless application space is about to be disrupted by novel devices and systems based on the emerging UWB radio technology with the potential to provide solutions for many of today's problems in the areas of spectrum management and radio system engineering. The approach employed by UWB radio devices is based on sharing already occupied spectrum resources by means of the overlay principle, rather than looking for still available but possibly unsuitable new bands. This novel radio technology has received legal adoption by the regulatory authorities in the United States, and efforts to achieve this status in Europe and Asia are underway. This article discusses both the application potential and technical challenges presented by UWB radio as an unconventional but promising new wireless technology.
Propagation model plays a very important role in designing wireless communication systems. Current advances in semiconductor technology has made it possible to implant a network of bio-sensors inside the human body for health monitoring purposes [12], [14], [8]. For wireless communication inside the human body, the tissue medium acts as a channel through which the information is sent as electromagnetic (EM) radio frequency (RF) waves. A propagation model is necessary to determine the losses involved in the form of absorption of EM wave power by the tissue. Absorption of EM waves by the tissue body, which consists of mostly saline water, accounts for a major portion of the propagation loss. In this paper we present a propagation loss model (PMBA) for homogeneous tissue bodies. We have verified the model for the frequency range of our interest (900MHz to 3GHz) using a 3D EM Simulation Software, HFSS TM , and experimental measurements using saturated salt water.
Body area antenna link modeling using MATLAB engine
- G Noetscher
- Y Xu
- S Makarov
G. Noetscher, Y. Xu, and S. Makarov, "Body area
antenna link modeling using MATLAB engine,"
in 35th Antenna Applications Symposium,
Monticello, IL, pp. 20-22. 2011.
UWB antenna for wireless body area network Modeling and characterization of biotelemetric radio channel from ingested implants considering organ contents
- K Y Yazdandoost
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K. Y. Yazdandoost and R. Kohno, " UWB antenna
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An Internet resource for the calculation of the dielectric properties of body tissues in the frequency range 10 Hz-100 GHz
- D Andreuccetti
- R Fossi
- C Petrucci
D. Andreuccetti, R. Fossi and C. Petrucci, "An
Internet resource for the calculation of the
dielectric properties of body tissues in the
frequency range 10 Hz-100 GHz", online
http://niremf.ifac.cnr.it/tissprop/.