Remote diagnostics and monitoring using microwave technique – improving healthcare in rural areas and in exceptional situations

Interests towards wireless portable medical diagnostics and monitoring systems, which could be used outside hospital e.g. during pandemic or catastrophic situations, have increased recently. Additionally, portable monitoring solutions could partially address widely recognized challenges related to healthcare equality in rural areas. Microwave based sensing has recently been recognized as emerging technology for portable medical monitoring and diagnostics devices since they may enable development of safe, reliable, and low-cost solutions for future’s telemedicine. The aim of this paper is to present the basic idea of microwave -based medical monitoring and discuss its possibilities, advantages, and challenges. In particular, we show that microwaves could be exploited in three pre-diagnostics applications: 1) Detection of abnormalities in the brain with a helmet type of monitoring device, 2) Detection of breast cancer with a self-monitoring vest, 3) Detection of blood clots in leg with an antenna band. The technique is based on detecting differences in radio channel responses caused by the abnormalities having different dielectric properties than the surrounding tissues. Our results of realistic simulations and experimental measurements show that even small-sized abnormalities, e.g. tumors, can change channel characteristics in detectable level

Measurement of Cerebral Circulation in Human

In this chapter, we review state-of-the-art non-invasive techniques to monitor and study cerebral circulation in humans. The measurement methods can be divided into two categories: direct and indirect methods. Direct methods are mostly based on using contrast agents delivered to blood circulation. Clinically used direct methods include single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI) with contrast agents, xenon computed tomography (CT), and arterial spin labeling (ASL) MRI. Indirect techniques are based on measuring physiological parameters reflecting cerebral perfusion. The most commonly used indirect methods are near-infrared spectroscopy (NIRS), transcranial Doppler ultrasound (TCD), and phase-contrast MRI. In recent years, few more techniques have been intensively developed, such as diffuse correlation spectroscopy (DCS) and microwave-based techniques, which are still emerging as methods for cerebral circulation monitoring. In addition, methods combining different modalities are discussed and, as a summary, the presented techniques and their benefits for cerebral circulation will be compared

UWB in-body propagation and radio channel characteristics for wireless body area network applications

Abstract Recently, interest in medical and health monitoring systems has increased significantly, since these have the potential to address some of the challenges related to the aging population. Furthermore, medical monitoring enhances diagnosis and medical treatments in hospitals. New self and remote diagnosis and monitoring solutions are being developed and implemented constantly. Smooth design of monitoring devices requires deep knowledge of off-body, on-body, and in-body propagation. This thesis presents studies on in-body propagation for different wireless body area network (WBAN) applications. The main focuses are on 1) survey of the electromagnetic (EM) simulation techniques used in WBAN applications, 2) in-body propagation in the human chest area, and 3) in-body propagation in the human abdomen area. The study is carried out using radio channel measurements, finite integration technique -based channel simulations, as well as propagation path calculations. Part 2 involves studies on the impact that medical implants, which contain highly conductive materials, may have impact on channel characteristics. Sternotomy wires and an aortic valve implant are considered as example cases. This knowledge is useful for the design of monitoring devices in which the antennas are located on the chest area, especially close to the sternum. Part 3 shows how signal propagates inside the abdomen preferring the tissues which are easier for propagation due to their dielectric properties. This knowledge is useful for abdominal monitoring system design, especially antenna location design, for instance in capsule endoscopy. Part 3 also involves studies of the channel evaluations between the receiving on-body antenna and the capsule endoscope in different parts of the intestine area. Human voxels with different sizes and body constitutions are used in this study. In general, the results presented in this thesis provide new information on the propagation within the tissues, which is useful for designing monitoring devices for different WBAN applications.Tiivistelmä Kiinnostus lääketieteen ja terveyden monitorointijärjestelmiin on kasvanut, koska ne voivat osaltaan vastata ikääntyvän väestön tuomiin terveydenhuollon haasteisiin. Monitorointijärjestelmät voivat myös nopeuttaa diagnoosin saamista sekä tehostaa hoitoja sairaaloissa. Uusia omatoimi- ja etämonitorointiratkaisuja kehitetään jatkuvasti. Monitorilaitteiden suunnittelu vaatii syvällistä tietoa radiokanavan ominaisuuksista sekä siitä, miten signaali etenee kehosta ulospäin sekä kehon pinnalla ja sisällä. Väitöskirja esittää tutkimustuloksia kehon sisällä tapahtuvasta signaalin etenemisestä erilaisissa langattomien kehoverkkojen sovelluksissa. Tutkimuksen pääkohtia ovat 1) katsauksen tekeminen sähkömagneettisten simulaa¬tiotekniikoiden käytöstä, 2) ihmisen rintakehän kudoksissa tapahtuva signaalin ete¬neminen sekä 3) vatsa-alueen kudoksissa tapahtuva signaalin eteneminen. Tutki¬mus tehdään radiokanavamittauksilla, rajattuun integraalitekniikkaan perustuvilla simulaatioilla sekä laskemalla signaalin etenemispolkuja. Tutkimuksen osa 2 sisältää tuloksia siitä, miten johtavia materiaaleja sisältävät lääketieteelliset implantit voivat vaikuttaa radiokanavan ominaisuuksiin. Rintalastan sulkemisessa käytettävät rintalastalangat sekä aorttaläppäimplantti ovat esimerkkitapauksina. Tämä tieto on hyödyllistä suunnitellessa monitorointilaitteita, joissa antennit on sijoitettu rintakehän alueelle. Tutkimuksen osassa 3 esitetään, kuinka signaali etenee vatsa-alueen kudoksissa. Tämä tieto on hyödyllinen, kun suunnitellaan vatsa-alueen monitorointijärjestelmiä ja erityisesti antennien sijainteja, kuten kapseliendoskopiassa. Osassa 3 tutkitaan radiokanavaa kapseliendoskoopin ja kehon päällä olevan antennin välillä eri puolilla suolistoa erilaisilla ihmiskehomalleilla. Väitöskirjassa esitetyt tulokset tuovat uutta tietoa signaalin etenemisestä kudoksissa, mitä voidaan hyödyntää monitorointilaitesuunnittelussa

An overview of the electromagnetic simulation-based channel modeling techniques for wireless body area network applications

Abstract Electromagnetic simulation-based channel modeling is presently considered as a promising option for wireless body area network (WBAN) channel modeling. The benefits of simulation-based channel modeling are obvious: realistic channel characteristics for required environments and situations are provided flexibly and cheaply. In addition, the use of simulation-based channel modeling may overcome several challenges related to the use of measurement data, such as uncertainties and inaccuracies due to cabling, unintentional changes in the position of the test person or the antennas and so on. There are several numerical methods suitable for simulation based-channel modeling, both full-wave and an asymptotic solutions. The choice of the numerical approach depends on the nature of the communication links of the wireless body network being considered. This paper presents a general overview, including recent progress, of the electromagnetic simulation-based WBAN channel modeling techniques. Advantages, disadvantages, and the most appropriate applications are described. Furthermore, the features of the different techniques are compared

Radio channel study for colon capsule endoscopy with low-band UWB multiple antenna system

Abstract This paper presents a study of the radio channel characteristics between a colon capsule endoscope and a multiple on-body antenna system in ultra wideband wireless body area networks (UWB-WBAN). The main aim is to study the variation of the channel characteristics for the on-body antennas in different capsule locations throughout the whole colon area. The study is conducted with CST Studio Suite simulations and one of its anatomical voxel models. A simplified capsule model and directive on-body antennas designed for low-band UWB in-body communications are used. It is found that five of this type directive on-body antennas provide sufficient coverage over the whole colon are even in the most challenging capsule locations

A preliminary study of on/off-body propagation channels for brain telemetry using a flexible wearable antenna

Abstract Flexible electronics are envisioned to play a major role in future wearable medical devices. An important component of this technology is flexible antennas. This paper presents a preliminary study of on-body and off-body propagation channels in Body Area Networks (BAN) using a small Ultra WideBand (UWB) flexible wearable antenna. The research is carried out with physical measurements in an anechoic chamber and a small laboratory room. The on-body measurements include propagation channels between two wearable devices placed on the head and various locations on the arm (i.e., shoulder to wrist). The off-body measurements cover propagation channels between a head-mounted device and an external device placed at various distances from the body. The wearable devices in these measurements use a small flexible antenna that can easily conform to the surface of the body. The measurements are conducted to better understand and characterize the wireless communication channels in applications such as brain monitoring or brain computer interface. The measurement results show that the UWB flexible antenna presented here performs well for both on-body and off-body communication channels

Simulation and measurement data-based study on fat as propagation medium in WBAN abdominal implant communication systems

Abstract This paper presents comprehensive study on fat as propagation medium in abdominal implant communication system at low ultrawideband (UWB) frequency range 3.75—4.25 GHz. The main aim is to investigate how signal propagates through visceral and subcutaneous fat layers and how that information can be exploited in implant communication systems. The study is conducted using different methods: electromagnetic simulations, power flow analysis, propagation path calculations and radio channel measurements with animal meat pieces. Simulations are conducted using layer models and anatomical voxel models having different sizes. Results of channel simulations are verified with propagation path calculations. Power flow analysis on cross-cuts of the voxel models is conducted to investigate how the signal propagates inside the tissues. Furthermore, measurements using different animal meat pieces are performed to evaluate the impact of fat constitution on channel characteristics. It is found that similar tendency on fat propagation is seen in the evaluations with different methods. It is also observed that channel attenuation depends not only on the types and thicknesses of the tissues between transmitter and receiver antennas, but also how the tissues, especially fat, is located between the antennas. Channel attenuation difference between different voxels is maximum 14 dB in the studied antenna locations. Furthermore, propagation channel is evaluated with measurements using pork meat having different fat and muscle constitutions. It is found that antenna location respect to fat layers has clear impact on the channel strength although the fat tissue is not directly above the in-body antenna. The difference is noted to be 3–15 dB especially on the side peaks of channel impulse response. The knowledge on fat as a propagation medium is crucial when designing medical monitoring or implant communication systems. Location of antennas/sensor nodes for the monitoring devices can be established so that propagation through fat layer can be exploited

Remote diagnostics and monitoring using microwave technique:improving healthcare in rural areas and in exceptional situations

Abstract Interests towards wireless portable medical diagnostics and monitoring systems, which could be used outside hospital e.g. during pandemic or catastrophic situations, have increased recently. Additionally, portable monitoring solutions could partially address widely recognized challenges related to healthcare equality in rural areas. Microwave based sensing has recently been recognized as emerging technology for portable medical monitoring and diagnostics devices since they may enable development of safe, reliable, and low-cost solutions for future’s telemedicine. The aim of this paper is to present the basic idea of microwave -based medical monitoring and discuss its possibilities, advantages, and challenges. In particular, we show that microwaves could be exploited in three pre-diagnostics applications: 1) Detection of abnormalities in the brain with a helmet type of monitoring device, 2) Detection of breast cancer with a self-monitoring vest, 3) Detection of blood clots in leg with an antenna band. The technique is based on detecting differences in radio channel responses caused by the abnormalities having different dielectric properties than the surrounding tissues. Our results of realistic simulations and experimental measurements show that even small-sized abnormalities, e.g. tumors, can change channel characteristics in detectable level

Propagation study of UWB capsule endoscope with multiple on-body antennas

Abstract This paper presents a study of the radio channel characteristics between a capsule endoscopy and a multi on-body antenna system on ultra wideband wireless body area networks (UWB-WBAN). Multiple on-body antennas are required to provide reliable communication link between the capsule and the on-body device, but also essential for capsule localization. The main aim is to study the variation of the frequency and time domain channel characteristics for the selected on-body antennas in different capsule locations, including the most challenging capsule locations deep inside the tissues or far away from most of the antennas. This study also evaluates whether five of selected type directive on-body antennas is enough to cover the intestine area thoroughly. The study is conducted with CST Studio Suite simulations and one of its anatomical voxel models. A simplified capsule model and a directive on-body antenna designed for low-band UWB in-body communications are used in this study. It is found that five of this type directive on-body antennas provide sufficient coverage over the intestine area even in the most challenging capsule locations. In certain capsule locations, the variation between the channel attenuations can be significant, over 40 dB within the frequency range of interest, if the capsule is located deep inside the tissues without smooth access to outer fat layer through which the signal could travel easily to different on-body antennas. Instead, if the capsule is located close to the subcutaneous fat layer, the channel attenuation is moderate even for the antennas which are located far from the capsule

On the UWB in-body propagation measurements using pork meat

Abstract This paper presents a study on the in-body propagation using pork meat at the lower ultrawideband (UWB) frequency band 3.74—4.25 GHz of the wireless body area network (WBAN) standard 802.15.6. Pork meat in terms of the dielectric properties is one of the most similar to human tissues and thus is commonly used in in-body propagation studies. Nevertheless, there are differences in the dielectric properties, creating some differences also in the radio propagation. The first objective of this paper is to investigate by simulations the propagation differences between human and pork tissue layer models. The simulations results show clear differences between the channel characteristics obtained using a human tissues and pork tissues: within the frequency range of interest, the path loss with pork meat can be up to 5 dB less than with the human meat. The second objective of this paper is to study, by measurements, the in-body channel characteristics using different types of pork meat piece having different fat and muscle compositions. It was found that path loss is clearly higher with the pork meat having separate skin, fat, and muscle layers compared to the pork meat having interlaced fat and muscle layers. Furthermore, the third objective of this paper is to study the impact of the meat temperature on the measured channel characteristics by comparing the channels obtained with the meat at the temperatures of 12 °C and at 37 °C. Also, in this case clear differences were observed in path loss: within the frequency range of interest, the path loss was maximum 5 dB lower with meat at 37 °C than with a colder meat. The results presented in this paper provide useful information and relevant aspects for the in-body propagation studies conducted with pork meat