Antennas and Propagation of Implanted RFIDs for Pervasive Healthcare Applications

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PROPAGATION CHARACTERIZATION OF IMPLANTABLE ANTENNA AT UWB FREQUENCY – A REVIEW

A technology of wireless body area network (WBAN) was invented in order to enhance the quality of healthcare management as well as to determine faster disease prevention. However, to obtain the real-time data of images and videos from inside the human body, an implantable device is required. Currently, the Medical Implant Communication System (MICS) is used, but, this system has limited data rate which is a narrow-band of 402 – 405 MHz. Thus, this study on Ultra Wideband (UWB) for implanted device is conducted as UWB offers a wide transmission bandwidth as well as high data rate. Knowledge of radio wave propagation behaviour inside human body is needed to perform the implantation. Past researches related to this topic are limited and those conducted focused only on the human torso. This paper aims to provide a better understanding on the characteristics of radio wave propagation inside the human body by using an implantable device at UWB frequency. It is also hoped that this study could be used as reference for future research on this subject

Propagation characterization of implantable antenna at UWB frequency – a review

A technology of wireless body area network (WBAN) was invented in order to enhance the quality of healthcare management as well as to determine faster disease prevention. However, to obtain the real-time data of images and videos from inside the human body, an implantable device is required. Currently, the Medical Implant Communication System (MICS) is used, but, this system has limited data rate which is a narrow-band of 402 – 405 MHz. Thus, this study on Ultra Wideband (UWB) for implanted device is conducted as UWB offers a wide transmission bandwidth as well as high data rate. Knowledge of radio wave propagation behaviour inside human body is needed to perform the implantation. Past researches related to this topic are limited and those conducted focused only on the human torso. This paper aims to provide a better understanding on the characteristics of radio wave propagation inside the human body by using an implantable device at UWB frequency. It is also hoped that this study could be used as reference for future research on this subject

Design and characterization of a three material anatomical bone phantom for implanted antenna applications

This work presents the development and testing of a three layer anatomical human body phantom suitable for microwave applications. The proposed phantom consisted of bone marrow, bone cortical and muscle layers. The ingredients used for each tissue along with the calculation of the mean square error of the dielectric properties showed good agreement with the dielectric properties of real life tissues and the IEEE SAR measurement standard for tissue mimicking phantoms. The geometrical characteristics of the bone layer can be adjusted to fit the geometry of any desired bone in the human body. The suitability of the phantom has been tested using an implanted antennas application, which has yielded comparable simulation and measurement results

Wearable Quarter-Wave Folded Microstrip Antenna for Passive UHF RFID Applications

A wearable low-profile inset-fed quarter-wave folded microstrip patch antenna for noninvasive activity monitoring of elderly is presented. The proposed antenna is embedded with a sensor-enabled passive radio-frequency identification (RFID) tag operating in the ultra-high frequency (UHF) industrial-scientific-medical (ISM) band around 900 MHz. The device exhibits a low and narrow profile based on a planar folded quarter-wave length patch structure and is integrated on a flexible substrate to maximise comfort to the wearer. An extended ground plane made from silver fabric successfully minimises the impact of the human body on the antenna performance. Measurements on a prototype demonstrate a reflection coefficient (S₁₁) of −30 dB at resonance and a −10 dB bandwidth from 920 MHz to 926 MHz. Simulation results predict a maximum gain of 2.8 dBi. This is confirmed by tag measurements where a 4-meter read range is achieved using a transmit power of 30 dBm, for the case where the passive wearable tag antenna is mounted on a body in a practical setting. This represents an almost 40% increase in read range over an existing dipole antenna placed over a 10 mm isolator layer on a human subject.Thomas Kaufmann, Damith C. Ranasinghe, Ming Zhou, and Christophe Fumeau

A Simple Folded Dipole Antenna for Medical Implant Communications at 900 MHz Band

Abstract -Nowadays, implanted medical devices that are using inductive coupling for communication, cannot be used for transmitting medical data in several meters range. This triggers us to study about implantable device systems in order for communications is enabled to be longer range by transmitting wirelessly electromagnetic signal. In this system, the external devices such as home monitoring device or portable equipment will provide the patient more mobility, and the patient or the health care provider could benefit from timely and ease of access to important patient medical information via a networked connection. Due to such advantages, small antennas for implantable devices are very important components in monitoring systems to provide wirelessly communication between a patient and an access point. This paper proposes a simple structure of a folded dipole antenna for an implantable device aimed at wireless patient monitoring applications. The implantable device is assumed to be used with a syringe injection, so the device can be simply embedded into the human body. The antenna is operated in UHF band 924 MHz, which is band of Indonesian frequency allocation for RFID applications. The antenna is small enough in this band with good performances such as S parameter, impedance bandwidth, radiation pattern and gain. The antenna has enough gain for more than 10m range communication with 250 MHz bandwidth (VSWR 1.5)

Implanted Antennas for Biomedical Applications

Body-Centric Wireless Communication (BCWC) is a central topic in the development of healthcare and biomedical technologies. Increasing healthcare quality, in addition to the continuous miniaturisation of sensors and the advancement in wearable electronics, embedded software, digital signal processing and biomedical technologies, has led to a new era of biomedical devices and increases possibility of continuous monitoring, diagnostic and/or treatment of many diseases. However, the major difference between BCWC, particularly implantable devices, and conventional wireless systems is the radio channel over which the communication takes place. The human body is a hostile environment from a radio propagation perspective. This environment is a highly lossy and has a high effect on the antenna elements, the radio channel parameters and, hence a dramatic drop in the implanted antenna performance. This thesis focuses on how to improve the gain of implanted antennas. In order to improve the gain and performance of implanted antennas, this thesis uses a combination of experimental and electromagnetic numerical investigations. Extensive simulation and experimental investigations are carried out to study the effects of various external elements on the performance improvement of implanted antennas. The thesis also shows the design, characterisation, simulation and measurements of four different antennas to work at ISM band and seventeen different scenarios for body wireless communication. A 3- layer (skin, fat and muscle) and a liquid homogenise phantom were used for human body modelling in both simulation and measurements. The results shows that a length of printed line and a grid can be used on top of the human skin in order enhance the performance of the implanted antennas. Moreover, a ring and a hemispherical lens can be used externally in order to enhance the performance of the implanted antenna. This approach yields a significant improvement in the antenna gain and reduces the specific absorption rate (SAR) in most cases and the obtained gain varies between 2 dB and 8 dB