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Body Area Network (BAN) is a network of wearable sensor nodes placed on or implanted inside the human body. BAN plays an important role in the mobile health care, military training, consumer electronics and others. Usually, the BAN consists of the wearable and implanted sensor nodes which acquire, analyze and process all kinds of physiological parameters. An important issue in the development of the BAN prototype is the choice of physical layer and the communication protocol. Although often used in biomedical applications, standard communication protocols like Bluetooth, WLAN, RFID, ZigBee, and IrDA, are optimized for other purposes: WLAN for data transfer, Bluetooth for voice transmission, RFID for identification and tracking, and ZigBee for industrial applications. Data rate of WLAN and Bluetooth communication modules is fast enough for biomedical applications, but they emit high levels of EMF radiation, which can lead to tissue overheating and irritation. High transmitted power also requires frequent replacement of batteries, which is undesirable in the case of implanted sensors. ZigBee and RFID modules have lower consumption, but their achievable data rates are insufficient for biomedical applications. IrDA modules demand a direct line of sight to realize a successful communication. Common to all of these standards except to IrDA is that they are designed for communication at a distance of several tens of meters, so they inherently generate excessive power which affects the practical system usability in long-term monitoring applications. Also, they are unsuitable for a body area network from the viewpoint of security and difficulty of implantable antenna design. As an optimal wireless communication method in the vicinity of the human body, a new emerging transmission technique called intrabody communication (IBC) is proposed. Since the human body is a rather good conductive medium for the electric signals, IBC employs the human body as the transmission medium for connecting different electronic devices on, inside or near the body. In IBC the human body becomes an integral component of the electric signal transmission path, external electromagnetic noise has little influence on the signal, and abundant cables which are often used in health care monitoring are no longer needed. Moreover, high conductivity of human body compared to the surrounding environment implies the IBC as a power-saving method, capable of operating on only several milliwatts of power. The intrabody communication range is limited to the close proximity of the human body, so the receiver unit is always placed at the short distance from the transmitter unit (maximum possible distance is the subject’s height) and the security is not a problem. Two main types of intrabody communication are capacitive coupling and galvanic coupling. In the capacitive coupling approach, the induced electrical signal is controlled by an electric potential and the signal return path from the transmitter to the receiver ground electrodes is closed through the environment. It is suitable for the BAN sensors situated on the human body. In the galvanic coupling approach, the induced signal is controlled by an alternating current flowing through the human body and all the electrodes must be in direct contact with the subject. The signal is coupled to the human body via a pair of transmitter electrodes and the potential is detected differentially by the receiver electrodes of another BAN node. The galvanic type IBC is especially suitable for the sensor implanted in the human body.
Short description of the task performed by Croatian partner
The Chinese organization, Key Laboratory of Medical Instrumentation & Pharmaceutical Technology of Fuzhou University is currently focused on the galvanic coupling IBC. They proposed a mathematical model which represents a human forearm as a homogeneous multilayer cylinder. The model solves the IBC problem analytically, and is used for determination of the potential and current density distribution mechanisms and attenuation characteristic of the electric signal propagation within the human forearm. Also, they developed a set of transceivers for clinical trial based on the FPGA, as a part of the multichannel galvanic IBC system for medical health care. In this project, the Chinese partners plan to concentrate on the advancement of the galvanic IBC network protocol for implanted sensor nodes. The Croatian partner, Faculty of Electrical Engineering at the University of Zagreb, is focused on the capacitive coupling IBC. They developed a wireless EMG monitoring system design based on intrabody communication and tested it in vivo using the deterministic signals for different electrode arrangements. This EMG monitoring system is used for muscle fatigue monitoring, which is of special importance in kinesiology and rehabilitation. Currently they are investigating characteristics of the capacitive intrabody communication channel and developing a human body model for capacitive intrabody communication. In this project the cooperation between the Chinese and Croatian partners will focus on the mutual exchange of knowledge and experience in development platforms and modeling techniques. We will compare our problems and issues in hardware and modeling, and build a common base of knowledge, ideas and questions which arise in IBC application research and development. As an outcome of our cooperation, the competitiveness and excellence of both groups in the field of the IBC will improve. Furthermore, this project will lay the path towards more specific and application-oriented research project in the future, and foster the cooperation between the researchers in Croatia and China.
Ovo web sjedište koristi tehnologiju "kolačića" (eng. cookie) da bi se korisnicima prikazao dinamičan i personaliziran sadržaj, te su oni nužni za ispravan rad. Ako nastavite pregledavati ove stranice, kolačići će biti korišteni u suradnji s vašim preglednikom Weba.
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