Wireless Implant Communications Using the Human Body

Wireless Implant Communications Using the Human Body

Assefa K. Teshome (Victoria University, Australia), Behailu Kibret (College of Engineering and Science, Victoria University, Australia) and Daniel T. H. Lai (College of Engineering and Science, Victoria University, Australia)
Copyright: © 2018 |Pages: 16
DOI: 10.4018/978-1-5225-2255-3.ch550
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Abstract

This chapter first examines a new analytical electromagnetic model that uses galvanically coupled intrabody communication (IBC). Frequencies ranging from hundreds of kHz up to a few MHz are considered under quasi static assumptions. The model is unified in the sense that it can be applied to any part of the body (i.e., head, torso, limbs etc.). It also describes influences of tissue property and geometry of the body part. The security and low power consumption of IBC are also apparent in this model. The path loss characterisation of IBC implants shows lower values compared to their MICS counterparts. In addition, the chapter also elaborates on the use of human body as antenna. A scenario where an RF current is fed by a tiny toriodal inductor clamped around tissues in the ankle is studied. The frequency range of 1-70 MHz is considered. Theoretical results show that the system has a maximum gain of - 25 dB between 20 to 40 MHz, assuming an isotropic radiation from human body. For improved performance, mitigation techniques for losses are also discussed.
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Background: Implant Communication In The Wban Architecture

To improve accuracy and timeliness of diagnosis, and hence improve quality of life, sophisticated actuators and biosensors are emerging for various diagnostic applications; for example, glucose sensors for continuous diabetes monitoring (Heo et al., 2013). In broad terms, implant communication technique explored in literature use radio wave propagation, magnetic induction and volume conduction(Poon, 2010), (Bjorninen et al., 2012), (Yang, 2006).

For implant communication it is important that the transmitter consumes small power to conserve battery life. The implant should also be miniaturized for a minimal invasive embedding. Besides, due to sensitive nature of medical data, security is a paramount requirement of implant communication. To achieve security either the signal needs to be encrypted at the transmitter or be confined to within the body detectable by as far as an on-body receiver. In the case of MedRadio based implant, the signal is radiated outside the human body; hence, requires all security features be implemented right at the transmitter which increases the transmitter complexity. Hence, the transmitter consumes large power and is difficult to miniaturise.

Key Terms in this Chapter

Antenna: A device designed to radiate or receive electromagnetic radio waves.

Implant Communication: A communication scheme where an electrical signal is transmitted to or from an electronic device implanted inside the human body.

Galvanically Coupled IBC: A type of intra-body communication where electric current is differentially coupled to the body using the anode and cathode electrodes implanted or mounted on the surface of the human body.

Intra-Body Communication (IBC): Electric field communication using the human body as channel.

Electromagnetic Models: Analytical and/or numerical models that describe propagation of electromagnetic signals through a medium.

Wireless Body Area Network (WBAN): Signal transmission network of transmitters and receivers in, on and around the vicinity of the human body using the human body as part of communication channel.

Human Body Antenna: The usage of the human body as an antenna to transmit or receive electromagnetic radio waves.

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