Proposal and Evaluation of Intra-body Sensing via Sheet Medium Takashi Matsuda, Bing Zhang, Keren Li National Institute of Information and Communications Technology 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto, 619-0288, Japan Email: {matsuda, zhang, keren}@nict.go.jp Peter Davis Telecognix Corporation 58-13 Yoshida Shimooji-cho, Sakyo-ku, Kyoto, Japan Email: davis@telecognix.com Kiyotaka Sasagawa, Jun Ohta Graduate School of Materials Science, Nara Institute of Science and Technology 8916-5 Takayama, Ikoma, Nara, Japan Email: {sasagawa,ohta}@ms.naist.jp Abstract—In recent years, Intra-Body Communication (IBC) has attracted attention as a key new technique for health monitoring. It is expected that health monitoring can be improved by embedding sensors inside of the body. Then, the technology for communication between embedded sensors and monitoring systems outside of the body becomes important. Wireless com- munication is preferred to avoid the invasiveness, inflexibility and complexity of wired sensors. In this paper, we propose a new approach to communication with intra-body sensors using a sheet medium. In the proposed intra-body sensing system, electromagnetic signals can be easily and efficiently transmitted to or received from embedded sensors just by placing the sheet medium on the body. Simulation and experimental results show that the proposed system is effective, compared with the use of an electrode insert into the surface of the body rather than the sheet medium. I. I NTRODUCTION Body area networks (BAN) consist of wireless communi- cation between multiple miniature body sensors and a single body central unit worn on the human body [1]. BAN could allow inexpensive and continuous health monitoring with real- time updates of medical records. Intra-body communication (IBC) is one of the proposed approaches to realize the BAN. IBC uses the human body as a transmission medium. Currently, a number of research groups have proposed solutions for IBC. One approach using low frequencies 100- 400kHz is the IBCOM (Intra-Brain Communication) micro- system proposed by Al-Asmouny et al. [2]. IBCOM is a wireless signal transmission method that uses the brain itself as a conductive medium to transmit data and commands between neural implants. Ruiz et al. investigated the propa- gation characteristics of the human body as a conductor of radio frequency signals and evaluated five digital modulation schemes for IBC [3]. Yuan et al. proposed a model mixed with finite-element-method and circuits to analyze the IBC channel at high frequency,and also measured body channel characteristics [4][5]. This work was aimed at achieving a high data rate of a few Mbps that can be used to send small image sensing data. Some works have proposed using wireless intra-body trans- missions to deliver power as well as data from outside the Sheet Body Sensor chip Base station Fig. 1. Proposed scheme for intra-body sensing using a sheet medium as an interface for IBC. body to sensors implanted inside the body. Sun et al. proposed a pad for data transmission and power supply [6]. The pad is attached to the skin with adhesive similar to an ECG foam pad and conforms to the curvature of the body interface. The pad uses an array of electrodes or coils for antenna. Electrodes are used for so-called ”volume conduction” at low frequencies. Planar coils are used instead of electrodes for radio frequency transmission. Recently it was shown by Sasagawa et al. [7] that image sig- nals could be transmitted through brain material. By inserting electrodes into a mouse brain, the transmission efficiency is drastically increased. An AM signal modulated with the image data from an implantable image sensor [8] was launched into the brain and the received signal was demodulated. The data was successfully transmitted through the brain and the image was reproduced. In this work, we propose a new approach which uses a sheet- shaped medium as an interface for IBC (Fig. 1). Moreover, we evaluate our proposed approach by fundamental simulation and measurements. The sheet medium composes of three layers and an electromagnetic wave can be confined within the sheet medium [9]. By placing the sheet medium on the surface of a human body, it is possible to transmit data and power efficiently between sensors embedded inside the body and an outside communication terminal. We use the sheet medium 978-1-4673-1786-3/12/$31.00 ©2012 IEEE