Radiation from ingested wireless devices in biomedical telemetry bands

Abstract

Glasgow ePrints Service http://eprints.gla.ac.uk 60" of arc with a radius of 51 and a height 1OA with A= 1 m. A vertical dipole is placed at a distance of 101 from the centre of the cylinder. Fig. 1 shows the interpolated values for the amplitude and the phase of the current on the cylinder. The difference between these values and the exact ones are shown in Fig. 2. As shown in Fig. 2 the interpolation error is negligible. The maximum relative errors in this case are 2.0 x IOp4 for the amplitude and 4.0 x IO-' for the phase.Fig. 1 Interpolated amplitude and phase of current induced by dipole on a section of cylinder with 60" of arc a Amplitude b Phase 0 02 6 4 0 4 02 4 0 4 1 0 P z 2 0 -2 1 0 0 1 0 Fig. 2 Error of interpolated amplitude and phase functions for current induced by dipole on a section of cylinder with 60" of arc a Amplitude functions b Phase functions Conclusions:A new method to represent the induced current in an accurate and efficient way has been presented. The method is based on the interpolation of the amplitude and phase by means of Btzier surfaces. An example has been shown to prove the potential of the method to represent the current with a negligible error using a low amount of sample points. This method can be used to analyse large problems by rigorous methods, or to obtain higher-order reflections in an iterative way by using asymptotic techniques. Acknowledgment: This work has been supported in part by theReferences 1 CHEW, wc , JIN, J , MICHIELSSEN, E and SONG, J (Eds.): 'Fast and efficient algorithms in computational electromagnetics' (Artech House, 2001) 2 CATEDRA, M.F., PEREZ, J., SAEZ DEADANA, E, and GUTIERREZ, 0.: 'Efficient ray-tracing techniques for 3D analysis of propagation in mobile communications. Application to picocell and microcell scenarios',The performance of wireless devices, using electrically small antennae, in the human intestine is investigated using the finite difference time domain method in recommended biomedical device telemetry bands. The radiation field intensity was found to depend on position but more strongly on frequency, with a transmission peak at 650 MHz. Introduction:There is an increasing number of applications for wireless devices designed for use close to or inside the human body. The design of such devices poses many problems, not least of which is the effect of the environment on radio signals. In this Letter we consider the effect of the human body on the propagation of radio signals from a wireless ingested diagnostic device in the gastrointestinal tract (GIT), in the 150 MHz to 1.2 GHz range, encompassing several international medical telemetry bands (pan-European allocation [I] and the US Federal Communications Commission allocationsregulations S5.150, US209 and US350).

Implantable and ingestible medical devices with wireless telemetry functionalities: A review of current status and challenges

“…Results were attributed to the authors' choice of keeping the antennas' physical dimensions identical, and modifying their effective size. Studies for ingestible MDs have demonstrated adequate communication to take place between 600 and 1000 MHz [Chirwa et al, ], with maximum radiation occurring between 450 and 900 MHz [Chirwa et al, ], and a peak in the transmitted power being identified at approximately 650 MHz [Chirwa et al, ]. Furthermore, selection of operation frequency is directly related to bit rate: higher operation frequencies allow for an increase in bandwidth and enable higher bit rates, which are favorable for high data rate applications, such as the real‐time video transmission of ingestible MDs.…”

“…For the majority of positions, vertically polarized radiation has been found to attenuate more than horizontal radiation [Chirwa et al, ], and intensity of the electric field in the anterior of the human body has been shown to be, generally, higher than that in the posterior [Xu et al, ]. In Chirwa et al [], the radiated field was found to be predominantly strongest in the same horizontal transverse plane as the source, and in the direction that was on the line from the source to the nearest body surface. Therefore, the optimum location for a receiver antenna would be an anterior location slightly to the left of the abdomen (as the small intestine does not extend so much to the right due to the presence of the colon).…”

Review of the Wireless Capsule Transmitting and Receiving Antennas

“…So, with www.intechopen.com the change from free space to body materials, dielectric constant changes from 1 to 56 and conductivity changes from 0 to 0.8. What's more, to detect the transmitted signal independent of transmitter a position, the antenna is required the omni-directional radiation pattern (Kim & Rahmat-Samii, 2004;Chirwa et al, 2003). To investigate the characteristics of antennas for capsule endoscope, the human body is considered as an averaged homogeneous medium as described by the Federal Communications Commission (FCC) and measured using a human phantom (Kwak et al, 2005;Haga et al, 2009).…”

Experiment study of transmission characteristics through conducting human body equivalent liquid

“…Thus, several researchers have been studying high efficiency antennas for capsule endoscopes [2,3,4]. Generally, the maximum size of an ingestible capsule endoscope is a length of 20 mm and a diameter of 10 mm [1].…”