Influence of animal body on ingested wireless device before and after death

Abstract

This paper measured the radiation characteristics of antennas inside the ingestible wireless devices (IWDs). Three monopole antennas were designed and put in two positions of the intestine of an adult female pig at the weight of 80 kg. The return losses of the antennas were measured when the pig was anesthetic and after euthanasia within one hour. The results demonstrate that the frequencies drift greatly from 2.78, 2.17, and 4.29 GHz at the free space into 1.42, 1.0, and 2.2 GHz when the antennas are put in the top position of the intestine of the anesthetic pig and the frequency will increase to 1.62, 1.15, and 2.85 GHz after the pig's euthanasia within one hour. The frequencies increase from 1.5, 1.03, and 2.3 GHz to 1.67, 1.13, and 2.8 GHz when the antennas are put in the bottom position of the intestine of the pig after its euthanasia within one hour. The dead body of the pig absorbed less radiation energy than the living body. Our measurement results further validate the decrease of the dielectric properties of the animal tissues after death. These differences need to be taken into account in electromagnetic modeling for simulation, and should be taken into account before the design of ingested antennas. Index Terms -Return loss, antenna, ingestible wireless device, intestine.

In Vivo Characterization of a Wireless Telemetry Module for a Capsule Endoscopy System Utilizing a Conformal Antenna

“…It is known that the transmission and radiation modes of a helix antenna can vary depending on the geometry of the helix and these effective geometry parameters in turn depend on the effective dielectric properties of the phantom material. The effective dielectric properties of the tissues have been known to change depending on the condition of the porcine [36]. The coaxial cable geometry along with the helix could have contributed for the occurrence of combination of transmission and radiation modes, thereby increasing the measured effective bandwidth of the helix antenna.…”