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

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 pigpsilas 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.