Electromagnetic radiation from ingested sources in the human intestine

Experimental Study of Radiation Efficiency from an Ingested Source inside a Human Body Model^*

“…The porcine tissue curve lies between the water curve and saline curve, and it shows a slight drop at 500MHz. This agrees with Chirwa et al [10] that attenuation of human body was slightly lowered at frequency of 400-900MHz.…”

“…Although most of the biotelemetry devices chose 434MHz as the wireless link, this experimental result shows that 915MHz and 2.45GHz are also feasible for implanted or ingestible telemetry devices. Typical low range telemetry devices emits radiation power of less than a few milliwatts or dBm [6]- [7], [10], the body tissue specific absorption rate (SAR) are well below the IEEE safety limit of 0.4Wkg-1 [25]. At the receiving end outside the body, a typical receiver has operational sensitivity of -80 to -110dBm [7], [9].…”

“…Because of the high water content of body tissue, it is found that the absorption of electromagnetic power increases with frequency [8]- [9]. Chirwa et al [10] found that at frequency above 1GHz, the radiation field falls rapidly, which means the radiation transmission becomes less ineffective, and may not be suitable to use. A lot of research has been done to determine the electrical properties of individual body tissue, such as blood, muscle, fat and skin [11]- [14].…”

“…Although quite a few investigation has been done to determine the effect of human body on radiated field, almost all of these studies have been based on external sources [9], [15]- [18]. Until recently, implanted source has been studied in realistic human models [10], [15]. The study performed by Chirwa et al [10] used a FDTD mesh of a human subject, which was created using digitized data in the Visible Human Project [19], to simulate the effect of human body of an ingested source positioned at different location in the GI tract from 150MHz to 1.2GHz.…”

“…Until recently, implanted source has been studied in realistic human models [10], [15]. The study performed by Chirwa et al [10] used a FDTD mesh of a human subject, which was created using digitized data in the Visible Human Project [19], to simulate the effect of human body of an ingested source positioned at different location in the GI tract from 150MHz to 1.2GHz. Although this range covers the two ISM bands: 434MHz and 915MHz, these bands are not well developed for digital video transmission.…”