In-Body to On-Body Ultrawideband Propagation Model Derived From Measurements in Living Animals

Abstract

Abstract-Ultra wideband (UWB) radio technology for wireless implants has gained significant attention. UWB enables the fabrication of faster and smaller transceivers with ultra low power consumption, which may be integrated into more sophisticated implantable biomedical sensors and actuators. Nevertheless, the large path loss suffered by UWB signals propagating through inhomogeneous layers of biological tissues is a major hindering factor. For the optimal design of implantable transceivers, the accurate characterization of the UWB radio propagation in living biological tissues is indispensable. Channel measurements in phantoms and numerical simulations with digital anatomical models provide good initial insight into the expected path loss in complex propagation media like the human body, but they often fail to capture the effects of blood circulation, respiration, and temperature gradients of a living subject. Therefore, we performed UWB channel measurements within 1-6 GHz on two living porcine subjects because of the anatomical resemblance with an average human torso. We present for the first time a path loss model derived from these invivo measurements, which includes the frequency-dependent attenuation. The use of multiple on-body receiving antennas to combat the high propagation losses in implant radio channels was also investigated. Index Terms-channel model, implant, in-body, in-vivo, path lossThis work is part of the MELODY Project-Phase II (Contract no. 225885), which is financially sponsored by the Research Council of Norway.

Spatial In-Body Channel Characterization Using an Accurate UWB Phantom

“…Implanting devices into human subjects in order to carry out propagation measurements is not possible due to ethical and physical reasons. Then, some research works have performed in vivo measurements using living animals such as pigs [9]- [11]. However, the high cost of each surgical procedure and the restrictions in animal experimentations due to ethical reasons are enough arguments to seek other solutions.…”

Anatomical Region-Specific In Vivo Wireless Communication Channel Characterization

“…The in vivo PL expresses a measure of the average signal power attenuation inside the body and calculated as P L = −mean{|S 21 |} using the channel frequency response, i.e., S 21 [4], [5]. The location dependent characteristic of the in vivo PL was investigated for two ISM bands, i.e., 915 MHz and 2.4 GHz.…”

“…The validation of numerical studies with real experimental measurements is required, however performing experiments on a living human is strictly regulated. Therefore, physical phantoms [4], [8], [16] or anesthetized animals [5], [6] are often used for experimental investigations.…”

Experimental path loss model for liver implanted wireless communication channel at ultra-wideband range

“…There have been various attempts to study UWB propagation channel at various locations inside human body e.g. chest [4], abdomen [5], [6], and brain [7]. Nevertheless, to the author's knowledge, UWB channel characteristics at liver location for liver implanted wireless monitoring system has not been reported in any open literature.…”