Study on Fat as the Propagation Medium in Optical-Based In-Body Communications

This paper investigates fat tissue as a medium for communication in implantable/ingestible medical device (IMD) systems based on optical wireless communication (OWC). The findings emphasize the importance of tissue characteristics (temperature in particular) for optimizing OWC performance. This study considered Near-infrared (NIR) light with 810 nm wavelength and fresh porcine samples to mimic the human tissue. The study employs a realistic measurement approach in an ex vivo setting using various porcine samples: pure fat and flesh tissues and samples with different thicknesses. This study also investigates the influence of porcine temperature on the optical communication channels, which are measured by comparing the received optical power at 23 °C and 37 °C. In general, tissue samples at warmer temperatures (37 °C) receive higher optical power than colder samples. The results also demonstrate the superior optical power transmission capabilities of pure fat compared to pure flesh in porcine tissue samples in warm conditions. We also found that porcine with multiple layers of fat (fatty sample) yields higher received optical power than porcine with multiple layers of flesh (muscular). The results of this study provide valuable insights and relevant considerations for OWC-based in-body communication conducted using porcine samples.