Robust implantable antenna for in-body communications

Abstract

A compact implantable printed meandered folded dipole antenna with a volume of 101.8 mm 3 and robust performance is presented for operation in the 2.4 GHz medical ISM bands. The implant antenna is shown to maintain its return loss performance in the 2360-2400 MHz, 2400-2483.5 MHz and 2483.5-2500 MHz frequency bands, simulated in eleven different body tissue types with a broad range of electrical properties. Bandwidth and resonant frequency changes are reported for the same antenna implanted in high water content tissues such as muscle and skin as well as low water content tissues such as subcutaneous fat and bone. The antenna was also shown to maintain its return loss performance as it was moved towards a tissue boundary within a simulated phantom testbed.

Effect of tissue boundaries on the intra-body communication channel at 2.38 GHz

“…Different tissues exhibit different dielectric properties and this may mean that antennas need to be modified or re-tuned each time the device's position changes with respect to the surrounding tissues. Of course, this challenge is somewhat mitigated by using multiresonance antennas [4] and to some degree by the required biocompatible insulating layer for the antenna. Insulation improves radiation efficiency as near field losses are reduced and it prevents the short circuit effect associated with highly conductive tissue materials such as skin and muscle [2], [5].…”

Unidirectional Uwb Magneto-Electric Antenna for Medical Telemetry

“…It covers an appreciable 100% out of the 110% impedance bandwidth of an entire UWB (3.1-10.6 GHz) for WBAN. As expected from implantable antenna under ideal laboratory experimental situation, this result in bandwidth could differ slightly because tissue conductivity is known to decrease with permittivity between high and low water content tissues [16].…”

Miniaturized Capsule System Toward Real‐Time Electrochemical Detection of H2S in the Gastrointestinal Tract

“…Bluetooth, which operates at 2.45 GHz, is a low‐power, point‐to‐point communication protocol that permits a compact antenna footprint and is widely compatible with consumer electronic products. Known challenges of wireless communication for ingestible electronics include inefficient signal propagation within the GI tract, due to the high radio frequency (RF) signal attenuation in abdominal tissues ( ε r = 52.8), [ 78 ] high current consumption compared to sensing circuitry, and limited high‐density battery chemistries that support high current consumption (≈10 mA) in a capsule form factor. To simulate the expected RF attenuation in vivo, the capsule was surrounded by 100 mm of ground meat (88% lean, 12% fat) on all sides (Figure S9, Supporting Information), and wireless signal attenuation testing was performed.…”