The Effect of Insulating Layers on the Performance of Implanted Antennas

Abstract

Abstract-This work presents the analysis of the influence of insulation on implanted antennas for biotelemetry applications in the Medical Device Radiocommunications Service band. Our goal is finding the insulation properties that facilitate power transmission, thus enhancing the communication between the implanted antenna and an external receiver. For this purpose, it has been found that a simplified model of human tissues based on spherical geometries excited by ideal sources (electric dipole, magnetic dipole and Huygens source) provides reasonable accuracy while remaining very tractable due to its analytical formulation. Our results show that a proper choice of the biocompatible internal insulation material can improve the radiation efficiency of the implanted antenna (up to six times for the investigated cases). External insulation facilitates the electromagnetic transition from the biological tissue to the outer free space, reducing the power absorbed by the human body. Summarizing, this work gives insights on the enhancement of power transmission, obtained with the use of both internal, biocompatible and external, flexible insulations. Therefore, it provides useful information for the design of implanted antennas.

Optimal Radiation of Body-Implanted Capsules

“…For TE 10 , max (η) = 1.8 × 10 −3 T + 0.02 R2 = 1 . These results are consistent with the findings of Merli et al [26]. Note that if ε r,S = ε r,1 , thicker shell would also affect the optimal frequency by increasing the effect of ε r,S described above.…”

Electromagnetic Radiation Efficiency of Body-Implanted Devices

“…Σt (d < 0) consists of muscle, fat, and skinequivalent layers. (c) Circular heterogeneous phantom (not to scale) similar to the one used in [18,19]. Σt (R < 90) includes dispersive layers with muscle-, fat-, and skin-equivalent EM properties.…”

“…Next, we model a human body as an infinitelylong three-tissue stratified cylinder (Figure 2c) with the same radii as for the spherical phantom used by Merli et al [18], Chrissoulidis and Laheurte [19]. Consi- dering the magnetic dipole source (TM z mode) at d = 1-4 cm, the efficiency η idl is about five times higher than the one for the planar media due to 1) weakened attenuation in the finite-sized lossy domain Σ t and 2) reduced effect of the total internal reflection [Figures 1(d) and 1(e)] because of the tissue-air boundary encircling the source (Figure 8).…”

A Study on Application of Dielectric Resonator Antenna in Implantable Medical Devices

“…The shift from the medical implant communication service (MICS) band (402-405 MHz) to industrial, scientific and medical (ISM) band (902-928 MHz and 2400-2483.5 MHz) is understandable due to the higher gain and possible miniaturization of implantable antennas. Different design considerations regarding implantable antennas have been discussed in [2]- [9] . Ingestible antennas [10]- [14] and ISM band implantable antennas [15]- [25] have also been discussed for diagnostics and monitoring purposes.…”