Implantable antenna for biomedical applications: electromagnetic, SAR, and thermal performance evaluation

Abstract

This paper presents the design and evaluation of a miniature implantable antenna for biomedical applications, optimized for narrowband telemetry at 2.402 GHz within the ISM band. The antenna achieves ultra-compact dimensions of 4 × 3.5 × 0.254 mm3 and exhibits stable impedance matching with a reflection coefficient (S11) below − 22 dB and a bandwidth of approximately 10.4%. The realized gain of − 28.3 dBi lies within the expected range for implantable devices, ensuring reliable short-range communication. Safety and biocompatibility were comprehensively assessed using CST Microwave Studio and COMSOL Multiphysics, incorporating RF exposure analysis and the Pennes bioheat equation. Results confirmed compliance with SAR limits (0.385 W/kg for 1 g tissue at 1 mW input) and showed that thermal rise remained ≤ 2 K under continuous operation. Furthermore, ex vivo validation in bovine fat confirmed the antenna’s performance in a biological environment. Overall, the study provides a comprehensive evaluation of the antenna’s electromagnetic characteristics, SAR compliance, and thermal safety, demonstrating its suitability for implantable biomedical devices such as pacemakers, neurostimulators, and biosensors.