Design and Evaluation of Antenna System for Non-Invasive Detection of Intracranial Hemorrhaging

Abstract

Intracerebral hemorrhage (ICH) is a life-threatening form of stroke, responsible for approximately 3.3 million deaths annually worldwide and contributing to a global economic burden exceeding $890 billion per year. Clinical evidence shows that early detection and rapid intervention significantly reduce mortality, underscoring the need for fast and reliable diagnostic techniques. In this study, we propose a low-cost, portable microwave-based system for early detection of intracerebral hemorrhage. The system integrates a wearable circumferential antenna array for signal transmission and reception with an image reconstruction algorithm for recovering internal brain structures, enabling rapid and non-invasive detection of hemorrhagic regions. A major challenge in such systems is that microwave signals radiated by the antennas propagate in multiple directions, causing neighboring antennas to receive not only signals transmitted through brain tissues but also unwanted components traveling outside the region of interest. These undesired signals do not contain useful intracranial information and can degrade imaging accuracy. To mitigate this issue, dielectric gel is applied to the lateral and posterior sides of the antennas to suppress these unwanted signal components. To achieve this, we focus on the dielectric properties of the gel, specifically its relative permittivity and conductivity. Through controlled comparative evaluations, the effects of permittivity and conductivity are systematically investigated, and optimal values are identified at approximately 40 and above 5 S/m, respectively. Based on these target properties, a material is synthesized using silicone rubber as the base matrix and carbon black (CB) as a conductive filler. The fabricated material exhibits a relative permittivity of approximately 15 and a conductivity around 15 S/m, approaching the target values while remaining practically realizable. The proposed material is incorporated into the antenna configuration within a simplified head model in electromagnetic simulations. The antennas placed along the lateral and posterior sides are loaded with the synthesized material, and the resulting S-parameters are collected for image reconstruction using the Delay-Multiply-and- Sum (DMAS) algorithm. The reconstructed images demonstrate improved localization of hemorrhage regions compared to the case without gel, showing clearer and more focused imaging results.