Flexible Dual-Polarized UWB Antenna Sensors for Breast Tumor Detection

Early breast cancer detection is crucial for improving survival rates and saving lives. The study proposes a breast tumor sensing system utilizing compact and adaptable dual-polarized Ultra-Wideband (UWB) antenna arrays. These arrays, consisting of two circular monopoles on flexible Kapton polyimide substrates, and offer both compactness and flexibility.

Ultra-wideband (UWB) near-field imaging emerges as a simple, robust, and cost-effective method, leveraging tumor dielectric properties. In active radar imaging, antennas illuminate breast tissues, utilizing signal reflections and scatterings for reconstruction. The system's accuracy relies heavily on UWB antenna design, particularly on flexible substrates preferred for their compactness and resilience to environmental factors.

These UWB antenna arrays, particularly those based on Kapton polyimide, provide wearability and reliability, demonstrated by monitoring healthy volunteers over 28 days. Advancements include planar UWB arrays that detect multiple tumors and successfully detect two tumors even 63 mm apart using wideband linearly moving antennas.

Compact, flexible dual-polarized UWB antennas on Kapton polyimide achieve high-resolution tumor imaging within a 3.9-19 GHz bandwidth. The antenna design integrates a circular monopole fed by coplanar waveguides. It is validated through simulations. The stable performance across different layers of breast tissue highlights its suitability for tumor sensing.

To enhance tumor detection, eight UWB units surround a breast phantom, reconstructing three-dimensional images through the delay-and-sum (DAS) algorithm. The system accurately locates and measures the sizes of tumors while minimizing clutter interference. It can even detect two tumors with a narrow 15 mm edge-to-edge distance.

In the experiment, researchers tested three setups with different numbers and locations of tumors, each represented as 10 mm cubes. ,  The antenna's performance on skin, fat, and glandular layers of the tissue was examined using signals between 3.7 GHz to 11 GHz for reconstruction. Lower frequencies were effective for detecting deeper tumors, while higher frequencies focused on superficial ones.

The DAS algorithm, which utilized modulated Gaussian pulse excitation, processed signals received from all antennas. Through simulations, tumor-free responses were obtained by rotating the phantom, enabling the removal of unwanted signals. Furthermore, the algorithm distinguished tumor information from undesired signals through calibration and differential analysis, reconstructing a 3D image of the breast and tumor.

The experiment demonstrated the superiority of dual-polarized antennas in multi-tumor detection, offering precise tumor localization while minimizing noise clutter. It highlighted the system's advantages, such as its compact, flexible design and robust performance, surpassing other UWB imaging systems in detecting multiple tumors and image quality.

The design fabrication of the system involves utilizing oil-in-gelatin mixtures for breast phantoms to match simulation electric properties. Measurement setups employ a rotating platform and open-end coaxial probe method for precise permittivity measurement, confirming accurate tumor detection.

In conclusion, the flexible dual-polarized UWB antenna array presents a promising solution for breast tumor detection. Experimental validation on rotating platforms confirms the system's effectiveness for wearable applications, promising convenient and cost-effective breast cancer screening methods. The system accurately locates and sizes tumors with minimal interference, offering the potential for wearable health monitoring as a convenient alternative to hospital diagnosis.