Miniaturized Antenna for High Data Rate Implantable Brain-Machine Interfaces

Technological advancements in medical care have necessitated the development of efficient and miniaturized implantable medical devices. This paper presents an ultra-wide-band implantable antenna for use in scalp-based biomedical applications covering the industrial, scientific, and medical (ISM) (2.4-2.48 GHz) band. The proposed antenna is mounted on a 0.1-mm thick liquid crystalline polymer (LCP) Roger ULTRALAM (tan delta =0.002 and epsilon(r) =2.9), serving as a dielectric material for both the superstrate and substrate layers. LCP materials are widely used in manufacturing electronic devices owing to their desirable properties, including flexibility, conformable structure, and biocompatibility. To preserve the capability of an electrically small radiator and achieve optimum performance, the proposed antenna is designed to have a volume of 9.8 mm(3) (7 mm x 7 mm x 0.2 mm). The addition of a shorting pin and open-ended slots in the radiating patch, and close-ended slots in the ground plane facilitates antenna miniaturization, impedance matching, and bandwidth expansion. Notably, the antenna exhibits a peak gain of -20.71 dBi and impedance-matched bandwidth of 1038.7 MHz in the ISM band. Moreover, the antenna is safe to use according to the IEEE C905.1-2005 safety guidelines based on low specific absorption rates. To evaluate the performance of the implantable antenna, finite-element simulation was performed in homogeneous and heterogeneous environments. For validation, measurements were performed in a minced pork-filled container. The simulation results are consistent with the measurements. In addition, a link budget analysis is performed to confirm the robustness and reliability of the wireless telemetric link and determine the range of the implantable antenna.