Study of a wideband high data rate implantable antenna for cortical visual prosthesis

A compact wideband high data rate implantable antenna is designed for cortical visual prosthesis devices. In order to achieve high data rate, a metamaterial array with negative permeability is formed by loading complementary open resonant rings to reduce the resonant frequency of the antenna and produce circular polarization characteristics. By introducing a meandering structure around the radiation unit, the current path on the antenna surface can be increased, further optimizing the impedance matching. Adding four U-shaped open slots on the ground plane can increase two adjacent resonant points, reducing the antenna size while increasing the impedance bandwidth. The antenna size is reduced to 8 × 8 × 0.635 mm³. A complete antenna model is established, and the biocompatibility, radiation characteristics and safety of the antenna are evaluated. The performance of the antenna is tested in a saline solution simulating the characteristics of cerebrospinal fluid. The measured impedance bandwidth is 26.5%, the axial ratio bandwidth is 22.3%, the gain is -20.9 dBi, and the effective communication distance is 4.1 m. The designed antenna has wide working frequency band, small size, good electromagnetic compatibility and high data rate communication ability, and is the optimal design scheme for cortical visual prosthesis.