Electrically Small Circularly Polarized UWB Intraocular Antenna System for Retinal Prosthesis

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Materials Science

Background:

• Retinal prosthesis systems require miniaturized, high-performance communication modules for artificial vision.
• Existing intraocular antennas face challenges in achieving wide bandwidth and circular polarization within strict size constraints.

Purpose of the Study:

• To design and validate an electrically small, circularly polarized antenna system for intraocular retinal prosthesis applications.
• To achieve high programmability for retina stimulation and recording using ISM and ultra-wideband (UWB) frequencies.

Main Methods:

• Designed a 3x3 mm² wire patch antenna system with a ground plane of λ0/41 x λ0/41 x λ0/191.
• Utilized polyimide encapsulation with stubs to combine TM010 and higher-order modes for wideband impedance matching (2-11 GHz).
• Incorporated annular rings and shorting pins for circular polarization (CP) at 2.45, 5.8, and 8 GHz, simulated in eye and head models using Ansys HFSS.

Main Results:

• Achieved a -10 dB impedance bandwidth of 2-11 GHz and 3-dB axial-ratio bandwidths of 0.3, 0.16, and 1.2 GHz at 2.45, 5.8, and 8 GHz, respectively.
• Obtained left-hand circularly polarized (LHCP) gain up to -4.7 dBic in the broadside direction.
• Validated simulated results with measurements in a custom eye model and head phantom, showing reasonable agreement.

Conclusions:

• The designed intraocular antenna system meets the stringent size and performance requirements for retinal prosthesis.
• The antenna's wideband and CP characteristics support high data rates essential for advanced artificial vision systems.
• Fabricated antenna performance aligns with simulations, confirming its viability for implantable applications.