Smart-Glass-Enabled Wireless Power Transfer to Intraocular Retinal Prosthetic Devices Incorporating Oil-Infused Biocompatible Coating

Retinal prosthetic devices (RPDs) require miniaturized, biocompatible, and energy-efficient wireless links to enable reliable power delivery and data communication under harsh intraocular environments. This paper presents a smart-glass-enabled intraocular wireless power transfer (WPT) and communication platform based on an interdigitated spiral antenna integrated with an on-substrate rectifier, coated with an oil-infused biocompatible elastomer. The proposed implant is fabricated on a Rogers RT Duroid 6010 substrate with a compact size of 6.3 mm × 6 mm × 0.25 mm and achieves ultra-wideband (UWB) impedance matching from 2.2 to 8 GHz. Unlike conventional RPDs that rely on inductive coils or narrowband architectures, the proposed design enables simultaneous radiative near-field WPT and wideband communication within a single compact intraocular structure. A detailed electromagnetic analysis is conducted using a realistic eye model, which demonstrated robust impedance matching and stable transmission performance under eye rotation and transmitter (Tx)-receiver (Rx) antenna separation variations. The proposed WPT system achieved -22 dB power transfer efficiency with a Tx-to-Rx separation of 17 mm. The UWB Rx achieved a maximum measured peak gain greater than -14 dBi with a measured radiation efficiency of more than -24 dB across the 2–7 GHz frequency range. Furthermore, sensitivity analysis confirms that the antenna maintains reliable operation under ±20% variations in tissue permittivity and conductivity to account for inter-subject physiological variability. In addition, a WPT Tx is integrated into glasses to ensure wearability and to validate real-time rectification and LED illumination under saline-loaded conditions experimentally. To ensure compliance with safety regulations, a comprehensive safety analysis is conducted, including specific absorption rate and tissue heating. To assess long-term functional stability, in vitro aging studies of the oil-infused elastomer in phosphate-buffered saline at physiological and accelerated temperatures are conducted, followed by gravimetric, radio-frequency (RF), and spectroscopic analyses to verify sustained surface integrity, functional stability, and the absence of oil leaching over time.