Longitudinal Brain Activity Tracking with a Wireless Implantable Sensor Enabled by Wearable Metasurfaces

Electroencephalography (EEG) is an essential tool for measuring brain activity in preclinical animal models and diagnosing neurological diseases and disorders in clinical settings. Traditional wired EEG systems are bulky, restrict mobility, and cause discomfort, limiting studies involving subjects in motion. The need for versatile, portable testbeds has driven the development of compact, wireless EEG biosensors. However, miniaturizing EEG biosensors poses challenges in power supply and data communication. Current wireless EEG biosensors depend on bulky batteries that require frequent replacement, and their wireless modules consume significant power, limiting data rates to conserve energy, which restricts continuous data acquisition over extended periods.

Metasurfaces, which are engineered two-dimensional sub-wavelength structures, offer a promising approach to addressing these challenges by enabling efficient wireless power transfer and high-speed communication without adding significant weight. Their ability to tailor electromagnetic responses opens new possibilities for integrating power functionalities into compact biosensors. In this talk, I will discuss a compact, fully implanted biosensor enabled by metasurface-based wireless power and communication. The integrated signal conditioning block supports two-channel EEG signal measurement and communicates with a host computer via Bluetooth low energy protocol in vivo. The implant's flexible material design is suitable for long-term EEG signal acquisition, providing up to a 13.7-fold enhancement in wireless power transfer efficiency in tissue and enabling sustained data acquisition over extended periods.