A freestanding submicron electrocorticography electrode array

Electrocorticography electrode arrays (EEAs) are key brain-computer interfaces. To be freestanding, which lays the foundation of fabrication and implantation, EEAs need to maintain sufficient rigidity. However, to form seamless and damage-free contact on the cerebral cortex, EEAs should be super-flexible, raising a seemingly unsolvable dilemma. Here, inspired by dragonfly wings, we present a freestanding submicron EEA (fs-EEA) that combines rigidity and flexibility, which are typically mutually exclusive characteristics. A wing vein-like frame is introduced to enable the freestanding capability, while the wing membrane-like functional region of fs-EEA is reduced to 850-nm-thickness that boosts its softness. This fs-EEA ensures excellent cortical conformality and biocompatibility on male epileptic rat models, improves electrocorticographic amplitude and signal-to-noise ratio. Our vein-membrane hybrid structure strategy thus resolves the inherent contradiction of EEAs, and has the potential to support advances in brain science and related fields.