Ultraflexible, Biodegradable ECoG Arrays via Rapid Fabrication Enables High-Resolution Cortical Mapping and Seizure Network Classification In Vivo

Neural interfaces are essential tools for diagnosing and managing neurological disorders, yet conventional electrocorticography (ECoG) devices are limited by mechanical mismatch with brain tissue, chronic inflammation, and poor scalability. Here, we introduce a fully inkjet-printed, flexible, and biodegradable ECoG array fabricated on ultrathin polycaprolactone films with gold nanoparticle electrodes. The arrays achieve among the highest electrode densities reported for additive manufacturing (7.44 electrodes/mm{superscript 2}) while maintaining low impedance (10.6 k{Omega} at 1 kHz) and high-fidelity recordings (SNR 28 dB). A rapid, maskless prototyping process relying on photonic sintering enables scalable, cost-effective fabrication. In vivo, the devices conformally mapped cortical seizure propagation and resolved distinct ictal dynamics in a rat model. Histology at 30 days confirmed preserved neuronal density and astrocytic response comparable to controls, indicating minimal chronic inflammation. A convolutional neural network trained on recorded signals classified seizure stages with >95% accuracy, underscoring the translational potential for real-time monitoring and closed-loop neuromodulation. This platform unites rapid prototyping, biodegradability, and high performance, providing a scalable route toward next-generation, patient-specific, and disposable neural interfaces for epilepsy and other neuroengineering applications.