Bioresorbable, Ultra-Flexible, Inkjet-Printed, Gold Nanoparticles-Based Neural Interface

Abstract

Electrocorticographic brain-computer interfaces (ECoG-BCIs) provide a powerful tool for both therapeutic and research applications by directly recording electrical activity from the brain's surface. With the limitations of pharmacological treatments for many neurological disorders, such as epilepsy, this technology offers significant potential for improving patient outcomes by enabling precise mapping of brain activity. However, conventional ECoG systems, built on rigid substrates, struggle to conform to the brain's contours, limiting their effectiveness and posing long-term biocompatibility challenges due to their non-bioresorbable nature. In this work, an ultra-flexible, bioresorbable inkjet-printed electrode array was developed to address these limitations. The array, consisting of 36 gold electrodes each 75 μm in size, was fabricated within an approximately 2x2 mm area on a polycaprolactone (PCL) substrate using inkjet printing and photonic sintering. These approaches allow for processing at room temperature, which is essential for maintaining the integrity of the heat-sensitive polymer. Electrochemical and mechanical characterizations confirmed the device's excellent performance with an impedance near 1 kΩ at 1 kHz, and in vivo testing in rats confirmed its ability to reliably record brain activity, detect various forms of seizures with a signal-to-noise ratio (SNR) of 28, and generate heat maps to track the spatial and temporal evolution of brain activity. The device’s flexibility, stability, biodegradability, and biocompatibility were further evaluated, positioning it as a safer, long-term solution for brain activity monitoring. This novel design enhances the adaptability of ECoG systems to the brain's complex structures, improves electrode density, reduces the invasiveness, and offers a time- and cost-effective solution, positioning it as a promising advancement in ECoG technology.