Conformal bumped electrode web for chronic ECoG recordings in swine

The acquisition of high-quality electrocorticogram (ECoG) signal is of great significance for the diagnosis and treatment of neurological diseases such as high amputation, visual injury, epilepsy and Parkinson’s disease. Currently, flexible ECoG electrodes have received attention due to their low mechanical mismatch and minimally invasive characteristics. However, the traditional ECoG electrodes are non-stretchable planar structures that cannot be conformal with the cerebral cortex, which is in constant motion and has sulci and gyri structure. In this work, a flexible stretchable ECoG electrode with bumped electrodes was developed to alleviate these problems. Firstly, the mechanical simulation results show that this stretchable electrode structure can effectively reduce the stress mismatch between electrode and tissue interface. Secondly, the results of cyclic voltammetry scanning and mechanical tensile experiments show that the stretchable ECoG electrode structure can be conformally attached to the surface of the cerebral cortex and maintain good electrochemical stability during continuous stretching. Third, the bumped electrode has a larger adhesive force than the planar electrode and can significantly reduce the background noise by conformal attachment and electrochemical modification of PEDOT:PSS. Most importantly, in vivo animal experiments showed that the stretchable ECoG electrode can continuously record high-quality ECoG signals on the surface of the cerebral cortex of swine over an area of 22 × 22 mm2 for more than 5 weeks.