A polyimide-based 3-D ultrathin bioelectrode with elastic sites for neural recording

Flexible sheet electrode can record electrocorticography signals without penetrating the blood-brain barrier. However, the attachment between the cortex and the electrode influences the quality of the signal directly. Here, we present a 3-D ultrathin bioelectrode with elastic electrode sites to achieve conformal coverage on brain tissue and increase the flexibility of the electrode. Inspired by kirigami, the micro-warping elastic structures on the electrode can increase the conformality significantly when compared with the conventional planar electrodes. It has been proved that the warping structure has an excellent springback curve and maintains at least one week under the maximum stress of 7.5 kPa. Furthermore, the electrode sites were modified with platinum black to improve the electrochemical performance, and electrochemical characterization was performed. The electrode was compared with a plane one in vitro, which demonstrated the prominent attachment performance from the surface with sulci. Finally, the local field potential was recorded in vivo.