Hollow ring-like flexible electrode architecture enabling subcellular multi-directional neural interfacing

Implantable neural microelectrodes for recording and stimulating neural activity are critical for research in neuroscience and clinical neuroprosthetic applications. A current need exists for developing new technological solutions for obtaining highly selective and stealthy electrodes that provide reliable neural integration and maintain neuronal viability. This paper reports a novel Hollow Ring-like type electrode to sense and/or stimulate neural activity from three-dimensional neural networks. Due to its unique design, the ring electrode architecture enables easy and reliable access of the electrode to three-dimensional neural networks with reduced pressure on the biological tissue, while providing improved electrical interface with cells. The Hollow ring electrodes, particularly when coated with the conducting polymer PEDOT:PSS, show improved electrical properties with extremely low impedance and high charge injection capabilities, when compared to traditional planar disk-type electrodes. The ring design also serves as an optimal architecture for cell gowth to create an optimal subcellular electrical- neural interface. In addition, we demonstrated that the quality of recorded neural signals by the ring electrode was higher than recordings from a traditional disk-type electrode in terms of signal-to-noise ratio (SNR) and burst detection from 3D neuronal networks in vitro. Overall, our results suggest the great potential of the hollow ring design for developing next-generation microelectrodes for applications in neural interfaces used in physiological studies and neuromodulation applications.