Heterointegration Technologies for Advanced 3D Neural Interfaces

Understanding the neurological processes by which humans perceive and act requires development of electro-neural interfaces with resolution that can probe at the single cell or sub-cellular level in a network of a large population of neurons. Si nanowires have been demonstrated as excellent nanoscale neural probes that can penetrate into the neural cell body and measure intracellular action and local field potentials. However, for individual addressability of single Si nanowires in a large scale assembly that is capable of probing neural activity at high spatial and temporal resolution, new integration technologies are required. To accomplish this task, we developed a novel all-solid state wafer bonding technique that allows integration of high-quality Si 3D structures to patterned (electrically isolated) electrode leads on insulating substrates. One key advantage of this technology is that the bonding layers (leads) are conductive, requiring no further processing for electrical addressability. Electrophysiology experiments validated the operation of such probes in high densities. In addition, co-integration and independent multiplexing of microfluidic channels within each nano-electrode is possible. This approach is fab-compatible, easy to manufacture, and allows integration of a variety of sensor and stimulator/inhibitor material elements on arbitrary substrates.