Enabling high-throughput multimodal sensing in three-dimensional cell cultures using novel high-performance CMOS circuits

It has been shown that electrical stimulation of the visual cortex through implanted microelectrode arrays (MEAs) can create the perception of sight in visually impaired subjects. However, the current state-of-the-art electrode implants only allow the stimulation of hundreds of brain locations, which is insufficient to create a usable image of the world that can enable basic navigation or advanced sight. Advanced integrated-circuit fabrication technologies coupled with special post-processing techniques have the potential to create large, flexible chips containing tens of thousands of electrodes that can be placed directly on the brain. Imec is currently developing fabrication techniques to produce web-like sensor arrays that can achieve the required flexibility to follow the folds of the brain, and sufficient tissue compliance for in-vitro cell-interfacing applications. The main objective of this Ph.D. project is to design and implement ultra-low-power and ultra-small readout and stimulation circuits that can be monolithically integrated into the pixel islands that form the web-based MEAs. An efficient and fault-tolerant power distribution and communication scheme must be implemented to enable the data transfer between pixels and across the whole array, even when pixel connections break. One of the main challenges in this circuit design is to achieve a high density and a large number of stimulation and recording pixels that meet the specifications of the application: e.g. low noise, high dynamic range, and flexible stimulation parameters. This Ph.D. work will also require circuit layout and chip integration, circuit validation, system development, and demonstration in a biological setting.