Abstracts

Rationale: In all current brain-machine interface devices for both clinical and research applications, each electrode is independently connected to separate control systems. Examples of such devices include penetrating microelectrode arrays and cortical surface electrode arrays, and systems such as deep brain stimulators and epilepsy treatment devices. These individually wired electrodes limit both the number and configuration of the electrodes that can be used to sample and stimulate tissues. Active circuits to reduce this wiring burden are limited by the mismatch between the rigid, planar nature of conventional, silicon electronics and the irregularly shaped tissue surfaces. Methods: Flexible electronics that are capable of intimate, non-invasive integration with the soft, curvilinear surfaces of the brain offer important opportunities for diagnosing and treating disease and for improving brain-machine interfaces. Results: Here, we report new dense arrays of multiplexed electrodes using flexible electronics that can enable an unprecedented level of spatial and temporal electrocorticographic (ECoG) resolution over large areas of cortex. The extreme flexibility of the devices can further enable simultaneous sampling of gyral and intrasulcal ECoG to sample regions of the brain that were previously inaccessible or difficult to reach, but are known to carry enormously important information. We demonstrate this technology in a sensor system composed of 720 silicon nanomembrane transistors configured to record electrical activity directly from the feline brain in vivo. The device samples with simultaneous submillimeter and submillisecond resolution through 360 amplified and multiplexed channels, requiring only 39 external wire connections. The design can be scaled up to much larger sizes, without dramatically increasing the number of external connections. We use this system to map visual and stimulation evoked potentials at high resolution, on the surface of primary visual cortex. Conclusions: This demonstration is one example of many possible uses of this technology in a new generation of minimally invasive clinical and research devices for medical and brain-computer interface applications.