Skin-Like Electronics for a Persistent Brain- Computer Interface

There exists a high demand for a continuous, persistent recording of non-invasive electroencephalograms in both clinical and research fields. Head-cap electrodes with metal conductors and conductive gels are widely used and considered as the gold standard for such measurement. This physical interface, however, is poorly suited to uninterrupted, long-term use due to the uncomfortable rigid electrodes, skin irritation due to the gel, and electrical degradation as the gel dries. These issues can be addressed by using a newly developed, dry form of electronics. Here, we briefly review a class of soft electronic technology in the aspects of mechanics, materials, and its capabilities for a long-term recording of electroencephalograms and a brain-computer interface (BCI). We summarize the progress in the development of a skin-like electronic system with a focus on key mechanical factors to achieve conformal skin contact. The design of hard electronics, integrated with soft membranes, uses deterministic fractal motifs to offer bending and stretching mechanics. We also introduce a most recent example of such electronics, an ‘auricle-integrated system’, which includes a strategy of conformal integration on the complex surface topology, a quantitative study of biocompatibility, and an application as a persistent BCI. Journal of Nature and Science, 1(7):e132, 2015.