A newly-developed graphene-based implant can record electrical activity in the brain at extremely low frequencies and over large areas, unlocking the wealth of information found below 0.1Hz. Researchers have been using electrode arrays to record the brain’s electrical signals for decades, mapping activity in different brain regions to understand its inner workings. Until now, however, these arrays have only been able to detect activity over a certain frequency threshold. A new technology developed by the Graphene Flagship overcomes this technical limitation, at the same time paving the way for future brain-computer interfaces. “This work is a prime example of how a flexible, graphene-based transistor array technology can offer capabilities beyond what is achievable today and open up tremendous possibilities for reading at unexplored frequencies of neurological activity,” said Kostas Kostarelos, leader of the Health, Medicine and Sensors Division of the Graphene Flagship that developed the technology, in cooperation with the Barcelona Microelectronics Institute (IMB-CNM, CSIC), the Catalan Institute of Nanoscience and Nanotechnology (ICN2) and ICFO. The new technology moves away from electrodes and uses an innovative transistor-based architecture that amplifies the brain’s signals in situ before transmitting them to a receiver. The use of graphene to build this architecture means the resulting implant can support more recording sites than a standard electrode array. It is slim and flexible enough to be used over large areas of the cortex without being rejected by the body or interfering with the brain’s normal functions. The result is an unprecedented mapping of the low-frequency brain activity known to carry crucial information about different events, such as the onset and progression of epileptic seizures and strokes. The technology could change the way electrical activity from the brain are viewed and recorded, helping identify where seizures begin and end, and enabling new approaches to the diagnosis and treatment of epilepsy, for a start. The Graphene Flagship is one of the largest research projects funded by the European Commission. It boasts a budget of €1bn over 10 years, bringing together academic and industrial researchers to take graphene from academic laboratories into commercial markets, thus generating economic growth, jobs and opportunities for Europe.