Graphene-based implant that records brain activity at low frequencies may change our understanding of the brain

Researchers from ICN2, IMB-CNM, CSIC, IDIBAPS, and ICFO have designed a graphene-based implant able to record electrical activity in the brain at extremely low frequencies and over large areas.

The team explains that electrode arrays currently used to record the brain’s electrical activity are only able to detect activity over a certain frequency threshold. The new graphene-based technology presented in this work overcomes this technical limitation, allowing access to information found below 0.1 Hz, while at the same time paving the way for future brain-computer interfaces.

Developed at the Barcelona Microelectronics Institute (IMB-CNM, CSIC) and the Catalan Institute of Nanoscience and Nanotechnology (ICN2, a center of BIST and CSIC), and the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), and adapted for brain recordings in collaboration with the August Pi i Sunyer Biomedical Research Institute (IDIBAPS), the 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 in this new architecture means the resulting implant can support many more recording sites than a standard electrode array, and is slim and flexible enough to be used over large areas of the cortex without being rejected or interfering with normal brain function. The result is an unprecedented mapping of the kind of low frequency brain activity known to carry crucial information about different events in the brain such as the onset and progression of epileptic seizures and strokes.

Prof. Matthew Walker, of University College London and world specialist in clinical epilepsy, has called this technology 'a ground-breaking technology that has the potential to change the way we record and view electrical activity from the brain'. Future applications may provide unprecedented insights into where and how seizures begin and end, enabling new approaches to the diagnosis and treatment of epilepsy.

Beyond epilepsy, though, this precise mapping and interaction with the brain has other exciting applications. Taking advantage of the capability of the transistor configuration to create arrays with a very large number of recording sites, by employing a so-called multiplexing strategy, the technology described here is also being adapted by some of the same researchers to restore speech and communication as part of the European project, BrainCom. Led by the ICN2, this project will deliver a new generation of brain-computer interfaces able to explore and repair high-level cognitive functions, with a particular focus on the kind of speech impairment caused by brain or spinal cord injuries (aphasia).