Researchers from various centers in Barcelona have developed a graphene-based implant capable of detecting brain electrical activity at extremely low frequencies and on large surfaces. This breakthrough technology could allow a deeper knowledge of the brain and facilitate the arrival of a new generation of brain-computer interfaces.
The knowledge we have about the human brain grows exponentially, but there are still big and small questions waiting to be answered. The research community has used electrode guides for decades to detect electrical activity in the brain, mapping the activity of its different regions.
In spite of this, until now these electrodes have only been able to detect the activity above a certain frequency threshold. A new technology developed in Barcelona overcomes this technical limitation, making accessible the large volume of information below 0.1 Hz, and at the same time facilitating the design of future brain-computer interfaces.
The Institute of Microelectronics of Barcelona (IMB-CNM, CSIC), the Institut Català de Nanociència i Nanotecnologia (ICN2) and the Center of Biomedical Research in Network for Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) have been the architects of this technology, which was adapted for its use in the brain at the Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS). This technique leaves classical electrodes behind and uses an innovative transistor-based architecture that amplifies brain signals in situ before transmitting them to the receiver.
In addition, the use of graphene in the manufacture of this new architecture means that the resulting implant can incorporate many more detection points than a standard electrode guide, while being sufficiently thin and flexible to be able to be applied over large areas of the cortex, without causing rejection or interfering with the normal functioning of the brain.
The result is an unprecedented mapping of low frequency brain activity where crucial information is found on different events that take place in the brain, such as the onset and progression of an epileptic seizure.
With this technology neurologists will finally have access to the subtlest signals in the brain. Matthew Walker, of University College London and a global specialist in clinical epilepsy, has stated that this breakthrough technology has the potential to change the way electrical activity in the brain is measured and visualized. Its future applications will offer an unprecedented understanding of where and how attacks begin and end, enabling new approaches for the diagnosis and treatment of epilepsy.
Beyond epilepsy, the precise mapping and interaction of the brain has other interesting applications. Thanks to the ability to create a matrix with a large number of detection points via multiplexing strategy (a way of sending multiple signals or streams of information over a communications link at the same time in the form of a single, complex signal), some of the authors of this work are also adapting technology to restore the ability to speak and communicate, as part of the European project BrainCom.
Coordinated by the ICN2, this project will provide a new generation of brain-computer interfaces capable of exploring and repairing complex cognitive functions, with a special interest in the loss of speech caused by brain or spinal cord injuries (aphasia).
The details of the technological advances (patent pending) that have made these implants possible can be found in Nature Materials. The graphene micro-transistors were adapted for the reading of brain signals and tested in vivo in the IDIBAPS, under the supervision of ICREA. The image technique was developed in collaboration with ICFO, a contribution also led by ICREA.