Pioneering research: non-invasive brain stimulation with superior accuracy - ERC Consolidator Grant for Charité neuroscientist Surjo Soekadar

Prof. Surjo Soekadar, Einstein Professor of Clinical Neurotechnology at Charité – Universitätsmedizin Berlin, works in the field of advanced technologies for brain stimulation and brain-computer interfaces. He and his team develop and test systems that enable communication between the brain and external devices. Applications for these technologies include ways for severely paralyzed patients to control exoskeletons using their thoughts alone. Still, these systems are reaching their limits, and areas of the brain located deeper inside the skull are difficult to reach. Now, researchers hope to change that with a new generation of these interfaces that are equipped with high-resolution sensors and use a highly effective stimulation method. The European Research Council (ERC) is providing about two million euros in funding over the next five years to support these efforts.


Brain-computer interfaces (BCIs) work based on the electrical fields generated by the brain itself, which can be measured through the scalp. BCIs use this information to translate brain activity into signals to control external devices, such as prostheses, robots, and exoskeletons. This method can allow people with severe paralysis to move or communicate. There are also “bidirectional” BCIs, which can deliver targeted electrical stimulation to prompt brain activity, thereby simulating the perception of touch when a person controls a prosthesis, for example. BCI systems are medically useful in areas such as neurological rehabilitation, where they can be used for goals like restoring the ability to communicate or move in people with the severest forms of paralysis.

Broadening the range of treatments involving BCIs

Soekadar is on a mission to improve quality of life for people with neurological and psychiatric diseases and disorders. He has been in charge of the Research Section Translation and Neurotechnology and the Clinical Neurotechnology Laboratory at the Department of Psychiatry and Neurosciences at Campus Charité Mitte for five years now. Soekadar recognized the therapeutic potential of BCI systems early on. In addition to restoring sensorimotor functions, the goal now is to use BCIs to treat psychiatric disorders. Soekadar plans to use the new funds provided by the European Research Council to overcome significant hurdles on the path to safe and effective bidirectional brain-computer interfaces that are noninvasive.

Arguably the biggest of these impediments is the human skull itself. When brain activity is measured from outside the bones through methods such as electroencephalography (EEG), BCI accuracy has been limited so far. But implanting electrodes or sensors into the skull is a laborious and high-risk process. Soekadar’s team is looking for alternatives. They are currently testing the use of quantum sensors, a type of ultra-precise sensor which can measure brain activity on the surface of the head with significantly greater accuracy than EEG and other non-invasive methods. With support from the Einstein Foundation Berlin and in cooperation with the Physikalisch-Technische Bundesanstalt (PTB), Germany’s national metrology institute, and Technische Universität Berlin (TU Berlin), a prototype version of this kind of quantum BCI has already been created. The high-tech sensors are based on gaseous atoms that work as magnetic field probes, responding to electrical signals generated by the brain. These are known as optically pumped magnetometers (OPMs).

World’s first non-invasive bidirectional brain-computer interface

Even with the rapid advances being made in neurotechnology, there is not yet a bidirectional BCI based on non-invasive methods – that is, techniques that do not require any surgical intervention. There are two reasons for this. One is the sensitivity required of the sensors, and the other is the strength of the stimulation needed to reach the brain through the bones of the skull. Other signals arising in the process can interfere, making it impossible to measure and interpret brain signals reliably, at least so far. “This is exactly the problem we aim to solve,” Soekadar explains. “Here at Charité, we plan to develop the world’s first bidirectional brain-computer interface based on quantum sensors and a method called temporal interference magnetic stimulation, or TIMS for short, a highly effective form of neurostimulation. Our aim is to make this system accessible to alleviate symptoms of psychiatric disorders such as depression.”

TIMS, the novel brain stimulation method, is to play a key role in this. TIMS is based on overlapping magnetic fields that reinforce or attenuate each other. Soekadar’s research team established the principle in their work under a previous ERC Starting Grant and then built a prototype with support from the SPARK-BIH innovation program. Now, as part of the upcoming BNCI2 ERC Consolidator Grant project, plans call for expanding on the prototype and ultimately combining it with the quantum BCI. “This combination is set to unlock a wide range of possibilities for both research and clinical applications,” Soekadar says. For example, it should make it possible to stimulate activity in even deeper areas of the brain, depending on certain brain states.

Using high-resolution quantum sensors should also allow for a level of measurement accuracy that was previously only available with invasive methods. “We hope to use the system to identify patterns of activity in the brain that are responsible for producing certain clinical symptoms. Then, as the second step, we plan to target these symptoms through a closed-loop neuromodulation,” Soekadar explains. Because the system is a non-invasive one, it will be available for broad clinical use, achieving lasting improvement in quality of life for many patients. At the same time, there are ethical challenges and cybersecurity aspects to navigate as the researchers forge ahead into previously unknown dimensions of therapeutic neuromodulation.

Prof. Surjo R. Soekadar
After studying medicine at Johannes Gutenberg University Mainz, Ruprecht Karls University Heidelberg, and University of Maryland / Johns Hopkins University in Baltimore (USA), Surjo Soekadar earned his doctorate at the Central Institute of Mental Health (CIMH) in Mannheim in 2005. He went on to complete his residency in psychiatry and psychotherapy at the University Hospital for Psychiatry and Psychotherapy in Tübingen and spent three years as a visiting fellow at the National Institute of Neurological Disorders and Stroke (NINDS) in Bethesda, Maryland. After returning to Tübingen, Soekadar became the head of the Applied Neurotechnology Research Group and completed the habilitation process in 2017. In 2018, he was appointed to serve as Germany’s first professor of clinical neurotechnology at Charité – Universitätsmedizin Berlin, with support from the Einstein Foundation Berlin.

ERC Consolidator Grant
ERC Consolidator Grants are designed to support excellent Principal Investigators who are pursuing groundbreaking research in Europe at the career stage at which they may still be consolidating their own independent research team. The program is aimed at researchers who have completed a doctorate seven to 12 years in the past. Consolidator Grants are awarded by the European Research Council (ERC) as part of the Horizon Europe initiative. Each project receives about two million euros in funding for a five-year term.