The number of serious brain disorders and deaths worldwide caused by diseases of the nervous system has risen sharply in recent decades. Despite huge advances in neuroscience over the past century, our understanding of the brain is still far from complete. To understand the causes and to aid the growing number of affected people, we need to be able to study the brain more closely. New tailored sensors measuring small electromagnetic fluctuations produced by active neurons could contribute to rapidly developing treatments for brain disorders.
The BIO-MAG project will design and create small, lightweight and wearable magnetic sensors – with femtotesla sensitivity – that can measure tiny changes in the brain’s magnetic field, and enable neuronal activity in the brain to be mapped at room temperature. This will be achieved through the development of two innovative and complementary types of sensors that together provide the needed range of sensitivity and spatial resolution. Common to both sensor types is that they will be based on atomically thin two-dimensional (2D) materials – an emergent class of materials with outstanding and highly tunable physical properties. NOMAD PI Kristian Sommer Thygesen is responsible for the BIO-MAG materials modelling and design activities related to point defect-based sensors – activities that will benefit greatly from the exascale workflow engine and AI tools developed within NOMAD.
Sensing with imperfections
One type of sensor will be based on atomic-scale defects in 2D materials and will provide picotesla sensitivity with a spatial resolution down to the nanometer scale. The magnetic field–dependent response of such defects is recorded using laser light, which allows for not just high sensitivity in magnetic field, but also in terms of spatial resolution, for instance for mapping single neurons. Using high-throughput density functional theory calculations, thousands of point defects in various 2D host materials will be screened for their magneto-optical properties before the most promising systems will be synthesised and their ability for ultrasensitive magnetic field sensing scrutinized in experiments.
The other type of sensor will be based on the recently discovered Extraordinary Magnetoresistance Effect. Applying magnetic fields to a traditional material can cause significant changes in the resistance, called magnetoresistance. In contrast, extraordinary magnetoresistance is a geometric effect occurring only in heterogenous devices, consisting of for instance of both semiconducting and metallic areas. The magnetic field determines whether the electrons pass through the semiconductor or the metal, and that leads to measurable changes in the resistance. Groundbreaking computer algorithms will calculate the exact shape of the devices, which can boost the magnetic field sensitivity at least 100,000-fold. We will take advantage of atomic-scale calculations on supercomputers to identify which 2D materials host the most magnetically sensitive defects and then attempt to synthesise those exact materials.
Paving the way for non-invasive recordings
To push the limits of detection, we will combine the sensing elements into arrays, to produce real-time maps of neurons in action, with much better sensitivity and resolution than possible today. If we succeed, this will pave the way for non-invasive recording of movies of bundles of neurons in action, up to 1000 frames a second, and with opportunities for rendering 3D images.
Insights obtained using these new sensors will boost our understanding of how the brain perceives, processes and stores information and bridge the gap between fundamental biomagnetic neuroresearch and brain mapping via preclinical magnetoencephalography. This in turn will contribute to more rapid development of treatments for brain disorders and provide a research tool to improve our chances of solving the major unsolved questions in neuroscience, medicine and cognition.
Facts about BIO-MAG
In 2021, the Novo Nordisk Foundation awarded a Challenge Programme grant of 8 million Euro to a team of researchers led by Prof. Nini Pryds from the Technical University of Denmark for the project Ultrasensitive Biomagnetometers with Macro to Nano Resolution (BIO-MAG). This project aims to create small, biocompatible and lightweight magnetic sensors with sensitivity suitable for mapping neuronal activity in living organisms. The ultimate aim is to obtain unprecedented insight into neurons, neural networks and the workings of the human mind. NOMAD PI Kristian Sommer Thygesen is leading the atomic-scale materials modelling activities in BIO-MAG.