BRAIN EAGER: Wireless Measurement of Neuronal Currents Using Spin-Torque Nano-Oscillators

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This award is jointly made by two programs the Instrument Development for Biological Research program (IDBR) and Emerging Frontiers (EF) in the Directorate of Biological Sciences (BIO).The brain is a complex network of interconnected circuits that exchange signals in the form of action potentials. These action potentials hold the key to understanding cognition and complex thought. Currently available non-invasive methods for probing neuronal activity cannot achieve sufficient spatial or temporal resolution to observe individual action potentials from single neurons or small clusters, which is a major limitation. This principal investigator proposes to study a novel approach for non-invasive measurements that will be able to read out individual action potentials across the entire brain. This project will take advantage of recent advances in spintronic devices to create injectable nano-reporters that will detect weak electrical signals in the brain and convert them to microwave signals that can be detected wirelessly outside the body. The detection device to be used is the spin-torque nano-oscillator (STNO), which converts electrical signals into microwave field oscillations that can be detected wirelessly. This approach could ultimately lead to the first non-invasive technology capable of measuring activations of individual neurons and small-scale neuronal networks in live primates and humans. This capability would have a major impact on our understanding of the inner workings of the brain and cognition. It could also have important clinical applications, particularly in the areas of neurological disorders and brain machine interfaces. The ability to monitor neuronal activity at the cellular level non-invasively is crucial for attaining a better understanding of cognition, as well as many clinical applications. Currently, all non-invasive methods for monitoring brain activity cannot simultaneously achieve the spatial and temporal resolution required to sense individual action potentials from a single neuron. This project is a novel approach for non-invasive measurements that will be able to read out individual action potentials across the whole brain from single neurons. To achieve the transduction of electrical activity to microwaves, a nano-sized device called a spin-torque nano-oscillator (STNO) will be used that converts steady electrical signals into microwave frequency magnetic field oscillations that can be detected wirelessly. The STNO responds in microseconds to electric signals, and thus can be directly used to measure individual neuronal action potentials. In addition, the STNO is a nano-scale device and can report on the firing and location of a single neuron. This project represents the first application to neurobiology of the exciting and rapidly evolving field of spintronics. A test system will be developed that includes a neuron simulator (a tunable circuit that simulates the voltages and impedance of a single neuron) and a high sensitivity microwave receiver to demonstrate the ability of these devices to report that activation state of a neuron wirelessly. this project also involves the design, fabrication, and test optimization of STNO devices for neurobiological applications. The ultimate and specific goal of this EAGER project is to perform a proof-of-concept demonstration of the proposed apparatus on a live squid axon.