Program Summary
State-of-the-art magnetometers are used for diverse civilian and DoD applications, among them biomedical imaging, navigation, and detecting unexploded ordnance and underwater and underground anomalies. Commercially available magnetometers range from inexpensive Hall probes to highly sensitive fluxgate and atomic magnetometers to high-precision Superconducting Quantum Interference Device (SQUID) and Spin Exchange Relaxation Free (SERF) magnetometers. These devices generally have limited dynamic range: the lower-performing devices operate comfortably in the background ambient field of the Earth, while the highest performing sensors only operate in highly shielded, expensive, special-purpose laboratory facilities.
The goal of the Atomic Magnetometer for Biological Imaging in Earth’s Native Terrain (AMBIIENT) program is to develop novel gradient magnetic sensors that can detect biological signals while operating outside of specialized facilities and in the noisy ambient field of the Earth.
A successful AMBIIENT program will lead to sensors that offer a unique capability for dynamic imaging of biological processes with extensive applications in both biomedical research and clinical diagnosis, including magnetoencephalography and magnetocardiography. Recent studies have demonstrated emerging applications in spinal signal detection, diagnosis of mild Traumatic Brain Injury, and in Brain-Machine Interfaces.
The AMBIIENT program seeks to develop next-generation sensors that directly measure magnetic field gradients over short distances rather than subtracting magnetic signals from two separate total field magnetometers. Such sensors would produce a signal that is directly proportional to the magnetic field gradient, thereby providing high common mode rejection without requiring extraordinarily high dynamic range in each sensor. The success of AMBIIENT requires invention and development of novel physics-based techniques and sensor architectures that directly measure magnetic field gradient rather than total field.