DARPA aims to develop magnetic field sensing for applications such as brain-machine interfaces for controlling prosthetic limbs through the magnetic signals associated with thought.

DARPA reveals animal magnetism breakthrough

Our own body generates electric currents that create ripples in the surrounding magnetic field.

These magnetic field variations allow medical professionals to use certain diagnostic tools for brain and heart conditions.

But now new research led by DARPA (Defense Advanced Research Projects Agency) aims to go beyond these diagnostic tests and develop magnetic field sensing for broader applications such as brain-machine interfaces (BMIs) for uses such as controlling prosthetic limbs and external machines through the magnetic signals associated with thought.

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The invisible magnetic field lines associated with a bar magnet hints of the far weaker biology-based magnetic fields from hearts and brains that DARPA’s new AMBIIENT program aims to measure with unprecedented ease

The invisible magnetic field lines associated with a bar magnet hints of the far weaker biology-based magnetic fields from hearts and brains that DARPA’s new AMBIIENT program aims to measure with unprecedented ease

DARPA’s new Atomic Magnetometer for Biological Imaging in Earth’s Native Terrain (AMBIIENT) program aims to bring about a new era in which brain imaging such as magnetoencephalography (MEG’s) and heart screening tests such as magnetocardiography (MCGs’) become more practical for a wide range of applications.

However, Earth’s magnetic field has been preventing biomagnetic field sensing techniques from extending beyond its current limitations.

Planet Earth’s average magnetic field is 50 millionth’s of a Tesla – a unit of magnetic field strength named after Nikola Tesla, famous for designing the Tesla coil as a power supply for his system of electric lighting.

Earth’s magnetic field is a million to a billion times stronger than the 10 picoTesla to 10 femtoTesla magnetic fields that originate from human bodies.

In addition to this, even today’s leading magnetic field sensors have a limited dynamic range, meaning they’re unable to respond reliably in the presence of very strong magnetic field strengths – which is the case when biological magnetic fields are found in addition to Earth’s own magnetism.

So without strong shielding, the magnetic signals from life sources would be lost amidst Earth’s strong magnetism – even with the best available sensors.

Research led by DARPA to develop magnetic field sensing could be used for applications including brain-machine interfaces (BMIs) that can control prosthetic limbs and external machines through the magnetic signals associated with thought

Research led by DARPA to develop magnetic field sensing could be used for applications including brain-machine interfaces (BMIs) that can control prosthetic limbs and external machines through the magnetic signals associated with thought

‘Traditionally, measuring small magnetic signals in ambient environments has relied on pairs of high-performance sensors separated by a baseline distance and then measuring the small field-strength differences between the two sensors,’ said Dr Robert Lutwak, AMBIIENT’s program manager in DARPA’s Microsystems Technology Office.

‘This gradiometric technique has worked well for applications in geophysical surveying and unexploded ordnance detection, but due to the combination of the sensors’ limited dynamic range and the natural spatial variation of the background signals, this approach falls several orders of magnitude short of being able to detect biological magnetic signals,’ he said.

So the AMBIIENT program is challenging the research community to devise new types of magnetic sensors that can detect tiny magnetic signals without the need for shielding and with whatever the ambient magnetic field environment might be.

New DARPA technologies could, for example, allow a medic on a battlefield to wave a wandlike sensor to quickly screen a warfighter for signs of concussion of other head trauma written in the brain's subtle magnetic fields

New DARPA technologies could, for example, allow a medic on a battlefield to wave a wandlike sensor to quickly screen a warfighter for signs of concussion of other head trauma written in the brain’s subtle magnetic fields

Such technologies could, for example, could allow a medic on a battlefield to wave a wandlike sensor to quickly screen a warfighter for signs of concussion of other head trauma written in the brain’s subtle magnetic fields.

One approach that AMBIIENT researchers may look into is to monitor changes in the polarization or other measurable features of a small laser beam as it passes through vapor cells that have atoms that respond in laser-beam-altering ways to very small magnetic fields.

Monitoring changes in the laser light’s features would open a new and practical window on magnetic fields that were previously unmeasurable under ambient conditions.

Such technologies could, for example, could allow a medic on a battlefield to wave a wandlike sensor to quickly screen a warfighter for signs of concussion of other head trauma written in the brain’s subtle magnetic fields.

Dr Robert Lutwak, AMBIIENT’s program manager, envisions uncommon applications of magnetic field sensing, including magnetic navigation (MagNav) as a backup, alternative, or supplement to GPS-based navigation

Dr Robert Lutwak, AMBIIENT’s program manager, envisions uncommon applications of magnetic field sensing, including magnetic navigation (MagNav) as a backup, alternative, or supplement to GPS-based navigation

‘High sensitivity magnetic sensing and imaging will offer a powerful new tool for medical research and clinical diagnosis of neurological and cardiac activity,’ said Dr Lutwak.

‘DARPA’s goal is to end up with the capability of high-sensitivity magnetic sensing in a low-cost device that can operate in common environments,’ he said.

Dr Lutwak also also envisions some uncommon applications of magnetic field sensing, including magnetic navigation (MagNav) as a backup, alternative, or supplement to GPS-based navigation.

Equipped with the kind of sensors that could be developed in the AMBIIENT program, an aircraft coasting at airliner altitudes might be able to keep track of the well-mapped magnetic field variations at the Earth’s surface for determining its over-ground location within about 250 meters.

DARPA will host a Proposers Day in support of the AMBIIENT program from 9:00 AM to 5:00 PM EDT on April 3, 2017, at the DARPA Conference Center in Arlington, VA

HOW DOES A LIQUID IRON CORE CREATE A MAGNETIC FIELD?

Our planet’s magnetic field is believed to be generated deep down in the Earth’s core.

Nobody has ever journeyed to the centre of the Earth, but by studying shockwaves from earthquakes, physicists have been able to work out its likely structure.

At the heart of the Earth is a solid inner core, two thirds of the size of the moon, made mainly of iron.

At 5,700°C, this iron is as hot as the Sun’s surface, but the crushing pressure caused by gravity prevents it from becoming liquid.

Surrounding this is the outer core there is a 1,242 mile (2,000 km) thick layer of iron, nickel, and small quantities of other metals.

The metal here is fluid, because of the lower pressure than the inner core.

Differences in temperature, pressure and composition in the outer core cause convection currents in the molten metal as cool, dense matter sinks and warm matter rises.

The ‘Coriolis’ force, caused by the Earth’s spin, also causes swirling whirlpools.

This flow of liquid iron generates electric currents, which in turn create magnetic fields.

Charged metals passing through these fields go on to create electric currents of their own, and so the cycle continues. This self-sustaining loop is known as the geodynamo.

The spiralling caused by the Coriolis force means the separate magnetic fields are roughly aligned in the same direction, their combined effect adding up to produce one vast magnetic field engulfing the planet.

Posted on; DailyMail>>

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