Detect a weak magnetic field measuring only

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of the surrounding strong geomagnetic field.

Weak magnetic fields generated by various things including human comprise valuable information.
The new TDK MR sensor, Nivio xMR sensor, will detect extremely weak magnetic fields. What so far was possible only with highly complex equipment installed in some laboratories, namely to precisely measure fields on the order of one hundred-millionth part of geomagnetism, has now become feasible with much less effort.

Different magnetic sensors and their measuring ranges

Different magnetic sensors and their measuring ranges


Compact sensor detects extremely weak magnetic fields with high resolution

Approaching a noise density of 3pT/√Hz@1Hz which so far was only possible with an expensive and large-scale superconducting quantum interference device (SQUID) magnetometer requiring cryogenic cooling, the TDK sensor measures only 12 x 12 x 74 mm and is designed to work at   room temperature. Inherent noise from the sensor element and associated circuitry is kept to an absolute minimum. This has resulted in a drastic S / N ratio improvement, which is currently being developed and investigated to enable magnetic resolution on the order required for measuring the cardiac magnetic field distribution in real time.


Excellent operability and portability in the geomagnetic field

Support for a dynamic range of ±60 μT (Microtesla) enables measurements within the geomagnetic field, eliminating the need for elaborate equipment configurations. Because shielding and other measures are no longer required, ease of operation and portability can be easily realized. In addition, by using an active magnetic shield to block external environmental noise, it is possible to acquire a weak magnetic field within the geomagnetic environment. This is currently being developed and investigated to allow measurement of cardiac and muscle magnetic fields, a useful capability for example in the areas of healthcare and sports science. With the help of detailed and objective data, effective health maintenance and skills improvement programs can be developed.


High detection sensitivity even when there are obstructions between the sensor and the target

Due to the physical properties of the magnetic field, high-sensitivity measurement is possible even if there are obstacles between the sensor and the measurement target, such as water or oil, copper or aluminum boards, sand or similar. For example, the Nivio xMR sensor is currently being developed and investigated to measure the cardiac magnetic field completely non-invasively while wearing clothes. By utilizing the unique features of weak magnetic field measurement, it is possible to assess the state of an object contained within another object

Easily realize measurement with high accuracy on a research laboratory level

The high-sensitivity magnetic sensor currently being developed and investigated features small dimensions, low cost, and room temperature operation capability allowing measurement of a type previously only possible in a research laboratory. With the Nivio xMR sensor, the application scope for such measurements widens dramatically. This may include for example small-scale medical institutions which may be able to accurately assess the health state of more patients.
Furthermore, it is not only humans for whom important information is contained in weak magnetic field fluctuations, but also objects and natural environments. Magnetic field measurements with formerly unavailable high sensitivity will become possible also in applications besides medical and wellness, such as detection of metal foreign objects and mineral exploration. Depending on the application, the new sensor has the potential to trigger problem-solving innovations in various fields.

Compact dimensions and high sensitivity made possible by TDK
‒ the magnetic materials pioneer

Through its engagement in the manufacture of magnetic heads for hard disk drives (HDD), TDK has continuously played a leading role in the development of magnetoresistance (MR) element technology based on the spintronics approach. The Nivio xMR sensor is a product that applies highly sophisticated MR element technology to achieve very compact dimensions and high sensitivity. Super-precise control of the MR element characteristics, along with innovative element structure design enables the sensor to detect even ultra-weak magnetic fields. The future looks bright for the Nivio xMR sensor which brings measurement of ultra-weak magnetic fields on the Picotesla order (a hundred-millionth part of the geomagnetic field) within easy reach.