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TDK Reports Preliminary Study Results for Measurement and Visualization of Cardiac Activity Using Prototype MR Sensors

  • In a feasibility study using TDK’s prototype high-sensitivity magnetoresistive (MR) elements, TDK was able to perform the first* magnetic field distribution measurement of a human heart. Visualization of the cardiac magnetic field distribution of five healthy subjects was demonstrated with a prototype 30-channel sensor array. This study represents one aspect of TDK’s advanced research into magnetic sensors, a growth area in which TDK is currently bolstering its efforts.

Jun. 7, 2016

TDK Corporation collaborated with the Joint Research Department of Advanced Medical Technology and the Department of Cardiovascular Medicine (Specialty of Cardiac Electrophysiology) at the Graduate School of Medical and Dental Sciences of Tokyo Medical and Dental University (TMDU) to perform a feasibility study using TDK’s prototype high-sensitivity magnetoresistive (MR) elements. During the study, the prototype magnetic sensors based on high-sensitivity MR elements developed by TDK were used to visualize the magnetic field distribution in the heart by measuring the magnetic fields generated by the hearts of five healthy subjects using a 30-channel sensor array. This is the first reported achievement of magnetic field distribution measurement of the heart in humans. However, further research and development are required before these prototype sensors may be commercialized for clinical use.

TDK is currently accelerating the expansion of a range of strategic growth products as part of its growth strategy geared towards the IoT market. TDK considers sensors, in particular, to be a growth product area that will see expansion in all of TDK’s key market areas: Automotive, Information and Communications Technology, industrial, and energy markets. Magnetic sensors, which make use of the magnetic materials technologies in which TDK specializes, constitute the central focus of this strategic initiative, and TDK is proactively engaged in the development of such cutting-edge sensors. In this collaborative feasibility study, TDK was able to achieve a world first in measurement results obtained using prototype MR elements. MR elements are widely used in the magnetic heads of hard disk drives, an area of expertise in which TDK has been a world-leading pioneer in achieving higher density in such devices.

Measuring extremely weak and subtle magnetic fields—such as biomagnetic fields—has previously involved the use of superconducting quantum interference device (SQUID) sensors, which require cooling by liquid helium. Because such devices require large-scale equipment and facilities, use of these sensors has been limited to only a portion of research institutions. Now, however, the magnetic field distribution of a human heart, one example of a biomagnetic field, has been visualized in a feasibility study using TDK’s prototype magnetic sensor technology. This is a world first involving a prototype MR sensor array used at room temperature. However, further research and development are required before these prototype sensors may be commercialized for clinical use.

This prototype sensor technology is also being designed to facilitate easy measurement by parallel linkage of multiple room-temperature sensors. The sensors are being designed and developed to allow for higher-density measurement, to help enable the identification of initial location of cardiac activity. If successful, this type of measurement also may facilitate the measurement and evaluation of the spread of activity to other parts of the organ.

These prototype room-temperature sensors are also being developed to enable device portability, which is anticipated to facilitate easier, more casual diagnosis of cardiac diseases in the future. The sensors may also be developed and studied for additional indications, which may include use in the diagnosis of muscular and neurological diseases, and in rehabilitation and sports training applications.

Details and results of this feasibility study was presented formally at the 31st Annual Meeting of Japan Biomagnetism and Bioelectromagnetics Society, held at the Kanazawa Bunka Hall in Ishikawa, Japan, on June 9 and 10, 2016.

Building on the positive results of this joint research, TDK will continue to accelerate the pace of its research and development in the magnetic sensor field, one which will be a core pillar of its operations in the future.

  • *As of May 2016, according to TDK data

  • Magnetoresistive element: An element that changes its electrical resistance according to the magnetic field applied to it. Such elements enable the detection of magnetism.
  • Magnetic field distribution: The spatial distribution of the directionality and strength of a magnetic field. Here, it refers to the two-dimensional distribution within the plane of a sensor array.
  • Biomagnetism: Magnetic fields generated by the electrical activity of living biological organisms. It is observed in organs such as the heart, brain, nerves, and muscles.
  • Cardiac activity: Activity of the muscles that make up the heart (i.e., cardiac) organ.
  • Muscular diseases: A collective term for diseases in which muscles suffer a loss in strength or undergo atrophy due to muscle-related abnormalities. Examples include muscular dystrophy, myositis, and myasthenia gravis.
  • Neurological diseases: A collective term for diseases that cause disorders of the brain, spinal cord, peripheral nerves, etc. The term covers a wide range of diseases, including amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), cervical disc hernia (CDH), Guillain-Barré syndrome (GBS), diabetic neuropathy (DN), and peripheral entrapment neuropathy.
About Tokyo Medical and Dental University

Tokyo Medical and Dental University (TMDU) is the only comprehensive medical university in Japan that has both undergraduate and graduate programs in medicine and dentistry. The undergraduate programs are offered through the Faculties of Medicine and Dentistry and prepare students to be medical or dental professionals. Our graduate programs in Medical and Dental Sciences and Health Sciences produce leaders who go into research (basic research and clinical research), education, or a combination of such work. Many professors teach and conduct cutting-edge research in their respective Faculty or at one of our specialized research institutes, such as the Medical Research Institute or the Institute of Biomaterials and Bioengineering.

About TDK Corporation

TDK Corporation is a leading electronics company based in Tokyo, Japan. It was established in 1935 to commercialize ferrite, a key material in electronic and magnetic products. TDK’s portfolio includes electronic components, modules and systems** marketed under the product brands TDK and EPCOS, power supplies, magnetic application products, as well as energy devices, flash memory application devices, and others. TDK focuses on demanding markets in the areas of information and communication technology and consumer, automotive, and industrial electronics. The company has a network of design and manufacturing locations and sales offices in Asia, Europe, and in North and South America. In fiscal 2016, TDK posted total sales of USD 10.2 billion and employed about 92,000 people worldwide.

  • ** The product portfolio includes ceramic, aluminum electrolytic and film capacitors, ferrites, inductors, high-frequency components such as surface acoustic wave (SAW) filter products and modules, piezo and protection components, and sensors.
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