Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers at Kiel University develop extremely sensitive sensor system for magnetic fields

15.02.2018

In the future, highly-sensitive sensors could be able to detect magnetic signals from the body in order to draw conclusions on heart or brain functions. In contrast with established electrical measurement techniques, they would achieve contactless measurement, i.e. without direct skin contact. At present, such measurements are still associated with considerable expense and effort. Now, researchers at Kiel University built an important basis for biomagnetic diagnostics. The interdisciplinary research team developed a magnetic field sensor system that not only includes the detection of a magnetic signal, but also its processing. They presented their results in the journal Scientific Reports.

In the future, highly-sensitive sensors could be able to detect magnetic signals from the body in order to draw conclusions on heart or brain functions. In contrast with established electrical measurement techniques, they would achieve contactless measurement, i.e. without direct skin contact. At present, such measurements are still associated with considerable expense and effort. This is because the sensors must be cooled dramatically, or shielded against other magnetic fields.


Every sensor is only as good as the measuring system in which it is integrated. The members of the CRC described a complete measuring system for the first time - from the sensor to the electronic components - for reading and processing signals.

Photo: Siekmann/CAU


The developed surface acoustic wave sensor is made with a magnetostrictive thin film (b). If a magnetic field occurs, its elastic properties change. It lies on top of a piezoelectric substrate (d), which converts the electric potential of the electrodes (c) into a mechanical pressure into an electrical voltage. The generated acoustic waves spread along the transparent guiding layer (a).

Image: CRC 1261

Now, researchers at Kiel University built an important basis for biomagnetic diagnostics. In the Collaborative Research Center (CRC) 1261 "Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics", they are researching the development of magnetic field sensors, which in the long-term - with better spatial resolution - could be easily put to use in medical practice.

The interdisciplinary research team developed a magnetic field sensor system that not only includes the detection of a magnetic signal, but also its processing. The researchers presented their results in the journal Scientific Reports.

Some diagnoses, such as a suspected heart attack, must be performed quickly. The heart activity can be checked with an electrocardiogram (ECG), for example, where electrodes stuck directly onto the skin measure the electrical signals generated by the heart. Magnetic measurements could one day be much simpler. “In emergencies, or for long-term studies, they offer the advantage of contactless operation," explained Professor Eckhard Quandt, spokesperson for the CRC 1261.

The members of the interdisciplinary research network at Kiel University research and develop various materials and the required electronics for use in magnetic field sensors. "The electrical conductivity of the body also differs in various places, whereas magnetic signals are equally good everywhere," added Quandt, emphasising another advantage of magnetic diagnostics. "In this way, more accurate measurements are possible, with a better spatial resolution." In principle, sensors could thus be moved during the measurement, and signal changes precisely localised.

Although there are already sensors that can measure the biomagnetic signals of the body, they only work with superconducting materials. This means that the ambient temperature must be cooled to -197 degrees Celsius, which requires special equipment and is associated with high costs. Therefore, researchers from electrical engineering, physics, materials science and medicine are working closely together in the CRC 1261 to develop magnetic field sensors which can be used at room temperature in medical practice.

They have now been able to establish an important basis for this: on the one hand, they developed a surface acoustic wave or SAW sensor. On the other hand, they described the required electronic measuring system, into which it is integrated. Obtaining a meaningful measurement result also depends on how the recorded signals are processed and read.

The researchers at the Competence Center Nanosystem Technology at Kiel University produced the SAW sensor using thin-film technology, lithography and etching processes. The key element is a special magnetic material, which is magnetostrictive, i.e. it responds to magnetic fields, in that its elastic properties change and it becomes softer. "We send sound waves along the surface of the sensor. If a magnetic field occurs, the waves slow down in the magnetic material," explained Anne Kittmann, a doctoral researcher in materials science at the CRC. The change in speed indicates how strong the magnetic field is. “It is similar with railway tracks: if you place your ear directly on the rail, you can hear an oncoming train earlier. The sound travels faster in the metal than in the air."

The biggest challenge in sensor development is interference from other magnetic fields. "Biomagnetic signals are extremely weak. Even the earth’s magnetic field affects their measurement," said Kittmann. Therefore, the sensors have so far been used in measuring chambers, which shield against external magnetic fields. But that is neither practical, nor does it protect against disturbances within the chambers. "Because every electrical component of the measuring system superimposes the magnetic signal with additional noise, i.e. its own interference," added Phillip Durdaut, a doctoral researcher in electrical engineering at the CRC. Together with his colleagues, he was able to optimise the interaction of the individual electronic components, so that their noise is negligible.

However, before biomagnetic sensors such as that of the Kiel CRC can be used in medical practice, they must become smaller and more sensitive, for example by modifying the sensor structure, or using additional methods of signal processing. The long-term goal of the researchers is to be able to measure a magnetic field strength in the picotesla to femtotesla range (one trillionth of a tesla). CRC spokesperson Quandt is confident: "The enormous potential of this project lies in the close cooperation of different disciplines and working groups. We can establish important foundations to make magnetic field sensors the long-term standard for cardiological and neurological diagnostics."

The findings are also very promising because of the broad frequency ranges of magnetic signals, which makes them potentially useful for other magnetic field sensing applications, e.g. as current sensors for electric mobility.

Original publication:
Wide Band Low Noise Love Wave Magnetic Field Sensor System. Anne Kittmann, Phillip Durdaut, Sebastian Zabel, Jens Reermann, Julius Schmalz, Benjamin Spetzler, Dirk Meyners, Nian X. Sun, Jeffrey McCord, Martina Gerken, Gerhard Schmidt, Michael Höft, Reinhard Knöchel, Franz Faupel & Eckhard Quandt. Scientific Reports, volume 8, Article number: 278 (2018) doi:10.1038/s41598-017-18441-4
http://www.nature.com/articles/s41598-017-18441-4

Photos are available to download:
http://www.uni-kiel.de/download/pm/2018/2018-036-1.jpg
The silver, shiny magnetic field sensors developed by CRC 1261 researchers in Kiel are 19 mm long and 4 mm wide. However, they must become even smaller and more sensitive for medical use.
Photo: Siekmann/CAU

http://www.uni-kiel.de/download/pm/2018/2018-036-2.jpg
The CRC doctoral researchers (from the left) Phillip Durdaut, Benjamin Spetzler and Anne Kittmann analyse the electrical properties of a sample on a network analyser.
Photo: Siekmann/CAU

http://www.uni-kiel.de/download/pm/2018/2018-036-3.jpg
Every sensor is only as good as the measuring system in which it is integrated. The members of the CRC described a complete measuring system for the first time - from the sensor to the electronic components - for reading and processing signals.
Photo: Siekmann/CAU

http://www.uni-kiel.de/download/pm/2018/2018-036-4.jpg
The developed surface acoustic wave sensor is made with a magnetostrictive thin film (b). If a magnetic field occurs, its elastic properties change. It lies on top of a piezoelectric substrate (d), which converts the electric potential of the electrodes (c) into a mechanical pressure into an electrical voltage. The generated acoustic waves spread along the transparent guiding layer (a).
Image: CRC 1261

Contact:
Professor Dr.-Ing. Eckhard Quandt
Inorganic Functional Materials working group
Spokesperson for the CRC 1261 "Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics"
Tel. +49 (0) 431 880 6200
E-mail: eq@tf.uni-kiel.de

M.Sc. Anne Kittmann
Tel. +49 (0) 431 880 6212
E-mail: anki@tf.uni-kiel.de

Weitere Informationen:

http://www.sfb1261.de
http://www.kompetenzzentrum-nanosystemtechnik.uni-kiel.de/de

Dr. Boris Pawlowski | idw - Informationsdienst Wissenschaft

More articles from Power and Electrical Engineering:

nachricht Nano-scale process may speed arrival of cheaper hi-tech products
09.11.2018 | University of Edinburgh

nachricht Nuclear fusion: wrestling with burning questions on the control of 'burning plasmas'
25.10.2018 | Lehigh University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>