Described in Applied Physics Letters,* the study is the first to be performed under conditions resembling a clinical setting with the NIST mini-sensors, which until now have been operated mostly in physics laboratories.
The new experiments were carried out at the Physikalisch Technische Bundesanstalt (PTB) in Berlin, Germany, in a building described as having the world's best magnetic shielding—necessary to block the Earth's magnetic field and other external sources from interfering with the high-precision measurements. PTB has an ongoing program in biomagnetic imaging using human subjects.
The NIST sensor—a tiny container of about 100 billion rubidium atoms in gas form, a low-power infrared laser, and optics—measured the heart's magnetic signature in picoteslas (trillionths of a tesla). The tesla is the unit that defines magnetic field strength. For comparison, the Earth's magnetic field is a million times stronger (measured in millionths of a tesla) than a heartbeat, and an MRI machine uses fields several million times stronger still (operating at several tesla).
In the experiments at PTB, the NIST sensor was placed 5 millimeters above the left chest of a person lying face up on a bed. The sensor successfully detected the weak but regular magnetic pattern of the heartbeat. The same signals were recorded using the "gold standard" for magnetic measurements, a SQUID (superconducting quantum interference device). A comparison of the signals confirmed that the NIST mini-sensor correctly measured the heartbeat and identified many typical signal features. The NIST mini-sensor generates more "noise" (interference) in the signal but has the advantage of operating at room temperature, whereas SQUIDs work best at minus 269 degrees Celsius and require more complicated and expensive supporting apparatus.
A spin-off of NIST's miniature atomic clocks, NIST's magnetic mini-sensors were first developed in 2004. Recently, they were packaged with fiber optics for detecting the light signals that register magnetic field strength. (See the 2007 NIST news release "New NIST Mini-Sensor May Have Biomedical and Security Applications" at http://www.nist.gov/public_affairs/releases/magnetometer.cfm.) In addition, the control system has been reduced in size, so the entire apparatus can be transported easily to other laboratories.
The new results suggest that NIST mini-sensors could be used to make magnetocardiograms, a supplement or alternative to electrocardiograms. The study also demonstrated for the first time that atomic magnetometers can offer sensing stability lasting tens of seconds, as needed for an emerging technique called magnetorelaxometry (MRX), which measures the magnetization decay of magnetic nanoparticles. MRX is used to localize, quantify and image magnetic nanoparticles inserted into biological tissue for medical applications such as targeted drug treatments. Further tests of the NIST sensors at PTB are planned.
* S. Knappe, T.H. Sander, O. Kosch, F. Wiekhorst, J. Kitching and L. Trahms. Cross-validation of microfabricated atomic magnetometers with SQUIDs for biomagnetic applications. Applied Physics Letters. 97, 133703 (2010); doi:10.1063/1.3491548. Online publication: Sept. 28, 2010.
Laura Ost | EurekAlert!
First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester
Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy