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Dmitry Budker - One of the best experts on this subject based on the ideXlab platform.

  • Action potentials induce biomagnetic fields in Venus flytrap plants
    2020
    Co-Authors: Anne Fabricant, Geoffrey Iwata, Sönke Scherzer, Lykourgos Bougas, Katharina Rolfs, Anna Jodko-władzińska, Jens Voigt, Rainer Hedrich, Dmitry Budker
    Abstract:

    Upon stimulation, plants elicit electrical signals that can travel within a cellular network analogous to the animal nervous system. It is well-known that in the human brain, voltage changes in certain regions result from concerted electrical activity which, in the form of action potentials (APs), travels within nerve-cell arrays. Electrophysiological techniques like electroencephalography, magnetoencephalography, and magnetic resonance imaging are used to record this activity and to diagnose disorders. In the plant kingdom, two types of electrical signals are observed: all-or-nothing APs of similar amplitudes to those seen in humans and animals, and slow-wave potentials of smaller amplitudes. Sharp APs appear restricted to unique plant species like the "sensitive plant", Mimosa pudica, and the carnivorous Venus flytrap, Dionaea muscipula. Here we ask the question, is electrical activity in the Venus flytrap accompanied by distinct magnetic signals? Using atomic optically pumped magnetometers, Biomagnetism in AP-firing traps of the carnivorous plant was recorded. APs were induced by heat stimulation, and the thermal properties of ion channels underlying the AP were studied. The measured magnetic signals exhibit similar temporal behavior and shape to the fast de- and repolarization AP phases. Our findings pave the way to understanding the molecular basis of Biomagnetism, which might be used to improve magnetometer-based noninvasive diagnostics of plant stress and disease.

  • Search for plant Biomagnetism with a sensitive atomic magnetometer
    Journal of Applied Physics, 2011
    Co-Authors: Eric Corsini, Victor M. Acosta, Nicholas Baddour, James M. Higbie, Brian Lester, Paul Licht, Brian Patton, Mark Prouty, Dmitry Budker
    Abstract:

    We report what we believe is the first experimental limit placed on plant Biomagnetism. Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence, known for its fast biochemical processes while blooming. We find that the magnetic field from these processes, projected along the Earth’s magnetic field, and measured at the surface of the plant, is ≲ 0.6 μG.

  • search for plant Biomagnetism with a sensitive atomic magnetometer
    arXiv: Atomic Physics, 2010
    Co-Authors: Eric Corsini, Victor M. Acosta, Nicholas Baddour, James M. Higbie, Brian Lester, Paul Licht, Brian Patton, Mark Prouty, Dmitry Budker
    Abstract:

    We report what we believe is the first experimental limit placed on plant Biomagnetism. Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence, known for its fast bio-chemical processes while blooming. We find that the surface magnetic field from these processes, projected along the Earth's magnetic field, and measured at the surface of the plant, is less then ~0.6uG.

C N Guy - One of the best experts on this subject based on the ideXlab platform.

Alex I. Braginski - One of the best experts on this subject based on the ideXlab platform.

  • Biomagnetism using SQUIDs: status and perspectives
    Superconductor Science and Technology, 2006
    Co-Authors: Karsten Sternickel, Alex I. Braginski
    Abstract:

    Biomagnetism involves the measurement and analysis of very weak local magnetic fields of living organisms and various organs in humans. Such fields can be of physiological origin or due to magnetic impurities or markers. This paper reviews existing and prospective applications of Biomagnetism in clinical research and medical diagnostics. Currently, such applications require sensitive magnetic SQUID sensors and amplifiers. The practicality of biomagnetic methods depends especially on techniques for suppressing the dominant environmental electromagnetic noise, and on suitable nearly real-time data processing and interpretation methods. Of the many biomagnetic methods and applications, only the functional studies of the human brain (magnetoencephalography) and liver susceptometry are in clinical use, while functional diagnostics of the human heart (magnetocardiography) approaches the threshold of clinical acceptance. Particularly promising for the future is the ongoing research into low-field magnetic resonance anatomical imaging using SQUIDs.

Vittorio Pizzella - One of the best experts on this subject based on the ideXlab platform.

  • Biomagnetism: an application of superconductivity
    Superconductor Science and Technology, 1992
    Co-Authors: P Carelli, Vittorio Pizzella
    Abstract:

    Describes the biomagnetic method, introducing the basic physical concepts, the measuring devices and some significant results obtained in the measurement of magnetic fields of the human body. Special importance is given to the actual problems that must be faced in detecting biomagnetic fields, and to the present technology of multichannel detectors. Special importance is also given to the applications, which are providing significant progress in clinical investigations.

Hui Dong - One of the best experts on this subject based on the ideXlab platform.

  • SQUIDs in Biomagnetism: a roadmap towards improved healthcare
    Superconductor Science and Technology, 2016
    Co-Authors: Rainer Körber, Jan Hendrik Storm, H.c. Seton, Jyrki P. Mäkelä, Ritva Paetau, Lauri Parkkonen, Christoph Pfeiffer, Bushra Riaz, Justin F. Schneiderman, Hui Dong
    Abstract:

    Globally, the demand for improved health care delivery while managing escalating costs is a major challenge. Measuring the biomagnetic fields that emanate from the human brain already impacts the treatment of epilepsy, brain tumours and other brain disorders. This roadmap explores how superconducting technologies are poised to impact health care. Biomagnetism is the study of magnetic fields of biological origin. Biomagnetic fields are typically very weak, often in the femtotesla range, making their measurement challenging. The earliest in vivo human measurements were made with room-temperature coils. In 1963, Baule and McFee (1963 Am. Heart J. 55 95-6) reported the magnetic field produced by electric currents in the heart ('magnetocardiography'), and in 1968, Cohen (1968 Science 161 784-6) described the magnetic field generated by alpha-rhythm currents in the brain ('magnetoencephalography'). Subsequently, in 1970, Cohen et al (1970 Appl. Phys. Lett. 16 278-80) reported the recording of a magnetocardiogram using a Superconducting QUantum Interference Device (SQUID). Just two years later, in 1972, Cohen (1972 Science 175 664-6) described the use of a SQUID in magnetoencephalography. These last two papers set the scene for applications of SQUIDs in Biomagnetism, the subject of this roadmap. The SQUID is a combination of two fundamental properties of superconductors. The first is flux quantization - the fact that the magnetic flux ? in a closed superconducting loop is quantized in units of the magnetic flux quantum, ?0 ? h/2e, ? 2.07 × 10-15 Tm2 (Deaver and Fairbank 1961 Phys. Rev. Lett. 7 43-6, Doll R and Nabauer M 1961 Phys. Rev. Lett. 7 51-2). Here, h is the Planck constant and e the elementary charge. The second property is the Josephson effect, predicted in 1962 by Josephson (1962 Phys. Lett. 1 251-3) and observed by Anderson and Rowell (1963 Phys. Rev. Lett. 10 230-2) in 1963. The Josephson junction consists of two weakly coupled superconductors separated by a tunnel barrier or other weak link. A tiny electric current is able to flow between the superconductors as a supercurrent, without developing a voltage across them. At currents above the 'critical current' (maximum supercurrent), however, a voltage is developed. In 1964, Jaklevic et al (1964 Phys. Rev. Lett. 12 159-60) observed quantum interference between two Josephson junctions connected in series on a superconducting loop, giving birth to the dc SQUID. The essential property of the SQUID is that a steady increase in the magnetic flux threading the loop causes the critical current to oscillate with a period of one flux quantum. In today's SQUIDs, using conventional semiconductor readout electronics, one can typically detect a change in ? corresponding to 10-6 ?0 in one second. Although early practical SQUIDs were usually made from bulk superconductors, for example, niobium or Pb-Sn solder blobs, today's devices are invariably made from thin superconducting films patterned with photolithography or even electron lithography. An extensive description of SQUIDs and their applications can be found in the SQUID Handbooks (Clarke and Braginski 2004 Fundamentals and Technology of SQUIDs and SQUID Systems vol I (Weinheim, Germany: Wiley-VCH), Clarke and Braginski 2006 Applications of SQUIDs and SQUID Systems vol II (Weinheim, Germany: Wiley-VCH)). The roadmap begins (chapter 1) with a brief review of the state-of-the-art of SQUID-based magnetometers and gradiometers for biomagnetic measurements. The magnetic field noise referred to the pick-up loop is typically a few fT Hz-1/2, often limited by noise in the metallized thermal insulation of the dewar rather than by intrinsic SQUID noise. The authors describe a pathway to achieve an intrinsic magnetic field noise as low as 0.1 fT Hz-1/2, approximately the Nyquist noise of the human body. They also descibe a technology to defeat dewar noise. Chapter 2 reviews the neuroscientific and clinical use of magnetoencephalography (MEG), by far the most widespread application of Biomagnetism with systems containing typically 300 sensors cooled to liquid-helium temperature, 4.2 K. Two important clinical applications are presurgical mapping of focal epilepsy and of eloquent cortex in brain-tumor patients. Reducing the sensor-to-brain separation and the system noise level would both improve spatial resolution. The very recent commercial innovation that replaces the need for frequent manual transfer of liquid helium with an automated system that collects and liquefies the gas and transfers the liquid to the dewar will make MEG systems more accessible. [...]