Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter September 16, 2019

Optically pumped magnetometers enable a new level of biomagnetic measurements

Tilmann Sander ORCID logo, Anna Jodko-Władzińska ORCID logo, Stefan Hartwig, Rüdiger Brühl and Thomas Middelmann ORCID logo

Abstract

The electrophysiological activities in the human body generate electric and magnetic fields that can be measured noninvasively by electrodes on the skin, or even, not requiring any contact, by magnetometers. This includes the measurement of electrical activity of brain, heart, muscles and nerves that can be measured in vivo and allows to analyze functional processes with high temporal resolution. To measure these extremely small magnetic biosignals, traditionally highly sensitive superconducting quantum-interference devices have been used, together with advanced magnetic shields. Recently, they have been complemented in usability by a new class of sensors, optically pumped magnetometers (OPMs). These quantum sensors offer a high sensitivity without requiring cryogenic temperatures, allowing the design of small and flexible sensors for clinical applications. In this letter, we describe the advantages of these upcoming OPMs in two exemplary applications that were recently carried out at Physikalisch-Technische Bundesanstalt (PTB): (1) magnetocardiography (MCG) recorded during exercise and (2) auditory-evoked fields registered by magnetoencephalography.


Corresponding author: Thomas Middelmann, Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany, E-mail:

Funding source: European Metrology Programme for Innovation and Research (EMPIR)10.13039/100014132

Award Identifier / Grant number: 15HLT03 EARS II

Acknowledgements

The authors are indebted to Lutz Trahms for long lasting support and collaboration.

  1. Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: Financial support from the European Metrology Research Programme (EMPIR, “Health” program, grant no. 15HLT03 EARS II) is gratefully acknowledged. The EMPIR is jointly funded by the EMPIR participating countries within EURAMET and the European Union.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.

References

[1] J. Gross, “Magnetoencephalography in cognitive neuroscience: a primer”, Neuron, vol. 104, p. 189, 2019, https://doi.org/10.1016/j.neuron.2019.07.001.Search in Google Scholar

[2] J. Lant, G. Stroink, B. ten Voorde, B. Horacek, and T. J. Montague, “Complementary nature of electrocardiographic and magnetocardiographic data in patients with ischemic heart disease”, J. Electrocardiol., vol. 23, p. 315, 1990, https://doi.org/10.1016/0022-0736(90)90121-h.Search in Google Scholar

[3] S. Baillet, “Magnetoencephalography for brain electrophysiology and imaging”, Nat. Nurosci., vol. 20, p. 327, 2017, https://doi.org/10.1038/nn.4504.Search in Google Scholar

[4] W. Andrä and H. Nowak, Magnetism in Medicine, 2nd ed, Weinheim, WILEY-VCH, 2007.Search in Google Scholar

[5] VACUUMSCHMELZE (VAC) GmbH & Co. KG, Germany, 2019 [Online]. Available at: https://www.vacuumschmelze.com/_default_upload_bucket/Abschirmkabinen2019-14082019.pdf.Search in Google Scholar

[6] F. Thiel, A. Schnabel, S. Knappe-Grüneberg, D. Stollfuß, and M. Burghoff, “Demagnetization of magnetically shielded rooms”, Rev. Sci. Instrum., vol. 78, 2007, Art no. 035106, https://doi.org/10.1063/1.2713433.Search in Google Scholar

[7] R. Körber, J.-H. Storm, H. Seton, et al., “SQUIDs in biomagnetism: a roadmap towards improved healthcare”, Supercond. Sci. Technol., vol. 29, p. 113001, 2016, https://doi.org/10.1088/0953-2048/29/11/113001.Search in Google Scholar

[8] R. Mhaskar, S. Knappe, and J. Kitching, “A low-power, high-sensitivity micromachined optical magnetometer”, Appl. Phys. Lett., vol. 101, p. 241105, 2012, https://doi.org/10.1063/1.4770361.Search in Google Scholar

[9] I. K. Kominis, T. W. Kornack, J. C. Allred, and M. Romalis, “A subfemtotesla multichannel atomic magnetometer”, Nature, vol. 422, p. 596, 2003, https://doi.org/10.1038/nature01484.Search in Google Scholar

[10] O. Alem, T. H. Sander, R. Mhaskar, et al., “Fetal magnetocardiography measurements with an array of microfabricated optically pumped magnetometers”, Phys. Med. Biol., vol. 60, p. 4797, 2015, https://doi.org/10.1088/0031-9155/60/12/4797.Search in Google Scholar

[11] E. Boto, N. Holmes, J. Leggett, et al., “Moving magnetoencephalography towards real-world applications with a wearable system”, Nature, vol. 555, p. 657, 2018, https://doi.org/10.1038/nature26147.Search in Google Scholar

[12] D. Kimball, F. Jackson, and D. Budker, Optical Magnetometry, New York: Cambridge University Press, 2013.Search in Google Scholar

[13] K. Jensen, P. Kehayias, and D. Budker, “Magnetometry with nitrogen-vacancy centers in diamond”, in High Sensitivity Magnetometers, Smart Sensors, Measurement and Instrumentation, vol. 19, A. Grosz,M. J. Haji-Sheikh, and S. C. Mukhopadhyay, Switzerland, Springer International Publishing, 2017, p. 553.Search in Google Scholar

[14] W. Happer and A. C. Tam, “Effect of rapid spin exchange on the magnetic-resonance spectrum of alkali vapors”, Phys. Rev. A, vol. 16, p. 1877, 1977, https://doi.org/10.1103/physreva.16.1877.Search in Google Scholar

[15] A. P. Colombo, T. R. Carter, A. Borna, et al., “Four-channel optically pumped atomic magnetometer for magnetoencephalography”, Opt. Express, vol. 24, p. 15403, 2016, https://doi.org/10.1364/oe.24.015403.Search in Google Scholar

[16] E. Labyt, M. Corsi, W. Fourcault, et al., “Magnetoencephalography with optically pumped 4He magnetometers at ambient temperature”, IEEE Trans. Med. Imaging, vol. 38, p. 90, 2019, https://doi.org/10.1109/tmi.2018.2856367.Search in Google Scholar

[17] QuSpin Inc., “About Us”, QuSpin Inc., Louisville, Colorado, [Online]. Available at: http://quspin.com/about-us/. [retrieved 2020].Search in Google Scholar

[18] J. Osborne, J. Orton, and O. S. V. Alem, “Fully integrated standalone zero field optically pumped magnetometer for biomagnetism”, in Steep Dispersion Engineering and Opto-Atomic Precision Metrology XI, Bellingham, WA, SPIE, 2018, p. 105481G.Search in Google Scholar

[19] J.-H. Storm, P. Hömmen, D. Drung, and R. Körber, “An ultra-sensitive and wideband magnetometer based on a superconducting quantum interference device”, Appl. Phys. Lett., vol. 110, p. 072603, 2017, https://doi.org/10.1063/1.4976823.Search in Google Scholar

[20] R. M. Hill, E. Boto, M. Rea, et al., “Multi-channel whole-head OPM-MEG: Helmet design and a comparison with a conventional system”, NeuroImage, vol. 219, p. 116995, 2020, https://doi.org/10.1016/j.neuroimage.2020.116995.Search in Google Scholar

[21] C. Koch, “SQUID magnetocardiography: status and perspectives”, IEEE Trans. Appl. Supercon., vol. 11, p. 49, 2001, https://doi.org/10.1109/77.919284.Search in Google Scholar

[22] G. Bison, N. Castagna, A. Hofer, et al., “A room temperature 19-channel magnetic field mapping device for cardiac signals”, Appl. Phys. Lett., vol. 95, p. 173701, 2009, https://doi.org/10.1063/1.3255041.Search in Google Scholar

[23] K. Kamada, Y. Ito, and T. Kobayashi, “Human MCG measurements with a high-sensitivity potassium atomic”, Physio. Meas., vol. 33, p. 1063, 2012, https://doi.org/10.1088/0967-3334/33/6/1063.Search in Google Scholar

[24] P. Takala, H. Hänninen, J. Montonen, et al., “Magnetocardiographic and electrocardiographic exercise mapping in healthy subjects”, Ann. Biomed. Eng., vol. 29, p. 501, 2001, https://doi.org/10.1114/1.1376388.Search in Google Scholar

[25] K. Brockmeier, L. Schmitz, J. D. J. B. Chavez, et al., “Magnetocardiography and 32-lead Potential mapping”, J. Cardiovasc. Electr., vol. 8, p. 615, 1997, https://doi.org/10.1111/j.1540-8167.1997.tb01824.x.Search in Google Scholar

[26] J.-W. Park, B. Leithäuser, M. Vršansky, and F. Jung, “Obutamine stress magnetocardiography for the detection of significant coronary artery stenoses – A prospective study in comparison with simultaneous 12-lead electrocardiography”, Clin. Hemorheol. Micro., vol. 39, p. 21, 2008, https://doi.org/10.3233/ch-2008-1064.Search in Google Scholar

[27] S. Knappe, T. Sander, and L. Trahms, “Optically Pumped Magnetometers for MEG”, in Magnetoencephalography: From Signals to Dynamic Cortical Networks, Berlin, Heidelberg, Springer International Publishing, 2019, p. 1.Search in Google Scholar

[28] P. J. Broser, S. Knappe, D. Kajal, et al., “Optically pumped magnetometers for magneto-myography to study the innervation of the hand”, IEEE Trans. Neur. Syst. Rehabil., vol. 26, p. 2226, 2018, https://doi.org/10.1109/tnsre.2018.2871947.Search in Google Scholar

[29] H. Eswaran, D. Escalona-Vargas, E. H. Bolin, J. D. Wilson, and C. L. Lowery, “Fetal magnetocardiography using optically pumped magnetometers: a more adaptable and less expensive alternative”, Prenat. Diag., vol. 37, p. 193, 2017, https://doi.org/10.1002/pd.4976.Search in Google Scholar

[30] T. M. Tierney, N. Holmes, S. Mellor, et al., “Optically pumped magnetometers: from quantum origins to multi-channel magnetoencephalography”, NeuroImage, vol. 199, p. 598, 2019, https://doi.org/10.1016/j.neuroimage.2019.05.063.Search in Google Scholar

Received: 2020-06-10
Accepted: 2020-08-24
Published Online: 2019-09-16
Published in Print: 2020-11-26

© 2020 Walter de Gruyter GmbH, Berlin/Boston