{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T07:37:23Z","timestamp":1780472243915,"version":"3.54.1"},"reference-count":57,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2020,8,14]],"date-time":"2020-08-14T00:00:00Z","timestamp":1597363200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004421","name":"Politechnika Warszawska","doi-asserted-by":"publisher","award":["504\/02145\/1142"],"award-info":[{"award-number":["504\/02145\/1142"]}],"id":[{"id":"10.13039\/501100004421","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Magnetography with superconducting quantum interference device (SQUID) sensor arrays is a well-established technique for measuring subtle magnetic fields generated by physiological phenomena in the human body. Unfortunately, the SQUID-based systems have some limitations related to the need to cool them down with liquid helium. The room-temperature alternatives for SQUIDs are optically pumped magnetometers (OPM) operating in spin exchange relaxation-free (SERF) regime, which require a very low ambient magnetic field. The most common two-layer magnetically shielded rooms (MSR) with residual magnetic field of 50 nT may not be sufficiently magnetically attenuated and additional compensation of external magnetic field is required. A cost-efficient compensation system based on square Helmholtz coils was designed and successfully used for preliminary measurements with commercially available zero-field OPM. The presented setup can reduce the static ambient magnetic field inside a magnetically shielded room, which improves the usability of OPMs by providing a proper environment for them to operate, independent of initial conditions in MSR.<\/jats:p>","DOI":"10.3390\/s20164563","type":"journal-article","created":{"date-parts":[[2020,8,14]],"date-time":"2020-08-14T08:28:35Z","timestamp":1597393715000},"page":"4563","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":67,"title":["Compensation System for Biomagnetic Measurements with Optically Pumped Magnetometers inside a Magnetically Shielded Room"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5856-2872","authenticated-orcid":false,"given":"Anna","family":"Jodko-W\u0142adzi\u0144ska","sequence":"first","affiliation":[{"name":"Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0531-8563","authenticated-orcid":false,"given":"Krzysztof","family":"Wildner","sequence":"additional","affiliation":[{"name":"Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8185-8700","authenticated-orcid":false,"given":"Tadeusz","family":"Pa\u0142ko","sequence":"additional","affiliation":[{"name":"Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6986-251X","authenticated-orcid":false,"given":"Micha\u0142","family":"W\u0142adzi\u0144ski","sequence":"additional","affiliation":[{"name":"Warsaw University of Technology, Faculty of Mechatronics, Institute of Metrology and Biomedical Engineering, Boboli 8 St, 02-525 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,8,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/0304-8853(81)90078-0","article-title":"Biomagnetism","volume":"22","author":"Williamson","year":"1981","journal-title":"J. Mag. Mag. Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1016\/0002-8703(63)90075-9","article-title":"Detection of the magnetic field of the heart","volume":"66","author":"Baule","year":"1963","journal-title":"Am. Heart J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"784","DOI":"10.1126\/science.161.3843.784","article-title":"Magnetoencephalography: Evidence of magnetic fields produced by alpha-rhythm currents","volume":"161","author":"Cohen","year":"1968","journal-title":"Science"},{"key":"ref_4","first-page":"246","article-title":"Estimation of hepatic iron stores by in vivo measurement of magnetic susceptibility","volume":"70","author":"Bauman","year":"1967","journal-title":"J. Lab. Clin. Med."},{"key":"ref_5","unstructured":"Andr\u00e4, W., and Nowak, H. (2007). Cardiomagnetism. Magnetism in Medicine: A Handbook, Wiley-VCH Verlag GmbH & Co. KGaA. [2nd ed.]."},{"key":"ref_6","unstructured":"Andr\u00e4, W., and Nowak, H. (2007). Neuromagnetism. Magnetism in Medicine: A Handbook, Wiley-VCH Verlag GmbH & Co. KGaA. [2nd ed.]."},{"key":"ref_7","unstructured":"Andr\u00e4, W., and Nowak, H. (2007). Liver Iron Susceptometry. Magnetism in Medicine: A Handbook, Wiley-VCH Verlag GmbH & Co. KGaA. [2nd ed.]."},{"key":"ref_8","unstructured":"Atsumi, K. (1988). Magnetic activity of a single peripheral nerve in man. Biomagnetism\u201987, Tokyo Denki University Press."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1183\/09031936.93.02020149","article-title":"Magnetopneumography: A general review","volume":"2","author":"Lemaigre","year":"1989","journal-title":"Eur. Respir. J."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1853","DOI":"10.1007\/BF02459126","article-title":"A biomagnetic method for studying gastro-intestinal activity","volume":"11","author":"Comani","year":"1989","journal-title":"Il Nuovo Cimento D"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2293","DOI":"10.1007\/BF02100117","article-title":"Magnetoenterography (MENG): Noninvasive measurement of bioelectric activity in human small intestine","volume":"41","author":"Richards","year":"1996","journal-title":"Dig. Dis. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1088\/0953-2048\/19\/3\/024","article-title":"Biomagnetism using SQUIDs: Status and perspectives","volume":"19","author":"Sternickel","year":"2006","journal-title":"Supercond. Sci. Technol."},{"key":"ref_13","first-page":"216","article-title":"The fetal magnetocardiogram","volume":"2","author":"Kariniemi","year":"1974","journal-title":"J. Perinat. Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1224","DOI":"10.1111\/j.1471-0528.1985.tb04866.x","article-title":"First magnetoencephalographic recording of the brain activity of the human fetus","volume":"92","author":"Blum","year":"1985","journal-title":"Br. J. Obs. Gynaecol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1073","DOI":"10.1016\/j.hrthm.2008.02.035","article-title":"Magnetocardiography for Fetal Arrhythmias","volume":"5","author":"Strasburger","year":"2008","journal-title":"Heart Rhythm"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"K\u00f6rber, R., Kieler, O., H\u00f6mmen, P., H\u00f6fner, N., and Storm, J. (2019, January 28). Ultra-sensitive SQUID systems for applications in biomagnetism and ultra-low field MRI. Proceedings of the 2019 IEEE International Superconductive Electronics Conference, Riverside, CA, USA.","DOI":"10.1109\/ISEC46533.2019.8990912"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1063\/1.1653195","article-title":"Magnetocardiograms taken inside a shielded room with a superconducting point-contact magnetometer","volume":"16","author":"Cohen","year":"1970","journal-title":"Appl. Phys. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"664","DOI":"10.1126\/science.175.4022.664","article-title":"Magnetoencephalography: Detection of the brain\u2019s electrical activity with a superconducting magnetometer","volume":"175","author":"Cohen","year":"1972","journal-title":"Science"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1038\/nphys566","article-title":"Optical magnetometry","volume":"3","author":"Budker","year":"2007","journal-title":"Nat. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"904","DOI":"10.1364\/OE.11.000904","article-title":"Dynamical mapping of the human cardiomagnetic field with a room-temperature, laser-optical sensor","volume":"11","author":"Bison","year":"2003","journal-title":"Opt. Express"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"211104","DOI":"10.1063\/1.2392722","article-title":"Magnetoencephalography with an atomic magnetometer","volume":"89","author":"Xia","year":"2006","journal-title":"Appl. Phys. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"151110","DOI":"10.1063\/1.3491215","article-title":"Ultrahigh sensitivity magnetic field and magnetization measurements with an atomic magnetometer","volume":"97","author":"Dang","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"243703","DOI":"10.1063\/1.3522648","article-title":"Magnetoencephalography with a two-color pump-probe, fiber-coupled atomic magnetometer","volume":"97","author":"Johnson","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"241105","DOI":"10.1063\/1.4770361","article-title":"A low-power, high-sensitivity micromachined optical magnetometer","volume":"101","author":"Mhaskar","year":"2012","journal-title":"Appl. Phys. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1038\/nature01484","article-title":"A subfemtotesla multichannel atomic magnetometer","volume":"422","author":"Kominis","year":"2003","journal-title":"Nature"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"981","DOI":"10.1364\/BOE.3.000981","article-title":"Magnetoencephalography with a chip-scale atomic magnetometer","volume":"3","author":"Sander","year":"2012","journal-title":"Biomed. Opt. Express"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"542","DOI":"10.1016\/j.neuroimage.2016.12.048","article-title":"Measuring MEG closer to the brain: Performance of on-scalp sensor arrays","volume":"147","author":"Iivanainena","year":"2017","journal-title":"Neuroimage"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"133703","DOI":"10.1063\/1.3491548","article-title":"Cross-validation of microfabricated atomic magnetometers with superconducting quantum interference devices for biomagnetic applications","volume":"97","author":"Knappe","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"8153","DOI":"10.1088\/0031-9155\/58\/22\/8153","article-title":"A compact, high performance atomic magnetometer for biomedical applications","volume":"58","author":"Shah","year":"2013","journal-title":"Phys. Med. Biol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"404","DOI":"10.1016\/j.neuroimage.2017.01.034","article-title":"A new generation of magnetoencephalography: Room temperature measurements using optically-pumped magnetometers","volume":"149","author":"Boto","year":"2017","journal-title":"NeuroImage"},{"key":"ref_31","first-page":"240","article-title":"Individualized magnetoencephalography using optically pumped magnetometers with an anatomy derived sensor holder","volume":"63","author":"Yang","year":"2018","journal-title":"Biomed. Eng. Biomed. Tech."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2226","DOI":"10.1109\/TNSRE.2018.2871947","article-title":"Optically Pumped Magnetometers for Magneto-Myography to Study the Innervation of the Hand","volume":"26","author":"Broser","year":"2018","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"e013436","DOI":"10.1161\/JAHA.119.013436","article-title":"Low-Cost Fetal Magnetocardiography: A Comparison of Superconducting Quantum Interference Device and Optically Pumped Magnetometers","volume":"8","author":"Strand","year":"2019","journal-title":"J. Am. Heart Assoc."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Sander, T., Jodko-W\u0142adzi\u0144ska, A., Hartwig, S., Br\u00fchl, R., and Middelmann, T. (2020). Optically pumped magnetometers enable a new level of biomagnetic measurements. Adv. Opt. Technol., under review.","DOI":"10.1515\/aot-2020-0027"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1038\/nature26147","article-title":"Moving magnetoencephalography towards real-world applications with a wearable system","volume":"555","author":"Boto","year":"2018","journal-title":"Nature"},{"key":"ref_36","first-page":"1","article-title":"Fully integrated, standalone zero field optically pumped magnetometer for biomagnetism","volume":"10548","author":"Osborne","year":"2018","journal-title":"Proc. Spie Steep Dispers. Eng. Opto-At. Precis. Metrol. Xi"},{"key":"ref_37","unstructured":"(2020, July 22). Twinleaf microSERF. Available online: https:\/\/twinleaf.com\/vector\/microSERF\/."},{"key":"ref_38","unstructured":"Iwata, G.Z., Hu, Y., Sander, T., Muthuraman, M., Chirumamilla, V.C., Groppa, S., Budker, D., and Wickenbrock, A. (2020, June 20). Biomagnetic Signals Recorded during Transcranial Magnetic Stimulation (TMS)-Evoked Peripheral Muscular Activity. Available online: https:\/\/arxiv.org\/abs\/1909.11451."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"239","DOI":"10.2478\/mms-2013-0021","article-title":"Measures to reduce the residual field and field gradient inside a magnetically shielded room by a factor of more than 10","volume":"20","author":"Voigt","year":"2013","journal-title":"Metrol. Meas. Syst."},{"key":"ref_40","unstructured":"(2020, June 15). QuSpin Zero Field Magnetometer. Available online: http:\/\/quspin.com\/products-qzfm\/."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"879","DOI":"10.1063\/1.1137480","article-title":"Uniform magnetic field produced by three, four, and five square coils","volume":"54","author":"Merritt","year":"1983","journal-title":"Rev. Sci. Instrum."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"135","DOI":"10.4316\/aece.2010.04022","article-title":"Dynamic shielding of the magnetic fields","volume":"10","author":"Baltag","year":"2010","journal-title":"Adv. Electr. Comput. Eng."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"244","DOI":"10.1016\/j.neuroimage.2019.03.022","article-title":"On-scalp MEG system utilizing an actively shielded array of optically-pumped magnetometers","volume":"194","author":"Iivanainen","year":"2019","journal-title":"Neuroimage"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-019-50697-w","article-title":"Balanced, bi-planar magnetic field and field gradient coils for field compensation in wearable magnetoencephalography","volume":"9","author":"Holmes","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_45","unstructured":"(2020, July 21). Bartington Helmholtz Coils. Available online: https:\/\/www.bartington.com\/bartington-helmholtz-coils\/."},{"key":"ref_46","unstructured":"(2020, July 21). Meda: Three Axis Helmholtz Coil Systems. Available online: http:\/\/www.meda.com\/index.php\/products?name=Three-Axis-Helmholtz."},{"key":"ref_47","unstructured":"Serviciencia, S.L.U. (2020, July 21). 1D, 2D and 3D Helmholtz Coils. Available online: http:\/\/www.serviciencia.es\/Helm-i-1.htm."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"6065","DOI":"10.1088\/0031-9155\/58\/17\/6065","article-title":"Multi-sensor magnetoencephalography with atomic magnetometers","volume":"58","author":"Johnson","year":"2013","journal-title":"Phys. Med. Biol."},{"key":"ref_49","unstructured":"(2020, June 15). Vacuumschmelze Magnetically Shielded Room. Available online: https:\/\/www.vacuumschmelze.com\/Products\/Further-Technologies\/Magnetically-Shielded-Rooms-made-of-VACOSHIELD."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1372","DOI":"10.1063\/1.1683678","article-title":"Optimum Spacing of Square and Circular Coil Pairs","volume":"39","author":"Rudd","year":"1968","journal-title":"Rev. Sci. Instrum."},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Restrepo-Alvarez, A.F., Franco-Mejia, E., and Pinedo-Jaramillo, C.R. (2012, January 7\u20139). Study and Analysis of Magnetic Field Homogeneity of Square and Circular Helmholtz Coil Pairs: A Taylor Series Approximation. Proceedings of the VI Andean Region International Conference Andescon 2012, Cuenca, Ecuador.","DOI":"10.1109\/Andescon.2012.27"},{"key":"ref_52","unstructured":"(2016, May 02). FreeCAD. Available online: https:\/\/www.freecadweb.org\/."},{"key":"ref_53","unstructured":"(2020, August 10). Autodesk Inventor. Available online: https:\/\/www.autodesk.com\/products\/inventor."},{"key":"ref_54","unstructured":"(2020, June 15). Stefan Mayer Instruments Fluxgate Magnetometer Fluxmaster. Available online: https:\/\/www.stefan-mayer.com\/en\/products\/magnetometers-and-sensors\/fluxmaster.html."},{"key":"ref_55","unstructured":"(2020, August 10). Fluke 8845A 6.5 Digit Precision Multimeter. Available online: https:\/\/www.fluke.com\/en-us\/product\/precision-measurement\/bench-instruments\/fluke-8845a-8846a."},{"key":"ref_56","unstructured":"(2020, June 15). National Instruments USB-6218 Multifunction I\/O Device. Available online: https:\/\/www.ni.com\/en-gb\/support\/model.usb-6218.html."},{"key":"ref_57","unstructured":"(2020, June 15). Matlab. Available online: http:\/\/www.mathworks.com."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/16\/4563\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:00:56Z","timestamp":1760176856000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/16\/4563"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,8,14]]},"references-count":57,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2020,8]]}},"alternative-id":["s20164563"],"URL":"https:\/\/doi.org\/10.3390\/s20164563","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,8,14]]}}}