{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,20]],"date-time":"2026-06-20T17:57:54Z","timestamp":1781978274393,"version":"3.54.5"},"reference-count":36,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2021,4,6]],"date-time":"2021-04-06T00:00:00Z","timestamp":1617667200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006730","name":"Ministry of Education and Research, Romania","doi-asserted-by":"publisher","award":["CCDI-UEFISCDI project number PED 315\/2020"],"award-info":[{"award-number":["CCDI-UEFISCDI project number PED 315\/2020"]}],"id":[{"id":"10.13039\/501100006730","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100006730","name":"Ministry of Education and Research, Romania","doi-asserted-by":"publisher","award":["CCDI-UEFISCDI project number 3PCCDI\/2018 within PNCDI III"],"award-info":[{"award-number":["CCDI-UEFISCDI project number 3PCCDI\/2018 within PNCDI III"]}],"id":[{"id":"10.13039\/501100006730","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Many applications require galvanic isolation between the circuit where the current is flowing and the measurement device. While for AC, the current transformer is the method of choice, in DC and, especially for low currents, other sensing methods must be used. This paper aims to provide a practical method of improving the sensitivity and linearity of a giant magnetoresistance (GMR)-based current sensor by adapting a set of design rules and methods easy to be implemented. Our approach utilizes a multi-trace current trace and a double differential GMR based detection system. This essentially constitutes a planar coil which would effectively increase the usable magnetic field detected by the GMR sensor. An analytical model is developed for calculating the magnetic field generated by the current in the GMR sensing area which showed a significant increase in sensitivity up to 13 times compared with a single biased sensor. The experimental setup can measure both DC and AC currents between 2\u2013300 mA, with a sensitivity between 15.62 to 23.19 mV\/mA, for biasing fields between 4 to 8 Oe with a detection limit of 100 \u03bcA in DC and 100 to 300 \u03bcA in AC from 10 Hz to 50 kHz. Because of the double differential setup, the detection system has a high immunity to external magnetic fields and a temperature drift of the offset of about \u22122.59 \u00d7 10\u22124 A\/\u00b0C. Finally, this setup was adapted for detection of magnetic nanoparticles (MNPs) which can be used to label biomolecules in lab-on-a-chip applications and preliminary results are reported.<\/jats:p>","DOI":"10.3390\/s21072564","type":"journal-article","created":{"date-parts":[[2021,4,6]],"date-time":"2021-04-06T10:34:12Z","timestamp":1617705252000},"page":"2564","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Low Field Optimization of a Non-Contacting High-Sensitivity GMR-Based DC\/AC Current Sensor"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4878-5815","authenticated-orcid":false,"given":"Cristian","family":"Mu\u0219uroi","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering and Applied Physics, Transilvania University of Brasov, Blvd. Eroilor 29, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mihai","family":"Oproiu","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Applied Physics, Transilvania University of Brasov, Blvd. Eroilor 29, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1160-9650","authenticated-orcid":false,"given":"Marius","family":"Volmer","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Applied Physics, Transilvania University of Brasov, Blvd. Eroilor 29, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jenica","family":"Neamtu","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Electrical Engineering, Splaiul Unirii 313, 030138 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marioara","family":"Avram","sequence":"additional","affiliation":[{"name":"National Institute for Research and Development in Microtechnologies, Str. Erou Iancu Nicolae 32B, 72996 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7145-8762","authenticated-orcid":false,"given":"Elena","family":"Helerea","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Applied Physics, Transilvania University of Brasov, Blvd. Eroilor 29, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4108","DOI":"10.1109\/TVT.2009.2022081","article-title":"Current Sensing for Automotive Electronics\u2014A Survey","volume":"58","author":"Patel","year":"2009","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Soliman, E., Hofmann, K., Reeg, H., and Schwickert, M. (2016, January 20\u201322). 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