{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T15:58:41Z","timestamp":1778774321668,"version":"3.51.4"},"reference-count":40,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2017,6,6]],"date-time":"2017-06-06T00:00:00Z","timestamp":1496707200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004917","name":"Cancer Prevention Research Institute of Texas","doi-asserted-by":"publisher","award":["RP150343"],"award-info":[{"award-number":["RP150343"]}],"id":[{"id":"10.13039\/100004917","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000001","name":"the National Science Foundation","doi-asserted-by":"publisher","award":["CBET-0932971"],"award-info":[{"award-number":["CBET-0932971"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"the National Institutes of Health","doi-asserted-by":"publisher","award":["1RC1RR028465"],"award-info":[{"award-number":["1RC1RR028465"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Ta\/Ru\/Co\/Ru\/Co\/Cu\/Co\/Ni80Fe20\/Ta spin-valve giant magnetoresistive (GMR) multilayers were deposited using UHV magnetron sputtering and optimized to achieve a 13% GMR ratio before patterning. The GMR multilayer was patterned into 12 sensor arrays using a combination of e-beam and optical lithographies. Arrays were constructed with 400 nm \u00d7 400 nm and 400 nm \u00d7 200 nm sensors for the detection of reporter nanoparticles. Nanoparticle detection was based on measuring the shift in high-to-low resistance switching field of the GMR sensors in the presence of magnetic particle(s). Due to shape anisotropy and the corresponding demag field, the resistance state switching fields were significantly larger and the switching field distribution significantly broader in the 400 nm \u00d7 200 nm sensors as compared to the 400 nm \u00d7 400 nm sensors. Thus, sensor arrays with 400 nm \u00d7 400 nm dimensions were used for the demonstration of particle detection. Detection of a single 225 nm Fe3O4 magnetic nanoparticle and a small number (~10) of 100 nm nanoparticles was demonstrated. With appropriate functionalization for biomolecular recognition, submicron GMR sensor arrays can serve as the basis of ultrasensitive chemical and biological sensors.<\/jats:p>","DOI":"10.3390\/s17061296","type":"journal-article","created":{"date-parts":[[2017,6,6]],"date-time":"2017-06-06T10:53:09Z","timestamp":1496746389000},"page":"1296","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Ultrasensitive Magnetic Nanoparticle Detector for Biosensor Applications"],"prefix":"10.3390","volume":"17","author":[{"given":"Yu-Chi","family":"Liang","sequence":"first","affiliation":[{"name":"Department of Chemical &amp; Biomolecular Engineering, University of Houston, Houston, TX 77204, USA"},{"name":"Center for Integrated Bio &amp; Nano Systems, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Long","family":"Chang","sequence":"additional","affiliation":[{"name":"Center for Integrated Bio &amp; Nano Systems, University of Houston, Houston, TX 77204, USA"},{"name":"Department of Electrical &amp; Computer Engineering, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenlan","family":"Qiu","sequence":"additional","affiliation":[{"name":"Center for Integrated Bio &amp; Nano Systems, University of Houston, Houston, TX 77204, USA"},{"name":"Materials Science &amp; Engineering, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arati","family":"Kolhatkar","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Binh","family":"Vu","sequence":"additional","affiliation":[{"name":"Department of Chemical &amp; Biomolecular Engineering, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Katerina","family":"Kourentzi","sequence":"additional","affiliation":[{"name":"Department of Chemical &amp; Biomolecular Engineering, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9584-8861","authenticated-orcid":false,"given":"T.","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Youli","family":"Zu","sequence":"additional","affiliation":[{"name":"Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX 77030, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richard","family":"Willson","sequence":"additional","affiliation":[{"name":"Department of Chemical &amp; Biomolecular Engineering, University of Houston, Houston, TX 77204, USA"},{"name":"Centro de Biotecnolog\u00eda FEMSA, Departamento de Biotecnolog\u00eda e Ingenier\u00eda de Alimentos, Tecnol\u00f3gico de Monterrey, Monterrey, NL 64849, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2272-562X","authenticated-orcid":false,"given":"Dmitri","family":"Litvinov","sequence":"additional","affiliation":[{"name":"Department of Chemical &amp; Biomolecular Engineering, University of Houston, Houston, TX 77204, USA"},{"name":"Center for Integrated Bio &amp; Nano Systems, University of Houston, Houston, TX 77204, USA"},{"name":"Department of Electrical &amp; Computer Engineering, University of Houston, Houston, TX 77204, USA"},{"name":"Materials Science &amp; Engineering, University of Houston, Houston, TX 77204, USA"},{"name":"Department of Chemistry, University of Houston, Houston, TX 77204, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,6,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2472","DOI":"10.1103\/PhysRevLett.61.2472","article-title":"Giant Magnetoresistance of (001)Fe\/(001) Cr Magnetic Superlattices","volume":"61","author":"Baibich","year":"1988","journal-title":"Phys. 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