{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T17:15:10Z","timestamp":1774458910987,"version":"3.50.1"},"reference-count":7,"publisher":"AIP Publishing","issue":"10","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2002,5,15]]},"abstract":"<jats:p>Superparamagnetic labels, 400 nm dextran iron oxide particles and 2 \u03bcm polymer encapsulated iron oxide microspheres, with biomolecules immobilized on the surface, e.g., the enzyme horseradish peroxidase (20\u201340 molecules per label) were controllably placed on chip sites (5\u00d715\u2009\u03bcm2) using tapered Al current lines (10\u201320 mA current) and moved to and from adjacent spin valve sensors [2\u00d76\u2009\u03bcm,2, magnetoresistance (MR) \u223c5%]. Average MR signals of 1.2 and 0.6 mV were obtained for the detection of bulk numbers of 400 nm and 2 \u03bcm labels respectively using an on-chip field of 15 Oe and a sense current of 5 mA. The moment per label was calculated at 5\u00d710\u221213\u2009emu for the 400 nm labels and 5\u00d710\u221212\u2009emu for the 2 \u03bcm labels, illustrating the higher density of the 400 nm particles. MR signals of \u223c100 \u03bcV were obtained for single 2 \u03bcm labels positioned over the spin valve sensor using an on-chip field of 15 Oe and 8 mA sense current. The corresponding sensor saturation occurred at \u223c1 mV, with a noise level of \u223c10 \u03bcV. The estimated maximum MR signal for one 2 \u03bcm label directly on top of the sensor was \u223c400 \u03bcV. Biotechnological applications include high sensitivity biosensors and biochips for protein and DNA screening.<\/jats:p>","DOI":"10.1063\/1.1451898","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:24:57Z","timestamp":1027693497000},"page":"7786-7788","update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":157,"title":["Single magnetic microsphere placement and detection on-chip using current line designs with integrated spin valve sensors: Biotechnological applications"],"prefix":"10.1063","volume":"91","author":[{"given":"D. L.","family":"Graham","sequence":"first","affiliation":[{"name":"Instituto de Engenharia de Sistemas e Computadores (INESC)"},{"name":"Centre for Biological and Chemical Engineering, (IST), Lisbon\u20091000-029, Portugal"}]},{"given":"H.","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Instituto de Engenharia de Sistemas e Computadores (INESC)"},{"name":"Physics Department, Instituto Superior T\u00e9cnico (IST), Lisbon\u20091000-029, Portugal"}]},{"given":"J.","family":"Bernardo","sequence":"additional","affiliation":[{"name":"Instituto de Engenharia de Sistemas e Computadores (INESC), Lisbon\u20091000-029, Portugal"}]},{"given":"P. P.","family":"Freitas","sequence":"additional","affiliation":[{"name":"Instituto de Engenharia de Sistemas e Computadores (INESC)"},{"name":"Physics Department, Instituto Superior T\u00e9cnico (IST), Lisbon\u20091000-029, Portugal"}]},{"given":"J. M. S.","family":"Cabral","sequence":"additional","affiliation":[{"name":"Centre for Biological and Chemical Engineering, (IST), Lisbon\u20091000-029, Portugal"}]}],"member":"317","reference":[{"key":"2024020608552515600_r1","doi-asserted-by":"crossref","first-page":"2442","DOI":"10.1103\/PhysRevLett.57.2442","volume":"57","year":"1986","journal-title":"Phys. Rev. Lett."},{"key":"2024020608552515600_r2","doi-asserted-by":"crossref","first-page":"2472","DOI":"10.1103\/PhysRevLett.61.2472","volume":"61","year":"1988","journal-title":"Phys. Rev. Lett."},{"key":"2024020608552515600_r3","doi-asserted-by":"crossref","first-page":"731","DOI":"10.1016\/S0956-5663(98)00037-2","volume":"13","year":"1998","journal-title":"Biosens. Bioelectron."},{"key":"2024020608552515600_r4"},{"key":"2024020608552515600_r5","first-page":"129","volume":"28","year":"1994","journal-title":"Essays Biochem."},{"key":"2024020608552515600_r6","doi-asserted-by":"crossref","first-page":"6469","DOI":"10.1021\/ja983984p","volume":"121","year":"1999","journal-title":"J. Am. Chem. Soc."},{"key":"2024020608552515600_r7","doi-asserted-by":"crossref","first-page":"3678","DOI":"10.1021\/ac000129r","volume":"72","year":"2000","journal-title":"Anal. Chem."}],"container-title":["Journal of Applied Physics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.aip.org\/aip\/jap\/article-pdf\/91\/10\/7786\/19196462\/7786_1_online.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.aip.org\/aip\/jap\/article-pdf\/91\/10\/7786\/19196462\/7786_1_online.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,2,6]],"date-time":"2024-02-06T09:12:28Z","timestamp":1707210748000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.aip.org\/jap\/article\/91\/10\/7786\/485878\/Single-magnetic-microsphere-placement-and"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2002,5,15]]},"references-count":7,"journal-issue":{"issue":"10","published-print":{"date-parts":[[2002,5,15]]}},"URL":"https:\/\/doi.org\/10.1063\/1.1451898","relation":{},"ISSN":["0021-8979","1089-7550"],"issn-type":[{"value":"0021-8979","type":"print"},{"value":"1089-7550","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2002,5,15]]},"published":{"date-parts":[[2002,5,15]]}}}