Spin-Valve based magnetoresistive nanoparticle detector for applications in biosensing

Wenlan Qiu, Long Chang, Yu Chi Liang, Julia Litvinov, Jing Guo, Yi Ting Chen, Binh Vu, Katerina Kourentzi, Shoujun Xu, T. Randall Lee, Youli Zu, Richard C. Willson, Dmitri Litvinov

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


A magnetoresistive sensor platform for the detection of individual magnetic reporter particles is presented. The sensing scheme is based on the detection of the shift in the sensor's magnetoresistance-switching field in the presence of magnetic particle(s). A bottom-pinned spin-valve multilayer (Co/Ru/Co)/Cu/(Co/Ru/Co) device structure (with Ta/Ru seed and Ta capping layers) used for the sensor was deposited using ultra-high vacuum magnetron sputtering and patterned using conventional microfabrication techniques. Inexpensive electronics to measure device magnetoresistance (using DC currents) was used for testing. The detection of individual 500 nm Fe3O4 nanoparticles as well as the detection of up to ten (10) nanoparticles was demonstrated and verified using scanning electron microscopy (SEM). The developed sensors are readily integratable into a biosensing platform for the detection of biomolecules at ultra-low concentration using magnetic nanoparticles as reporters.

Original languageEnglish (US)
Pages (from-to)174-180
Number of pages7
JournalSensors and Actuators, A: Physical
StatePublished - Oct 1 2017


  • Bioinstrumentation
  • Biosensor
  • Magnetic particle detection
  • Magnetoresistive sensors

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering


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