The scanning TMR microscope for biosensor applications

Kunal N. Vyas, David M. Love, Adrian Ionescu, Justin Llandro, Pratap Kollu, Thanos Mitrelias, Stuart Holmes, Crispin H.W. Barnes

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


We present a novel tunnel magnetoresistance (TMR) scanning microscope set-up capable of quantitatively imaging the magnetic stray field patterns of micron-sized elements in 3D. By incorporating an Anderson loop measurement circuit for impedance matching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3D rastering a mounted TMR sensor over our magnetic barcodes, we are able to characterise the complex domain structures by displaying the real component, the amplitude and the phase of the sensor's impedance. The modular design, incorporating a TMR sensor with an optical microscope, renders this set-up a versatile platform for studying and imaging immobilised magnetic carriers and barcodes currently employed in biosensor platforms, magnetotactic bacteria and other complex magnetic domain structures of micron-sized entities. The quantitative nature of the instrument and its ability to produce vector maps of magnetic stray fields has the potential to provide significant advantages over other commonly used scanning magnetometry techniques.

Original languageEnglish
Pages (from-to)172-186
Number of pages15
Issue number2
Publication statusPublished - 2015
Externally publishedYes


  • 3D magnetic stray field mapping
  • Domain wall characterisation
  • Magnetic carriers
  • TMR-scanning microscope

ASJC Scopus subject areas

  • Clinical Biochemistry


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