Di Michele, L; Shelly, C; de Marco, P; See, P; Cox, D; Kazakova, O (2011) Detection and susceptibility measurements of a single Dynal bead. J. Appl. Phys., 110 (6). 063916

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Abstract

In this work we present detection and susceptibility measurements experiments on a single superparamagnetic Dynal bead with diameter of 1 um and magnetic moment of ~4 × 10^8 uB. The accurate bead positioning has been achieved by non-invasive AFM nanomanipulation. The detection and magnetic characterization of the bead was performed using ultra-sensitive InSb Hall devices. Single bead detection was demonstrated using a step - wise change of DC magnetic field, measurements were performed using only in-phase component of the total AC Hall voltage. A very clear evidence of the bead presence has been demonstrated simultaneously with explicit separation of parasitic inductive signals. Additional experiments performed using a sweeping change of DC field allowed susceptibility measurements of a single Dynal bead. Numerical outcomes of both sweeping and stepping experiments are in a very good agreement. The method presented here opens up new possibilities for reliable and accurate detection of small magnetic moments, which is of high importance for metrological applications as well as highly sensitive biological, medical and environmental detectors.

Item Type:	Article
Keywords:	Hall sensor, superparamegnetic nanoparticle, single particle detection, nanosensor
Subjects:	Quantum Phenomena Quantum Phenomena > Nanophysics
Identification number/DOI:	10.1063/1.3638124
Last Modified:	02 Feb 2018 13:14
URI:	https://eprintspublications.npl.co.uk/id/eprint/5295