A code with a twist: Supraparticle microrod composites with direction dependent optical properties as anti-counterfeit labels

Wintzheimer S, Granath T, Eppinger A, Goncalves MR, Mandel K (2019)

Publication Type: Journal article

Publication year: 2019

Journal

Nanoscale Advances Royal Society of Chemistry

Book Volume: 1

Pages Range: 1510-1515

Journal Issue: 4

DOI: 10.1039/c8na00334c

Abstract

Superparamagnetic iron oxide nanoparticles can be assembled to form anisotropic microrod supraparticles with the assistance of a magnetic field during synthesis. Optionally, these iron oxide microrods can furthermore be coated with a thin silica shell. Due to their anisotropic structure, both microrod types can be aligned in a magnetic field while being dispersed in a matrix material which can be cured during the alignment of the microrods. In this way, an anisotropic magnetic composite is obtained. Interestingly, it was observed that the optical extinction properties for visible light in such a composite are direction dependent, which can be explained by using appropriate models based on Maxwell equations. Based on the understanding of this principle, a clever approach for a hidden code could be proposed which is obtained from mixing pure iron oxide and silica coated microrod supraparticles in such an anisotropic composite. The hidden code, which comes down to obtaining a single value eventually, can only be revealed when knowing that the system needs to be measured with a certain "twist".

Authors with CRIS profile

Susanne Wintzheimer Professur für Anorganische Chemie Tim Granath
Karl Mandel

Involved external institutions

Universität Ulm DE Germany (DE) Julius-Maximilians-Universität Würzburg DE Germany (DE) Fraunhofer Institut für Silicatforschung (ISC) DE Germany (DE)

How to cite

APA:

Wintzheimer, S., Granath, T., Eppinger, A., Goncalves, M.R., & Mandel, K. (2019). A code with a twist: Supraparticle microrod composites with direction dependent optical properties as anti-counterfeit labels. Nanoscale Advances, 1(4), 1510-1515. https://dx.doi.org/10.1039/c8na00334c

MLA:

Wintzheimer, Susanne, et al. "A code with a twist: Supraparticle microrod composites with direction dependent optical properties as anti-counterfeit labels." Nanoscale Advances 1.4 (2019): 1510-1515.

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