May 2nd, 2012
Magnetic nanoparticles are known to have very interesting properties both in zero-field and in an applied magnetic field. Interestingly, they form these unique structures known as chains when subject to a strong-enough magnetic field. This effect can be detrimental to several applications of magnetic nanoparticles including their use in MRI as contrast agents as carriers for drug delivery. Chaining, its effects on applications and its prevention are aspects that I’m exploring in my PhD.
Pictured below are 2 long chains of magnetic nanoparticles that appear to be in the process of forming a large 12 micron super-chain. The individual chains themselves appear to be composed of smaller units, suggesting how chains evolve over time.
Magnetic nanoparticles chaining in an applied magnetic field
November 29th, 2011
Want a brand new wallpaper of magnetic nanoparticles? Look here.
The image is based on a TEM image I took this year of self-assembled magnetic nanoparticles.
Magnetite nanoparticles self-assembling in a drying droplet - 1920 x 1080
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1280 x 800
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November 28th, 2011
Combining two differently sized magnetic nanoparticles can lead to interesting self-assembly effects. This follows on neatly from my previous self-assembly post. So how do 7 nm particles combined with 15 nm particles self-assemble?
The high surface-tension of evaporating water droplets push the particles together, forcing them to assemble in a space-efficient array. Interestingly, the particles appear to self-assemble based on size, where 7 nm particles and 15 nm particles separate so that they can pack together more efficiently. If the size ratio changes, different effects could be seen such as small particles fitting in between spaces left by larger particles. Some neat images:
7 nm and 15 nm diameter magnetic nanoparticles self-assembling