Werner Zapka

Magnetic behavior of coated superparamagnetic iron oxide nanoparticles in ferrofluids

We present a study on the magnetic behavior of nanosized iron oxide particles coated with different surfactants (sodium oleate, PVA and starch) in a ferrofluid. The effect of the coating material, and different particle concentrations in the ferrofluid have been magnetically investigated to determine the effective magnetic particle size and possible interaction. The superparamagnetic iron oxide particles, synthesized by a controlled co-precipitation technique, are found to contain magnetite (Fe 3 O 4 ) as a main phase with a narrow physical particle size distribution between 6 and 8 nm. The mean effective magnetic size of the particles in different ferrofluid systems are estimated to be around 4-5 nm which is smaller than the physical particle size. On a 10% dilution in the starch coated ferrofluid we observe a decrease in the blocking temperature.

79.4: Light‐Rolls: High Throughput Manufacture for LED Lighting and Displays

A high-throughput, roll-to-roll technology based on three key manufacturing platforms — 3-D MEMS, fluidic chip assembly and ink jet printing, is presented. The target applications for the technology are Displays and Lightings. In particular, flexible, pixilated LED displays can be produced, based on the integration of LED chips onto flexible polymer substrates. The preliminary evaluation of the manufacturing platforms and initial technology validator demonstrators will be presented.

Direct-Write Process for UV-Curable Epoxy Materials by Inkjet Technology

Abstract : We demonstrate drop-on-demand inkjet printing technique to be a high throughput method for the patterned deposition of UV-curable epoxy materials. Different multi-nozzle printheads have been used to produce epoxy droplets with controlled volume in the range from 15 to 180 pl, and to apply the droplets with high placement accuracy. For a large dot grid pattern, which was printed by addressing 126 individual ink channels, standard deviations of sigma(x) = 2.3 micrometer and sigma(y) = 2.6 micrometers have been achieved for the error in dot placement. The deposited epoxy dots were found to form planar convex lenses with a focal length of 142 micrometer. In addition, we have successfully printed magnetic nanoparticles in a carrier fluid with the drop-on-demand printheads, as a step towards the production of composites.