The Group

Particles are everywhere

In the air we inhale, to the bread, salt and pepper on the dinner table, in our dental fillings, in every pill we take, in the tires we drive on, the cement we build our houses with, the paint on the walls and so on… What is really new with particles, however, is the superior understanding we rapidly develop at the nanoscale, the new size limit in applied sciences and, in particular, in life sciences and medicine. This can only be compared to the excitement with the micro-scale in the mid-19^th century. So with state-of-the art computational tools and diagnostics this understanding facilitates a much better connection between material performance and particle characteristics creating new excitement with particles.

Today an array of nanomaterials can be readily produced at kg/h with closely controlled size, composition and morphology, even at university laboratories. This facilitates the creation of spinoffs for niche markets like nanofluids, smart clothing and biomaterials to name a few. The dynamics of the mesmerizing and omnipresent fractal-like structures of nanoparticles (when made in mass) are better understood to systematically design and operate their manufacturing units. For example, novel computational schemes reveal that power laws govern the evolution from physically-bonded soft agglomerates of nanoparticles to chemically- or sinter-bonded hard-agglomerates or aggregates regardless of material composition and polydispersity. Understanding is rapidly advancing also at the sub-particle level, molecular or atomistic, with clever algorithms and hardware. This facilitates the development of process design correlations from first principles rigorously tested with data. New techniques such as tandem mass-mobility measurements not only quantify the above agglomerate structures but give the size of constituent nanoparticles when interfaced with the above power laws. That way the nanoparticle size, a key performance characteristic, is given online rather than from tedious offline microscopic or adsorption measurements that in many ways hinder efficient manufacturing.

This understanding now facilitates the creation of sophisticated devices containing nanoparticles with closely controlled characteristics such as gas sensors and heterogeneous catalysts containing multicomponent noble metal alloys that were not available with conventional technologies. For example, industrial prototypes of gas sensors that can selectively detect breath acetone, a tracer for diabetes or fat burning, are developed. That way clinical tests can be planned that can phase out the painful finger pricking for glucose testing of diabetics. In a lighter application, such sensors could show when a gym workout is burning undesirable body fat. Frankly there are great opportunities for particle technology in life sciences that can be materialized by close interaction particle scientists with the medical doctors as we have seen with the impact of particle technology in pharmacy in recent years.

These nanoparticle successes, promises and potential, however, should not let us overlook the need of better understanding the health impact of nanomaterials. Today the public is far more cautious with such scientific discoveries asking for proof that they are human-friendly. For example, just a few years ago the U.S. EPA had been petitioned to label nanosilver (silver nanoparticles) as pesticide, the kiss to death of any consumer product, for its impact on aquatic life. Science, however, clearly differentiated the role of silver ions and particles and today nanosilver is the largest engineered nanomaterial in the market after the classics, carbon black and fumed oxides.

To close, though still a lot needs to be learned with particles, enough is known to make an impact on the needs of the society for sustainable living, energy and quality of life to name a few that readily come to mind. Frankly it seems that we live at a great time for particle technology and innovation.

German Article

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