Devices for measuring superfine particle masses are used for detecting and/or analyzing emissions from aerosols or dust in general. Of particular interest in the first instance are the purely physical deposition kinetics on certain surfaces (deposition surfaces) resulting from adsorption. In this context, the superfine particle masses can also diffuse into the surface, i.e., be taken up and intercalated in the course of a physical diffusion process (absorption). Chemical and physical interactions of the superfine particles on or in the deposition surfaces can be detected using these devices and quantified through application of additional morphological, physical or chemical analysis methods of the known type.
Another field of application of the aforementioned devices is the in vitro analyses of superfine dust deposits or biochemical or biophysical interactions on bioassays, i.e., on biological or biologically active surfaces. Analyses of this kind constitute a useful and, due to ethical considerations, preferable way to supplement epidemiological investigations (using statistical data) or in vivo analyses on living beings (for example, tests on animals), such as to make toxicological assessments of atmospheric dust and pollutant loads, for example, at contaminated workplaces, in traffic or in industrial installations.
Importance is accorded to emissions analysis in the context of what is generally referred to as superfine particle loads. Superfine particles, also known as nanoparticles, refer to particles having diameters in the submicrometer region, i.e., of a few nanometers up to maximally one micrometer. Due to their very large surface area-to-mass ratio in comparison to larger particles or solids, superfine particles exhibit an often completely different and often not yet fully investigated and thus unknown property profile and reaction behavior.
In recent years, epidemiological and toxicological investigations have revealed, for example, that increased emissions of such superfine particles are accompanied by a significant increase in the occurrence of various diseases, such as heart/circulatory disturbances or chronic respiratory difficulties. To provide a comprehensive emissions protection for the population, new boundary limits were derived therefrom. However, under the present technical and economic boundary conditions, these would require drastic measures and are not observable.
However, a device of the aforementioned type permits the analyses of superfine particle loading that is more goal-oriented, whereby the mentioned measures are also able to be introduced in a more targeted and thus efficient manner. Therefore, there is no longer a need for comprehensive measures that are difficult to implement.
In vitro investigations for measuring superfine particle masses, as well as their toxicological effects on living organisms, often utilize biological model structures, such as cell cultures, for example, on a suitable cultivation support structure, such as a Petri dish or, in the case of bacterial cultures, a nutrient medium. The structures are exposed as an open layer to the aerosol or to a suspension of a carrier fluid (gas or liquid) and the superfine particles.
DE 198 01 763 C2 describes a culture device for cultivating cells or tissue components where the cell cultures are grown on porous membranes in Transwell inserts. For the aforementioned in vitro investigations, the nutrient solution on the top side of the planar cultures is removed to permit application of an aerosol, while the space underneath the membrane is continuously rinsed with fresh nutrient medium for purposes of supplying the cells and avoiding an accumulation of toxic metabolic products. The system has already established itself under the CULTEX® brand name in many areas of inhalation research, such as in the investigations of Diesel soot and cigarette smoke.
However, the in vitro investigations known till now are based exclusively on time-integral measurements. In the same way as the mentioned in vivo investigations, the cell cultures are investigated at intervals, i.e., only after a specific test duration has elapsed. Fluctuations in an aerosol emission and the temporary biochemical effects thereof on a cell culture can often not be understood or can only be very imprecisely understood, for example, on the basis of individual tests.