Ingenieurwissenschaften und zugeordnete Tätigkeiten
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The implementation of fluorescent methods is of outstanding importance in the field of optical chemical sensor Technology and biosciences. Their bioanalytical applications are manifold including fluorescence microscopy, fluorescence in situ hybridization, DNA sequencing, fluorescence-activated cell sorting, immunoassays, analysis of DNA and Protein microarrays, and quantitative PCR, just to name a few examples. Particularly, fluorescence microscopy is a valuable method in the versatile field of biomedical imaging methods which nowadays utilizes different fluorescence Parameters like emission wavelength/Color and lifetime for the discrimination between different targets. Sectional Images are available with confocal microscopes. Tissue, cells or single cellular compartments can be stained and visualized with fluorescent dyes and biomolecules can be selectively labeled with fluorescent dyes to Monitor biomolecular interactions inside cells or at Membrane bound receptors.
On the other hand , fluorophores can act as indicator (or "molecular probe") to visualize intrinsically colorless and non-fluorescent ionic and neutral analytes such as pH, Oxygen (pO2), metal ions, anions, hydrogen peroxide or bioactive small organic molecules such as Sugars or nucleotides. Thereby, their photoluminescent properties (fluorescence or phoporescence intensity, exitation and/or Emission wavelength, emission lifetime or anisotropy) respond to the presence of these species in their immediate Environment. In general, the use of luminescent probes has the advantage that they can be delivered directly into the sample, and detected in a contactless remote mode. By now, these probes are often encapsulated in different types of nanoparticles (NPs) made from (biodegradable) organic polymers, biopolymers or inorganic materials like silica or bound to their surface.
The unparalleled excited-state potential-energy landscape of the chromium(III)-based dye [1]3+ ([Cr(ddpd)2]3+; ddpd=N,N’-dimethyl-N,N’-dipyridin-2-ylpyridin-2,6-diamine) enables a strong dual emission in the near infrared region. The temperature dependence of this dual emission allows the use of [1]3+ as an unprecedented molecular ratiometric thermometer in the 210–373 K temperature range in organic and in aqueous media. Incorporation of [1]3+ in biocompatible nanocarriers, such as 100 nm-sized polystyrene nanoparticles and solutol micelles, provides nanodimensional thermometers operating under physiological conditions.
A set of highly fluorescent, pH-responsive boron dipyrromethene dyes covering the pH range of 5-12 is presented for broad range pH measurements in mixed aqueous-organic median and polymer matrices. Readout in the intensity Domain with low cost and miniaturized Instrumentation utilizes reversible protonation induced switching ON of their initially completely quenched flourescence mediated by photoinduced electron Transfer. All dyes, rationally designed to reveal closely matching Absorption and Emission properties, are accessible via facile two-step reactions in Overall yields of up to 20%. By modifying the Substitution pattern of the meso-Aryl substiuent, the pKa values could be fine-tuned from 6 to 11. Integration of these molecules into polymeric films by a simple mixing procedure yielded reversible and longterm stable pH sensors for naked eye detection.
Structural health monitoring contributes to early damage detection in the built infrastructure. During the last two decades, sensor networks transferred from wired to wireless sensor networks. Several methods exist to measure moisture in building materials. Most of the introduced commercial moisture measurement methods provide information about the local or near surface moisture. A feasibility study is presented to demonstrate, how the Received Signal Strength Indicator (RSSI) of a Bluetooth Low Energy (BLE) signal, transmitted from the BLE-module embedded in building materials, correlate with changing moisture content. The feasibility of this influence was investigated in the presented study. The maximum and minimum RSSI were systematically recorded and analysed.
Due to the promising combination of chemical, thermal and mechanical properties, springs made of advanced ceramics have attracted much attention as a replacement for metal springs in highly demanding applications, operating at high temperatures and in harsh environments when hardened metals can no longer be used. A further application was recently proposed by using ceramic springs with metalized surfaces as capacitive force sensors. Prior to any design of an instrument, application-specific static and/or dynamic loading experiments are necessary to investigate the stability of spring properties under the given conditions. These experiments can also be used to determine seldom measured material properties like the shear modulus of ceramics.
Helical Springs with a rectangular cross-section have been machined from straight tubes of alumina (99.99% α-AI203,) and zirconia (Y/Ce-TZP). The sintered density of both materials was above 99% of the theoretical density.
The stress/displacement curves turned out to be extremely linear and the spring constants were not altered, even after more than one million cycles of compression loading at various temperatures from -15°C to +60°C. This means that such springs can be a far more reproducible and reliable source of an elastic response to applied forces than handmade springs from molten quartz wires. The behavior found for in-house fabricated springs contrasts to the behavior found for a commercial ceramic spring, which was produced by injection molding and exhibits a less linear response.
Furthermore, high-temperature displacement behavior of fabricated alumina and zirconia springs was tested under static loading conditions in different atmospheres (air, N2 and H2) at temperatures up to 1000 °C.