Sensor platforms can benefit from the incorporation of polymer brushes since brushes can concentrate the analyte near the sensor surface. Brushes that absorb acetone vapor are of particular interest since acetone is an important marker for biological processes. We present a simple procedure to synthesize acetone-responsive poly(methyl acrylate) brushes. Using spectroscopic ellipsometry, we show that these brushes respond within seconds and swell by more than 30% when exposed to acetone vapor. Moreover, quartz crystal microbalance measurements demonstrate that the brushes can be exploited to increase the acetone detection sensitivity of sensors by more than a factor 6. Surprisingly, we find that the swelling ratio of the brushes in acetone vapor is independent of the grafting density and the degree of polymerization of the polymers in the brush. This is qualitatively different from swelling of the same brushes in liquid environments, where the swelling ratio decreases for increasing grafting densities. Yet, it indicates that the brushes are robust and reproducible candidates for implementation in vapor sensor systems.

Heterostructures formed by LaSrMnO/ZnO (LSMO/ZnO) interfaces exhibit extremely interesting electronic properties making them promising candidates for novel oxide p-n junctions, with multifunctional features. In this work, the structure of the interface is studied through a combined experimental/theoretical approach. Heterostructures were grown epitaxially and homogeneously on 4″ silicon wafers, characterized by advanced electron microscopy imaging and spectroscopy and simulated by ab initio density functional theory calculations. The simulation results suggest that the most stable interface configuration is composed of the (001) face of LSMO, with the LaO planes exposed, in contact with the (112̅0) face of ZnO. The ab initio predictions agree well with experimental high-angle annular dark field scanning transmission electron microscopy images and confirm the validity of the suggested structural model. Electron energy loss spectroscopy confirms the atomic sharpness of the interface. From statistical parameter estimation theory, it has been found that the distances between the interfacial planes are displaced from the respective ones of the bulk material. This can be ascribed to the strain induced by the mismatch between the lattices of the two materials employed.

A novel selective epitaxial growth (SEG) technique for (YBCO) thin films is presented. The method involves the deposition of a thin (about 10 nm) metal layer, in the desired pattern, on a substrate before the deposition of the superconducting thin film. During growth the metal reacts with the YBCO, forming locally an insulating compound. Best results are obtained with Ti or W, yielding structures with sharp boundaries and creating insulating areas with high resistivities. The technique has been analysed for the titanium case. It was found that during the YBCO growth the titanium layer reacts with the YBCO to form an amorphous Ba-Ti-O compound. The YBCO cannot grow epitaxially on top of this layer, and a mainly amorphous YBCO film with insulating characteristics results. The resistivity of the insulating parts has been investigated as a function of the layer thicknesses of both the titanium and the YBCO. Both increasing the YBCO layer or a slight decrease of the titanium layer thickness yields a strong decrease in the resistivity. The SEG technique has been successfully applied to create submicron patterns, without any sign of degradation. Bridge structures with widths down to 200 nm could be prepared that still showed a value of 89 K and values in excess of at 77 K.

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Micro Ring Resonators (MRRs) have become the workhorse in photonics, both for data/telecom as well as bio-chemical sensing applications. In this contribution the use of MRRs as sensors for food-safety applications will be discussed.