Nanosystems Initiative Munich

About: Nanosystems Initiative Munich is a facility organization based out in Munich, Germany. It is known for research contribution in the topics: Quantum dot & Perovskite (structure). The organization has 323 authors who have published 549 publications receiving 24316 citations.

Conformational Changes and Flexibility of DNA Devices Observed by Small-Angle X-ray Scattering

Abstract: Self-assembled DNA origami nanostructures enable the creation of precisely defined shapes at the molecular scale. Dynamic DNA devices that are capable of switching between defined conformations could afford completely novel functionalities for diagnostic, therapeutic, or engineering applications. Developing such objects benefits strongly from experimental feedback about conformational changes and 3D structures, ideally in solution, free of potential biases from surface attachment or labeling. Here, we demonstrate that small-angle X-ray scattering (SAXS) can quantitatively resolve the conformational changes of a DNA origami two-state switch device as a function of the ionic strength of the solution. In addition, we show how SAXS data allow for refinement of the predicted idealized three-dimensional structure of the DNA object using a normal mode approach based on an elastic network model. The results reveal deviations from the idealized design geometries that are otherwise difficult to resolve. Our results...

Ammonia sensing for enzymatic urea detection using organic field effect transistors and a semipermeable membrane

Abstract: Organic Field Effect Transistors (OFETs) are used to measure ammonia in solution via ammonia diffusion into the OFET channel. An increase in ammonia concentrations results in a decrease in transistor currents. The regeneration of the OFET current after ammonia uptake is slow, which allows us to read out the maximum ammonia dose which was applied. A 100 nm parylene-C layer serves as a semipermeable top gate dielectric. The parylene layer is functionalized with the covalently attached enzyme urease. The enzyme catalyses the hydrolysis of urea to ammonia and carbon dioxide, i.e. urea can be detected via its hydrolysis product ammonia. The sensitivity covers a range of physiological concentrations of urea, which are several mM.

Photocurrents in a Single InAs Nanowire/Silicon Heterojunction.

Abstract: We investigate the optoelectronic properties of single indium arsenide nanowires, which are grown vertically on p-doped silicon substrates. We apply a scanning photocurrent microscopy to study the optoelectronic properties of the single heterojunctions. The measured photocurrent characteristics are consistent with an excess charge carrier transport through midgap trap states, which form at the Si/InAs heterojunctions. Namely, the trap states add an additional transport path across a heterojunction, and the charge of the defects changes the band bending at the junction. The bending gives rise to a photovoltaic effect at a small bias voltage. In addition, we observe a photoconductance effect within the InAs nanowires at large biases.

Spin Seebeck effect at microwave frequencies

Abstract: We experimentally study the transient voltage response of yttrium iron garnet/platinum bilayer samples subject to periodic heating up to gigahertz frequencies. We observe an intrinsic cutoff frequency of the induced thermopower voltage, which characteristically depends on the thickness of the yttrium iron garnet film. The cutoff frequency reaches values of up to 350 MHz in a 50-nm-thick yttrium iron garnet film, but drops to below 1 MHz for several-micrometer-thick films. These data corroborate the notion that the magnon spectrum responsible for the spin current emission in the spin Seebeck effect can be shaped by tuning the thickness of the ferromagnetic layer.