Drainage during Condensation on Microgrooved Biphilic Surfaces.

In this work, we investigate and compare the condensation behavior of hydrophilic, hydrophobic, and biphilic microgrooved silicon samples etched by reactive ion etching. The microgrooves were 25 mm long and 17-19 μm deep with different topologies depending on the etching process. Anisotropically etched samples had 30 μm wide rectangular microgrooves and silicon ridges between them.

Intercalation-free, fast switching of mesoporous antimony doped tin oxide with cathodically coloring electrochromic dyes.

Mesoporous nanoparticle layers of transparent conductive oxides (TCOs) with anchored organic dyes are of great interest for electrochromic applications. Herein, we prepared mesoporous layers of antimony doped tin oxide (ATO) consisting of only 5 nm large particles with a low Sb concentration (2% antimony). The particles were prepared a modified synthesis procedure based on hexahydroxostannate and pure Sb(v) hexahydroxoantimonate(v).

Electrochromic graduated filters with symmetric electrode configuration.

Graduated optical filters are commonly used for spatial image control as they are capable of darkening the overexposed parts of the image specifically. However, they lack flexibility because each filter has a fixed transmission distribution. We herein present a fully controllable graduated filter based on the electrochromic device.

Tunable graduated filters based on electrochromic materials for spatial image control.

Passive graduated filters with fixed absorption profile are currently used in image recording to avoid overexposure. However, a whole set of filters with prescribed gradients is required to cope with changing illumination conditions. Furthermore, they demand mechanical adjustment during operation.

Complementary hybrid electrodes for high contrast electrochromic devices with fast response.

Fast switching 'transparent-to-black' electrochromic devices are currently under investigation as potential candidates in modern applications like e-papers or with additional functionality as ultracompact iris or switchable neutral filter in camera systems. However, recent electrochromic devices show either a lack of contrast or slow response times. To overcome these deficiencies we focus on a careful material composition of the colouring hybrid electrodes in our device.

Exploiting Direct Laser Writing for Hydrogel Integration into Fragile Microelectromechanical Systems.

The integration of chemo-responsive hydrogels into fragile microelectromechanical systems (MEMS) with reflective surfaces in the micron to submicron range is presented. Direct laser writing (DLW) for 3D microstructuring of chemoresponsive "smart" hydrogels on sensitive microstructures is demonstrated and discussed in detail, by production of thin hydrogel layers and discs with a controllable lateral size of 2 to 5 µm and a thickness of some hundred nm. Screening results of polymerizing laser settings for precision microstructuring were determined by controlling crosslinking and limiting active chain diffusion during polymerization with macromers.

Electrically Reconfigurable Micromirror Array for Direct Spatial Light Modulation of Terahertz Waves over a Bandwidth Wider Than 1 THz.

We report the design, fabrication and experimental investigation of a spectrally wide-band terahertz spatial light modulator (THz-SLM) based on an array of 768 actuatable mirrors with each having a length of 220 μm and a width of 100 μm. A mirror length of several hundred micrometers is required to reduce diffraction from individual mirrors at terahertz frequencies and to increase the pixel-to-pixel modulation contrast of the THz-SLM. By means of spatially selective actuation, we used the mirror array as reconfigurable grating to spatially modulate terahertz waves in a frequency range from 0.

Depth of focus analysis of optical systems using tunable aperture stops with a moderate level of absorption.

The size of the aperture stop of a lens is a major parameter to define, e.g., the depth of focus of an optical imaging system.

Tailoring the interface of hybrid microresonators in viscid fluids enhances their quality factor by two orders of magnitude.

The application of microresonators in fluids is predominantly constrained by the strong damping caused by the viscid drag and the additional inertia of the liquid in the interfacial layer. In this paper we propose the new concept of partial wetting that exploits another property of liquids, its surface energy, to adapt physically the interface of the microresonator to the liquid by the formation of a meniscus. First experiments performed with technically simple batch-fabricated prototypes validate the potential of partial wetting as a vital route to improve the quality factor of microresonators in viscid fluids to values up to 600 exceeding those of conventional microresonators by almost two orders of magnitude.

Influence of electrode size and geometry on electrochemical experiments with combined SECM-SFM probes.

Gold electrodes integrated into silicon scanning force microscopy (SFM) probes allow the acquisition of spatially correlated data for sample morphology (via SFM) and local electrochemical reactivity via scanning electrochemical microscopy (SECM). The lateral resolution of both techniques is controlled by different properties of the integrated probes. The topographic tracking provided by the SFM mechanism allows the realization of very small working distances for the SECM measurements.

High-frequency micromechanical columnar resonators.

High-frequency silicon columnar microresonators are fabricated using a simple but effective technological scheme. An optimized fabrication scheme was invented to obtain mechanically protected microcolumns with lateral dimensions controlled on a scale of at least 1 μm. In this paper, we investigate the influence of the environmental conditions on the mechanical resonator properties.

Analysis of RNA flexibility by scanning force spectroscopy.

Scanning force spectroscopy was used to measure the mechanical properties of double stranded RNA molecules in comparison with DNA. We find that, similar to the B-S transition in DNA, RNA molecules are stretched from the assumed A' conformation to a stretched conformation by applying a defined force (plateau force). The force depends on the G + C content of the RNA and is distinct from that required for the B-S transition of a homologous DNA molecule.