The combination of atomic force microscopy and Kelvin probe technology is a powerful tool to obtain high-resolution maps of the surface potential distribution on conducting and nonconducting samples. However, resolution and contrast transfer of this method have not been fully understood, so far. To obtain a better quantitative understanding, we introduce a model which correlates the measured potential with the actual surface potential distribution, and we compare numerical simulations of the three-dimensional tip-specimen model with experimental data from test structures. The observed potential is a locally weighted average over all potentials present on the sample surface. The model allows us to calculate these weighting factors and, furthermore, leads to the conclusion that good resolution in potential maps is obtained by long and slender but slightly blunt tips on cantilevers of minimal width and surface area.

The paper presents a new generation of torque-controlled lightweight robots (LWR) developed at the Institute of Robotics and Mechatronics of the German Aerospace Center. In order to act in unstructured environments and interact with humans, the robots have design features and control/software functionalities which distinguish them from classical robots, such as: load-to-weight ratio of 1:1, torque sensing in the joints, active vibration damping, sensitive collision detection, as well as compliant control on joint and Cartesian level. Due to the partially unknown properties of the environment, robustness of planning and control with respect to environmental variations is crucial. After briefly describing the main hardware features, the paper focuses on showing how joint torque sensing (as a main feature of the robot) is consequently used for achieving the above mentioned performance, safety, and robustness properties.

Sheets and rational synthesis are not like fire and water! Hexafunctional terpyridine monomers can be laterally connected by metal salts to result in a mechanically stable, sheetlike entity that can be transferred from the air/water interface to a solid substrate (see the folded, ca. 1.4 nm thin film) and spanned over micrometer‐sized holes. This result is considered an important step on the way to 2D polymers.

Imaging temperature fields at the nanoscale is a central challenge in various areas of science and technology. Nanoscopic hotspots, such as those observed in integrated circuits or plasmonic nanostructures, can be used to modify the local properties of matter, govern physical processes, activate chemical reactions and trigger biological mechanisms in living organisms. The development of high-resolution thermometry techniques is essential for understanding local thermal non-equilibrium processes during the operation of numerous nanoscale devices. Here we present a technique to map temperature fields using a scanning thermal microscope. Our method permits the elimination of tip-sample contact-related artefacts, a major hurdle that so far has limited the use of scanning probe microscopy for nanoscale thermometry. We map local Peltier effects at the metal-semiconductor contacts to an indium arsenide nanowire and self-heating of a metal interconnect with 7 mK and sub-10 nm spatial temperature resolution.

During the last decade, various efforts have been undertaken to enhance the resolution of optical microscopes, mostly because of their importance in biological sciences. Herein, we describe a method to increase the resolution of fluorescence microscopy by illuminating the specimen with a mesh-like interference pattern of a laser source and electronic postprocessing of the images. We achieve 100-nm optical resolution, an improvement by a factor of more than 2 compared with standard fluorescence microscopy and of 1.5 compared with confocal scanning.

Covalent monolayer sheets in 2 hours: spreading of threefold anthracene-equipped shape-persistent and amphiphilic monomers at the air/water interface followed by a short photochemical treatment provides access to infinitely sized, strictly monolayered, covalent sheets with in-plane elastic modulus in the range of 19 N/m.

We discuss practical aspects of Kelvin probe force microscopy ͑KFM͒ which are important to obtain stable images of the electric surface potential distribution at high spatial resolution ͑Ͻ100 nm͒ and high potential sensitivity ͑Ͻ1 mV͒ on conducting and nonconducting samples. We compare metal-coated and semiconducting tips with respect to their suitability for KFM. Components of the metal coating can become detached during scanning, introducing sudden offset jumps in the potential maps ͑typically up to 350 mV between adjacent scan lines͒. However, n-doped silicon tips show no substantial tip alterations and, therefore, provide a stable reference during the experiment ͑offset jumps typically up to 40 mV between adjacent scan lines͒. These semiconducting tips must be electrically connected via contact pads. We use InGa and colloidal silver pads which are easily applied to the substrate supporting the cantilever and have a low enough differential contact resistance ͑350 ⍀ and 2.2 k⍀, respectively͒. Furthermore, we introduce a simple procedure to fine tune the feedback which detects the electric surface potential and show how the basic KFM setup has to be modified to gain access to the necessary control signals.

We identify the dynamics of an atomic force microscope (AFM) in order to design a feedback controller that enables faster image acquisition at reduced imaging error compared to the now generally employed proportional integral differential (PID) controllers. First, a force model for the tip–sample interaction in an AFM is used to show that the dynamic behavior of the cantilever working in contact mode can be neglected for control purposes due to the relatively small oscillation amplitude of the cantilever in response to a defined topography step. Consequently, the dynamic behavior of the AFM system can be reduced to the behavior of the piezoelectric scanner making the design of a model based controller for the AFM possible. Second, a black box identification of the scanner of a commercial AFM (Nanoscope IIIa, Digital Instruments) is performed using subspace methods. Identification yields a mathematical model of the scanner which allows us to design a new controller utilizing H∞ theory. Finally, this controller is implemented on an existing AFM and operated in contact mode. We demonstrate that such an H∞-controlled AFM system, while scanning at rates five times faster than conventional PID-controlled systems, operates with reduced measurement error and allows scanning at lower forces.