Neue Entwicklungen beim Hohlkatoden‐Gasflusssputtern. New Developments in Hollow Cathode Gas Flow Sputtering

The gas flow sputter technique was invented a few years ago particularly for the inexpensive fabrication of sophisticated ceramic layers. Meanwhile, it has matured and become increasingly powerful. Today it is on the verge of being applied in industrial fabrication processes. The present article gives an overview over the method, its characteristics and the numerous applications.     

Strain‐Mediated Phase Stabilization: A New Strategy for Ultrastable α‐CsPbI3 Perovskite by Nanoconfined Growth

All‐inorganic cesium lead triiodide (CsPbI₃) perovskite is considered a promising solution‐processable semiconductor for highly stable optoelectronic and photovoltaic applications. However, despite its excellent optoelectronic properties, the phase instability of CsPbI₃ poses a critical hurdle for practical application. In this study, a novel stain‐mediated phase stabilization strategy is demonstrated to significantly enhance the phase stability of cubic α‐phase CsPbI₃. Careful control of the degree of spatial confinement induced by anodized aluminum oxide (AAO) templates with varying pore sizes leads to effective manipulation of the phase stability of α‐CsPbI₃. The Williamson–Hall method in conjunction with density functional theory calculations clearly confirms that the strain imposed on the perovskite lattice when confined in vertically aligned nanopores can alter the formation energy of the system, stabilizing α‐CsPbI₃ at room temperature. Finally, the CsPbI₃ grown inside nanoporous AAO templates exhibits exceptional phase stability over three months under ambient conditions, in which the resulting light‐emitting diode reveals a natural red color emission with very narrow bandwidth (full width at half maximum of 33 nm) at 702 nm. The universally applicable template‐based stabilization strategy can give in‐depth insights on the strain‐mediated phase transition mechanism in all‐inorganic perovskites.     

Stable Non‐Covalent Large Area Patterning of Inert Teflon‐AF Surface: A New Approach to Multiscale Cell Guidance

Micro‐ and nano‐patterning of cell adhesion proteins is demonstrated to direct the growth of neural cells, viz. human neuroblastoma SHSY5Y, at precise positions on a strongly antifouling substrate of technolological interest. We adopt a soft‐lithographic approach with oxygen plasma modified PDMS stamps to pattern human laminin on Teflon‐AF films. These patterns are based on the interplay of capillary forces within the stamp and non‐covalent intermolecular and surface interactions. Remarkably, they remain stable for several days upon cell culture conditions. The fabrication of substrates with adjacent antifouling and adhesion‐promoting regions allows us to reach absolute spatial control in the positioning of neuroblastoma cells on the Teflon‐AF films. This patterning approach of a technologically‐relevant substrate can be of interest in tissue engineering and biosensing.     

Remote Sensors with Self‐Test: New Opportunities to Improve the Performance of Physical Transducers

When addressing the question on how to operate sensors in a remote environment, i.e., in non‐accessible places, the issue of reliability becomes of extreme importance. Especially in the case where miniaturisation is essential, often the physical geometries become that small that the sensor performance degrades to yield only very weak signal levels. Matching circuits are an essential element. Monitoring physical quantities from a remote and difficult to access location requires high standards for the sensors and their circuits involved: it is essential that the data remains reliable at all times. This is a hard requirement, and many sensors used in such applications cannot cope with such severe specifications, as there are: low drift, high stability in time, immunity to cross sensitivies, etc. This paper focuses on a double solution: first by adding circuitry improving the intelligence of the entire sensor system. Secondly, it is shown how the sensor design in itself can be modified to improve the interface circuit performance. An essential element is the addition of built‐in self‐test features to verify the correct operation of the sensor at any given moment in time. Crucial in these novel developments is that the measurand itself is used to verify the operation of the sensor, and not a related actuation as is done in many existing devices.