Trench-first approach

As compared to electrical SPL, a broader range of materials becomes accessible for surface modifications using mechanical means. Two different approaches have been developed based on SFM surface scratching and material transfer. In the first approach, a scratch or trench of a defined width and depth can be produced by dragging the tip across the sample under controlled load and speed. In the second and more elegant approach, small portions of the sample, e.g. molecules and particles, are picked up by the tip, lifted and transferred to another region of the surface. 

Another approach to fabrication of structures with vertical walls is by simultaneous electrochemical etching of pores and trenches first introduced by Geppert et al. (2006). Forming a closed contour, the trenches define the sacrificial parts of the structure, which fall out from a sample after the substrate is removed. Figure 9 shows a schematic of the method and a bar of a 2D photonic crystal, produced by removal of sacrificial parts of the sample. 

The mass spectrometer is assembled from four wafers, three silicon and one glass wafer, hermetically sealed by anodic bonding The geometries of the orifice and the plasma electrodes are fabricated via anisotropic etching of Si by KOH The plasma chamber for this first approach was drilled into the Pyrex wafer For the electrodes of the mass separator a deep anisotropic plasma etching process is used by which perpendicular trenches more than 200 im deep with micrometer tolerances can be generated The electrodes are metallized for a defined potential within the separator... 

These pressure tests should be seen in the context of the mechanical stresses and subsequent failures in the field. In spite of all precautions on installation it must be assumed that pipes will be damaged, backfill and trenches will differ from those specified, welds may be imperfect and there will be bending stresses. Poor installation practice has been the principal cause of service failures, particularly of PVC pipe, and when installed correctly pipes taken from service (now 40 years) show no evidence of deterioration. In addition, polymers have improved greatly since pipes were first manufactured. Marshall and co-workers [2] describe the situation in more detail and recommend an approach to testing based on fracture mechanics. 

Increasing the initial catalyst coverage to 0.05 3 is predicted to result in near optimal superfilling behavior, as shown in Figure 2.36c. Enrichment at the bottom comers leads to rapid formation of first the V-notch and then the nearly flat bottom. As in the other simulations, the advancing bottom surface accelerates further as it collects catalyst from the eliminated sidewall areas. It also exhibits subtle oscillations in shape associated with the continual translation of catalyst from the sidewalls to the bottom surface. The oscillations are also detailed in the analytical solution of feature filling. The catalyst coverage approaches unity as the bottom surface reaches the top of the trench. 

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