LIGA structure

Figure 11.27 Spectro-electrochemical ceU for simultaneous measurements of ESR and UV/vis spectra. (1) Quartz rod, (2) quartz pipes, (3) platinum tube, (4) electrolyte in, (5) electrolyte out, (6) Ag wire contact to LIGA structure, and (7) Ag tube WE, RE, and CE are working, reference,...

Fiber optical detection systems require structures with extremely high precision. Therefore the LIGA technique is a powerful tool to fulfill these requirements. LIGA structuring enables the design of a miniaturized "optical bench system". Precise positioning structures for ball lenses or fibers, for polarizers or other elements of various materials can be achieved. Figure 5 shows an optical detection system which can be used for measurements of UV-absorption or fluorescence. 

Zhu et al. [76] designed and fabricated microfluidic devices on polymethylmethacrylate (PMMA) substrates for electrochemical analysis applications using an improved UY-LIGA process. The microchannel structures were transferred from a nickel mold onto the plastic plates by the hot embossing... 

The NaTl-type structure is the prototype for Zintl phases, which are inter-metallic compounds which crystallize in typical non-metal crystal structures. Binary AB compounds LiAl, LiGa, Liln and Naln are both isoelectronic (isovalent) and isostructural with NaTl. In the Li2AlSi ternary compound, A1 and Si form a diamond-like framework, in which the octahedral vacant sites of the A1 sublattice are filled by Li atoms, as shown in Fig. 13.7.2(b). 

Micromolding (LIGA ) Patterning of three-dimensional resist structures by high-aspect-ratio lithography, fabrication of a mold by electroplating... 

A combined fabrication technology made possible through a sacrificial layer technique was developed to obtain partly or totally movable microstmctures together with fixed structures on a single substrate. Many practitioners consider this ability to be the hall mark of the LIGA process. 

The substrate is first coated, for instance, via electroless or physical vapor deposition with a thin (< 1 pm) metallic layer, which in turn is patterned by photolithography and wet etching. This layer serves two roles, as a plating base and as an electrically conducting layer for the finished structures. In the subsequent step a sacrificial layer, of about 5 pm in tliickness, is deposited on the substrate and also patterned by photolithography and wet etching. Titanium is used most often as the sacrificial material because it adheres well to the resist and to the electrodeposited layer and can be etched with hydrofluoric acid that does not attack other materials such as chromium, silver, nickel, copper, and which are usually used in the LIGA process. 

The plastic molding process may be combined with deep etch X-ray lithography to fabricate microstructures with different shapes in the third dimension" In the first step, only the upper part of a very thick resist layer is patterned with the embossing technique using a mold insert fabricated by the standard LIGA process. The relief structure obtained by this first patterning process is subsequently exposed to synchrotron radiation through a precisely... 

The present work will only consider the electronic properties of those Zintl phases which crystallize in the B32 structure. Binary B32 Zintl phases are formed by the AB compounds LiAl, LiGa, Liln and Naln, by the prototype NaTl, and by the AB compounds LiZn and LiCd. Ternary systems, which crystallize in this structure, are found for alloys ABi-,Cx, for which at least one boundary compound AB or AC crystallizes in the NaTl type of structure. 

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