A study devoted to the design and fabrication of microgrippers using the LIGA technique is described in this paper. The design method is presented and validated by the use of finite-element analysis. Technological topics are detailed to illustrate the fabrication process. Also, experimental data concerning the mechanical behaviour of one of the microgrippers are reported. These data are used to improve the previous finite-element analysis. Finally, a comparison between experiments and theoretical predictions is discussed.

Microreactors are considered a new opportunity for R&D operations and for the production of hazardous or ultrapure materials where and when they are needed. Most chemical reactions are enhanced by a catalytic process involving a porous support for the catalyst. A microstructure exhibiting a fractal property is proposed as a porous network. A LIGA technique is used to manufacture a number of such structures. Limits and difficulties occurring are discussed.

Most of the presently known microstructures are still fabricated using silicon-based technologies. However, in the case of fabrication using anisotropic etching, geometrical limitations due to the crystallographic nature of silicon prevent the design of any in-plane structure shapes. If microsystems, built by means of reactive ion etching and sacrificial layer technology do have freedom for lateral geometry, they are limited to a few micrometers height only. Nevertheless, and in spite of difficulties to always answer the demands in the best way, real microsystemsare produced by these techniques and are currently present on the market. To overpass these limitations, other technologies have been studied and developed in recent years. Among them the LIGA process (German acronym for Lithography, Electroplating, Molding), which uses synchrotron radiation and in particular its hard X-Ray spectrum, is certainly the most promissing one regarding to, very high aspect ratio, submicron precision, arbitrary patternning and mass production capabilities. Furthermore, LIGA can handle a large variety of materials to fabricate microsystems.

This paper is devoted to the description of a low cost microfabrication process for the realization of deep etch X-ray lithography (DEXRL) masks. These masks are composed of a 15 mu m thick silicon membrane supporting gold absorbers which are typically 12 to 16 mu m thick. The resolution of such masks is limited to 2-4 mu m, but they allow irradiation up to 2 mm of polymethylmethacrylate (PMMA) by using hard X-ray synchrotron radiation. Theoretical results about dosimetric parameters for the PMMA irradiation are presented. Results obtained with these masks are also given. The purpose of this study is the realization of low cost micromechanical components using the LIGA technique.