Serge Monneret

Complex ceramic-polymer composite microparts made by microstereolithography

In this paper we deal with the use of microstereolithography (/spl mu/SL) to produce solid freeform objects from computer-assisted-design files. The /spl mu/SL process is derived from stereolithography, and it is based on the photopolymerization through a dynamic mask generator of successive layers of photocurable resin, which permits us to produce accurate micro-objects with high aspect ratio and curved surfaces (due to the layer-by-layer nature of the process). This technology is extended to the manufacture of ceramic-polymer composite parts. To achieve this, we add dispersed alumina powder (at a volumic percentage of 24%) and a visible photoinitiator to a low viscosity diacrylate resin. The objects we made present interesting properties for microrobotic or microfluidic applications.

Microstereolithography using a dynamic mask generator and a noncoherent visible light source

Laser stereolithography deals with the manufacture of 3D objects that are made by space-resolved laser-induced polymerization. In order to obtain 3D micro-objects, we developed a new microstereolithography apparatus based on the use of a dynamic mask generator which allows the manufacture of a complete layer by only one irradiation, the part being manufactured layer by layer. This process is compared of a broad-band visible light source, that leads to the elimination of speckle effects resulting from the conventional use of a laser beam, and of a liquid crystal display as the dynamic mask generator. A lateral resolution of 2 micrometers has been demonstrated, and some examples of high aspect ratio micro-objects are presented.

Micro-scale rapid prototyping by stereolithography

A new process of microstereolithography to manufacture freeform solid three-dimensional micro-components with outer dimensions in the millimetre size range is presented. It corresponds to a layered micromachining, specially suited to rapid prototyping at the micro scale. Different kinds of materials can be employed, like pure polymers or alumina-based composites. The micromachine is mainly composed of a liquid crystal display as a dynamic mask generator and of a broad-band visible light source. The manufacture of complex three dimensional microparts demonstrates the possibilities of the process specially when concerned with composite alumina-based microstructures. Its availability to realise pure sintered alumina microcomponents is also shown.

Image upconversion from the visible to the UV domain: application to dynamic UV microstereolithography

We present what to our knowledge is a new application of optical frequency upconversion of images in quadratic materials to dynamic UV microstereolithography. A 150 x 150 point visible image transmitted by a liquid-crystal display was upconverted in a lithium triborate crystal, and the UV image was successfully used to polymerize a commercial stereolithographic resin.

New process for manufacturing ceramic microfluidic devices for microreactor and bioanalytical applications

The advances of the past few years in microreactors have demonstrated that microchips have numerous significant advantages with respect to cost, safety, throughput, kinetics and scale-up [1-3]. The whole aspect of heat management, enabling mass and heat transfer to be extremely rapid, leads to a higher level of reaction control and reactant manipulation at any one point within the chip.

Stereolithography and Micro-mechanics

Laser stereolithography deals with the manufacture of three-dimensional objects that are made by space-resolved laser-induced polymerization. In order to obtain three dimensional microobjects, we developed a new microstereolithography apparatus based on the use of a dynamic mask-generator which allows the manufacture of a complete layer by only one irradiation, the part being manufactured layer by layer. This process uses a broad-band visible light source, that leads to the elimination of speckle effects resulting from the conventional use of a laser beam. A lateral resolution of 2 μm * 2 μm has been demonstrated with this new process.