J. Döpper

Gear pumps using micro gear wheels with diameters of 596 and and a height of have been realized at IMM by means of a combination of LIGA technology and precision engineering. Using oil as pumping medium the pumps achieve back pressures of more than 1200 hPa and flow rates of up to . The self-filling pumps tolerate air bubbles and particles contained in the working medium. The gear pumps displace 82 and 213 nl respectively per revolution, i.e. they offer the possibility of very precise dosing of viscous fluids, such as oil.

We present a new membrane micropump fabricated by micro mold injection and laser based techniques. Due to an innovative pump design featuring an extremely small internal volume and a large compression ratio the pumps are the first micropumps to combine outstanding technical performance with a really easy handling. The pumps work equally well with gases and liquids and exhibit a very reliable self-filling behavior with liquids. Pumping water we have achieved maximum pump rates of 400 /spl mu/l/min and a maximum back pressure of 2100 hPa. Using air the pumps can build up pressures of up to 500 hPa and generate a maximum flow rate of 3.5 ml/min. The maximum vacuum the pumps can create amounts to 350 hPa. Due to the use of replication based fabrication techniques and optimized assembly methods, the pump design has the potential for production costs on the order of 5 DM. The new micropump is being manufactured in a small series production and is available for industrial evaluation.

Miniaturized reaction systems offer many advantages for a large number of applications in chemical engineering and biotechnology. The very large surface-to-volume ratio of miniaturized fluidic components allows for a significantly enhanced process control and heat management, enabling the performance of chemical reactions in quite unusual reaction regimes. Miniaturized chemical systems offer unique possibilities for the distributed point-of-use production of toxic or explosive chemicals. The extremely large number of syntheses necessary for the development of new, for example pharmaceutical, products, demands the use of automated processing systems capable of handling very small amounts of liquids. Current microfabrication techniques offer possibilities to fabricate high precision microfluidic components, like static mixers, heat exchangers and micropumps from a large variety of function adapted materials. Improvements of the microstructuring capabilities of traditional precision mechanics techniques, like spark erosion based processes, lead to a significant enhancement of the range of materials to be used for the construction of micro reaction systems.

Industrial interest in micro-fabrication techniques has mushroomed in the wake of recent advances in microtechnology, notably LIGA technology which provides a cheap and effective route to the mass fabrication of complex microstructures. At the heart of LIGA technology is the injection moulding process. This paper investigates current state-of-the-art injection moulding simulation software for use as design tools in the development of micro-parts. We have investigated the flow of poly(oxymethylene) in 400 um wide channels of rectangular cross-section (depth 40-500 uin) and under a range of injection pressures. The flow lengths obtained were found to be in good agreement with computed values. Simulation results are also presented concerning the filling of components for a micro-pump.