Ultrasonic hot embossing of polymers is an alternative to reduce fabrication costs of microreactors. An ultrasonic welding machine is used to melt a stack of thermoplastic foils and adapting them to a short-time milled aluminum mold showing the inversed design of the desired microfluidic cavities. Two micromixers were fabricated this way providing a low degree of axial dispersion and pressure loss. Stability analysis is successfully performed for a wide temperature range and high pressure. Mixing of colored aqueous solutions and neutralization reactions are implemented to both systems for defined volume flow rates and optically investigated via microscope. Reaction progress is automatically determined with a MATLAB script by reference to the consequential color change of the neutralization reaction with a color indicator. Typical mixing characteristics are identified for both mixers.

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The absorption and chemisorption of small bubbles with N 2 or CO 2 were investigated experimentally in aqueous and alkaline solutions. Different bubble sizes were studied ranging from 0.1 to 2.5 mm in alkaline concentrations of 0.1 mM to 1 M NaOH. The experiments were conducted in a device consisting of a converging microchannel with a down flowing liquid. Levitation positions of single bubbles were optically characterized. A correlation was developed for the drag force coefficient, C D , including wall effects based on the force equilibrium. A linear decrease of bubble diameters was identified with and without chemical reaction, which is referred to as a rigid bubble surface area. Measured Sherwood numbers agree well with the literature values for the investigated Reynolds number range.

Verkürzte Entwicklungszeiten chemischer Prozesse sind durch Laborexperimente und Erkenntnisse daraus möglich. Dies wird durch modulare Mikrosysteme und deren Standardisierung der Apparate vereinfacht. Kunststoffe bieten durch ihre variablen Materialeigenschaften die Anpassung an die jeweiligen Prozesse sowie kostengünstige Herstellung. Das modulare Konzept besteht aus ultraschallheißgeprägten PVDF‐Folien. Zwei mögliche Anordnungsvarianten werden bezüglich ihrer Charakteristiken und der Verbindungsarten einzelner Module diskutiert. Die Durchführung einer Neutralisationsreaktion zeigt die Flexibilität dieses modularen Systems hinsichtlich Prozessanforderungen.

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