Materials Chemistry

Biography

Biography: Werner Karl Schomburg

Abstract

Ultrasonic fabrication is a new way to generate microfluidic chips. Micro channels are pro-duced by ultrasonic hot embossing with a commercially available ultrasonic welding machine in a few seconds. A stack of polymer films is placed onto a tool with protruding micro structures. The stack is pressed onto the tool and ultrasonic vibrations generate friction heat and melt the polymer. The polymer adapts to the shape of the micro structures on the tool and har¬dens again by cooling down after the ultrasound is switched off. Then a single micro patterned piece of polymer is removed from the tool. A new tool can be fabricated by milling of an aluminum plate within a few hours. Therefore, this process requires both investment costs of a few 10,000 € and cycle times of a few seconds. Besides this, the fabrication can be changed to a new design or a new polymer in a few hours or a few minutes, respectively. Nearly every thermoplastic polymer can be processed this way. By ultrasonic welding, micro channels generated by ultrasonic hot embossing are closed with a lid or another micro patterned layer. This way, chemical micro reactors, micro systems for bio-logical investigations and analysis chips for disease diagnosis have been fabricated. In Fig. 2 there are shown on the left a polymer chip including micro structures for intercepting bubbles, a mixer and a cuvette. In the middle of Fig. 2 there is seen a cut through the micro nozzle on a chemical micro reactor. The nozzle has a circular cross-section and was made of two ultra¬sonically hot embossed polymer layers welded on top of each other. On the right of the same figure there is shown a heat exchanger with three layers of micro channels on top of each other.