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C. Zeilmann, T. Haas, A. Backes, U. Schmid:
"LTCC Based Microfluidic Mass Flow Sensor Concept";
Journal of Microelectronics and Electronic Packaging (invited), 9 (2012), 2; 87 - 96.

Low temperature cofired ceramics (LTCC) is established as a widespread platform for advanced functional ceramic circuits in many different applications, such as space, aviation, medical, and sensor technology. MLC (multi layer ceramics) based systems allow the integration of passive components, which leads to a high integration level. For microfluidic devices, the integration of 3D structures such as channels and chambers is necessary. Using LTCC will lead to integrating sensor elements due to high reliability, the good ceramic characteristics, and excellent physical properties. To realize 3D microchannels beyond the laboratory, adequate manufacturing processes are essential. This study proposes the realization of microfluidic channels and shows in which ways these can be realized by a range of newly developed manufacturing methods during the LTCC process. A benchmark of 3D laser structuring and two cold embossing technologies were investigated to show the benefits and also the limits of each technology. The sensor elements, which were directly integrated into the LTCC body, are based on PTC and resistor materials realized in thick film technology. The excellent performance of a microfluidic LTCC system will be shown based on a manufactured demonstrator. The final conclusion is that these established manufacturing and integration methods offer remarkable potential to meet the requirements for future circuit designs, where actual design concepts cannot solve all issues, in particular where harsh environmental conditions occur or a high integration concept is mandatory.