Evaluation of Experimental Methods to Determine the Pump Chamber Volume of Metal-Based Micro Diaphragm Pumps

This thesis explores the development of a micropump-based system for the extraction of interstitial fluid (ISF), aiming to enable a minimally invasive and wearable diagnostic platform. Two main objectives were addressed. First, the design and validation of a first prototype that integrates hollow silicon microneedles with piezoelectrically actuated metal-based micro diaphragm pumps for miniaturized, suction-driven ISF extraction. Second, the experimental determination and correlation of key micropump performance parameters, particularly the compression ratio, which is defined as ratio between the displaced stroke volume and the pump chamber dead volume. These parameters directly influence fluidic performance and bubble tolerance and are especially critical in biomedical applications. A functional proof-of-concept ISF extraction prototype was successfully developed, enabling direct transfer of negative pressure through the microneedles onto the tissue. The system combines compactness with controllable suction pressure build-up and is therefore suitable for future ex-vivo and in-vivo testing. Two different prototype versions are presented: an
extraction-only variant and a fluid routing extraction and ejection variant. The study reveals significant variability among micropump samples with differing pretension voltages and fabrication histories, which strongly influences compression ratio, valve quality, and overall pump performance. The results demonstrate that individual device profiling is essential, as performance depends not only on electrical actuation parameters but also on process-induced deviations. Furthermore, an experimental framework for pump chamber volume analysis was established, providing a validated basis for predictive micropump characterization.