Entwicklung von Mikro-Membranpumpen auf CVD-Diamantschichten

Abstract

In this thesis a process for the realization of microfluidic and micromechanic functional surface structures on CVD-diamond is developed. The concept is based on a CVD silicon oxide sacrificial layer, limited to a maximum thickness of ca. 5 µm due to thermal stress, which builds up during the diamond growth process. After the sacrificial structures have been overgrown, they are removed in an HF based wet etch step. To demonstrate the working principle, electromechanical (bimetallic actuator, membrane) and fluidic (channels, passive valves) functional elements are combined to form a membrane micropump with membrane features of 500 x 500 µm2 at a membrane thickness of approx. 2 µm. Fluidic and thermomechanic simulations where used to find the optimal geometric parameters for diffusor/nozzle efficiency and membrane deflection. Due to limitations of the structures height (oxide sacrificial layer), the throughput of the system is beyond practical measures. Therefore, first experiments on the introduction of alternative metal based sacrifical structures (plated copper) without mayor limitations in height are undertaken. Also, as an alternative to monolithic fabrication, a two component hybrid process with a fluid plate and a membrane plate is introduced.