Mikrofluidní zařízení vyrobené 3D tiskem – generátory kapek

Abstract

The Master thesis deals with study the of droplet forming in microfluidic devices made by FDM 3D printing method. The thesis consists of two parts, theoretical and experimental. The theoretical part mainly focuses on characterization of microfluidic devices, listing their advantages, disadvantages and the fields of practical use. A considerable focus is on droplet generators, their types and the options in which their behaviour may be interpreted. Subsequently, the theoretical part also touches on the topic of 3D printing methods, emulsions and CFD simulations. The experimental section is composed of two main parts. First of them is a study of selected surface active agents namely sodium lauryl sulfate, sodium oleate, and propylene glycol monostearate which were determined as usable for dispersion experiments. This study consists of measuring surface and interfacial tension of surfactant solutions on laboratory equipment Krüss K100 by Du Noüy method, evaluation of experimental data and determination critical micellar concentrations (CMC). The second part involves dispersion experiments in 4 microchips which are only different in size of the outlet channel. For evaluating the experimental image data, the special software ADM (Automated droplet measurement) is used. The size of formed droplets and difference in their behaviour influenced by the contrasting size of the outlet channel is studied. Distribution of size, velocity and distance between the flowing droplets are also analysed. The following is a list of the most important findings: - By 3D print it is possible to make microfluidics droplet generators which can produce monodisperse emulsions (coefficient of variation doesn’t exceed 4 %). - Size of formed droplets can be predicted by following equation: D=1,27-0,16⋅ln⁡(Qc/Qd -0,88) - Velocity of droplets is inversely proportional to size of outlet channel. - Velocity of droplets is approximately between the maximum and average velocity of fluid flow in the outlet channel (parabolic velocity flow profile).