Hydro-elastic interactions for shaping hydrodynamic properties in microfluidic flows

Abstract: Microfluidics is the science of small fluid flows through geometries with dimensions in the micrometer range. It has proven to be particularly useful in the fields of physics, chemistry and biology, as fluid flows governed by diffusion, and friction offer great control over crucial parameters. These parameters include temperature, concentration gradients, reaction kinetics, and mixing within the microscale environment. Since its inception, microfluidics has rapidly evolved from simple single-channel systems to sophisticated networks that enable parallelization of microfluidic processes within microfluidic devices. However, when comparing man-made microfluidic networks with prominent examples of microfluidic networks in nature, such as Physarum polycephalum (slime mold), it becomes clear that man-made networks are far from being able to perform processes that come close to the level of complexity of natural networks. Man-made fluid networks often lack the ability to adapt dynamically to changes and to self-regulate the processes that take place within them.
To overcome this limitation, it is desirable to make microfluidic devices more autonomous by enabling them to independently change their hydrodynamic behavior in response to stimuli. By integrating hydrogel elements into fluid networks, the channels that make up these networks can change their hydrodynamic properties in response to external stimuli. This enables the targeted manipulation of fluid flows within the channels. However, this approach requires the introduction of new materials and additional microfabrication steps.
To bridge the gap between the capabilities of artificial fluid networks (such as microfluidic devices) and their natural counterparts (such as the slime mold), fundamental concepts are explored in this thesis. Membranes are used as walls of microfluidic channels, which can manipulate the fluid flow field through hydro-elastic interactions with the passing fluid. This includes not only the purely hydro-elastic coupling of the channels, but also a stimulus response by swelling-induced buckling of the membrane.
The membrane interacting with the passing fluid can swell, leading to the formation of a sinusoidal deflection pattern. This pattern changes the hydraulic resistance of adjacent channels depending on the swelling capacity of the fluid. In order to generate a time-dependent change in the flow field, a traveling wave can be induced into the deflection pattern, altering the flow field of the fluid with frequencies from Hertz to kilohertz, depending on the applied pressure difference and the composition of the fluid. This results in a clock mechanism that has the potential to synchronize processes within fluid networks. This work presents concepts that enable fluid networks to work more autonomously. Particular emphasis is placed on the simple design of these concepts and their easy integration into microfabrication processes

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Universität Freiburg, Dissertation, 2024

Classification and Topics

• Keyword: Mikrofluidik ; Hydrodynamik

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2024
• Creator: Stamp, Claas-Hendrik
• Contributor: Pfohl, Thomas ; Hugel, Thorsten ; Albert-Ludwigs-Universität Freiburg. Physikalisches Institut ; Albert-Ludwigs-Universität Freiburg. Fakultät für Mathematik und Physik

Further information

• DOI: 10.6094/UNIFR/258053
• URN: urn:nbn:de:bsz:25-freidok-2580535
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:20 AM CEST