Apart from its relevance in applications, this process goes along with the formation of characteristic DNA concentration patterns, visible in the figure at the left. Please find below older news relating to research at the Institute for Nano- and Microfluidics. Intermediate wetting states on superhydrophobic surfaces. Philippe Bourrianne Princeton Verified email at princeton.edu. DNA molecules can be concentrated by electrophoretic accumulation at an interface between two immiscible polymer solutions. A: Alarich-Weiss-Straße 10, L2|06 111, 64287 Darmstadt, GER T: +49 6151 16-24276. Now imaging shrinking the diameter of the wine glass to one millimeter. At a microscopic scale, surfactants, molecules attached to the interface between two fluids, can suffer the same fate, immobilizing the interface upstream of an obstacle. TU Darmstadt incorporates diverse science cultures to create its characteristic profile. Herzlich willkommen am Fachgebiet Nano- und Mikrofluidik. M. Dietzel and S. Hardt, Electroosmotic flow in small-scale channels induced by surface-acoustic waves, Physical Review Fluids 5 (2020), 123702. Klingenberg, Dario ; Oberlack, Martin ; Pluemacher, Dominik (2020): Symmetries and turbulence modeling. † Email address for correspondence: hardt@nmf.tu-darmstadt.de. Hongya Geng UCAS, ICCAS, Tsinghua, ICL Verified email at imperial.ac.uk. ‘Super-hydrophobic’ surfaces with embedded gas pockets have been suggested for reducing drag on objects moving through water. These liquid rings finally collapse and form plugs that are propelled along the capillary tube by evaporation. Microfluid Nanofluid 24, 41 (2020). Our research extends over a broad thematic spectrum and combines experimental, theoretical and numerical approaches. DOI: 10.1103/PhysRevApplied.13.014015. Jérôme F.L. Below, the same research outputs are grouped by subject. For a small particle inside a gas, the fluid dynamics of such problems becomes very involved, since the Navier-Stokes equation is no longer applicable. 6 Intitut für Angewandte Geowissenschaften, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt, Germany. Reference: C. Lv, S. N. Varanakkottu, and S. Hardt, Liquid plug formation from heated binary mixtures in capillary tubes, Journal of Fluid Mechanics 889 (2020), A15. Up to now, the electrokinetic effects due to SAWs have remained largely unexplored. Stability and collapse of holes in liquid layers - Volume 855 - Cunjing Lv, Michael Eigenbrod, Steffen Hardt www.nmf.tu-darmstadt.de. Via the charges created at the gas-liquid interfaces, the flow velocity can be increased by more than a factor of 10 compared to unstructured surfaces. You are here: TU Darmstadt; Maschinenbau; Nano- and Microfluidics; Home; Institute for Nano- and Microfluidics. Bird, G. A. In addition, the flow is entirely pH-independent. References (Subscription Required) Click to Expand. We have studied this phenomenon based on experiments and theory. We have studied the transfer of chemical species between the two reservoirs mediated by the droplet. B. Rofman, S. Dehe, V. Frumkin, S. Hardt, and M. Bercovici, Intermediate states of wetting on hierarchical superhydrophobic surfaces, Langmuir 36 (2020), 5517−5523. ‡ Corresponding author: hardt@nmf.tu-darmstadt.de; Article Text (Subscription Required) Click to Expand. Sitemap Therefore, such a pump may be used for gas separation. The method is sketched in the schematic on the left. Surface acoustic waves (SAW) are widely used in microfluidics for transporting and mixing liquids. We find a multitude of intermediate states between the classical Cassie and Wenzel states. pp. Journal of Fluid Mechanics 883, 47 (2020). DOI: 10.1103/PhysRevLett.124.064501, Tutorium „CFD-based simulation and optimization of microfluidic components“, This tutorium will equip students with the basic methodology needed to design and optimize microfluidic components on the computer. Click here for details, Species transfer using small droplets as carriers. Nano- and Microfluidics B. Rofman, S. Dehe, V. Frumkin, S. Hardt, and M. Bercovici, Intermediate states of wetting on hierarchical superhydrophobic surfaces, Langmuir 36 (2020), 5517−5523. Weian Sheng Airbnb, Intel, University of Florida Verified email at airbnb.com. Institute for Nano- and Microfluidics. Link: https://doi.org/10.1017/jfm.2019.921. DOI: 10.1017/jfm.2020.80, Pattern formation in layers of DNA molecules. Steffen Hardt Professor, TU Darmstadt Потвърден имейл адрес: nmf.tu-darmstadt.de. Return to institution outputs. ‡ hardt@nmf.tu-darmstadt.de; Article Text (Subscription Required) Click to Expand. Supplemental Material (Subscription Required) Click to Expand. References (Subscription Required) Click to Expand. A summary of the main results can be found here. Microfluid Nanofluid 24, 41 (2020). Therefore, SAW-induced EOF may be useful as a method for pumping liquids through small scale channels. Nanoscale gas kinetics, electrokinetics, interfacial flows, wetting phenomena and biomolecular separation belong to our areas of work. Reference: P. Goswami, T. Baier, S. Tiwari, C. Lv, S. Hardt, and A. Klar, Drag force on spherical particle moving near a plane wall in highly rarefied gas. Tobias Baier Center of Smart Interfaces, TU Darmstadt Verified email at nmf.tu-darmstadt.de. In that case, ring-like structures are formed from the film. Formation of small droplets inside larger droplets, Microfluidic chip with two-phase flow for DNA or protein separation in an electric field, Wetting transition on a superhydrophobic surface, Electroosmotic flow along a superhydrophobic surface induced by a gate electrode. Fachgebiet Nano- und Mikrofluidik – Herzlich willkommen am Fachgebiet Nano- und Mikrofluidik. Surface acoustic waves (SAW) are widely used in microfluidics for transporting and mixing liquids. Working area(s) Emeritus. Link: https://doi.org/10.1017/jfm.2019.921. In that case, the viscosity coefficients represent the dissipation due to the presence of particles or surfactants in an average manner. Usually, viscosity is a quantity associated with the bulk of a fluid. S. 025108, ISSN 1070-6631, DOI: 10.1063/1.5141165, [Online-Edition: https://doi.org/10.1063/1.5141165], [Artikel] We have found a solution to this problem, where a droplet with a diameter of the order of 5 µm serves as carrier for the cargo. A summary of the main results can be found here. Formation of small droplets inside larger droplets, Microfluidic chip with two-phase flow for DNA or protein separation in an electric field, Wetting transition on a superhydrophobic surface, Electroosmotic flow along a superhydrophobic surface induced by a gate electrode. Contact. Sort. This kind of separation of gas species by mass or size plays an important role for many applications in chemical engineering. The course language will be English. Dr. Dharmendra Tripathi Associate Professor, Mathematics, National Institute of Technology Uttarakhand Verified email at nituk.ac.in. T. Baier and S. Hardt, Influence of insoluble surfactants on shear flow over a surface in Cassie state at large Péclet numbers, Journal of Fluid Mechanics 907 (2020), A3. The course language will be English. Babovsky, H. & Illner, R. 1989 A convergence proof for Nanbu’s simulation method for the full Boltzmann equation. 7 Physics of Surfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, 64287 Darmstadt, Germany. SAWs are acoustic waves travelling along the interface between a solid and a fluid. Nature Index 2020 Artificial Intelligence. Upon touching the reservoir, the droplet reverses its charge and its direction of motion. Seyed Mahmood Mousavi High Performance Computing center (HPCC) Потвърден имейл адрес: shirazu.ac.ir. 1994 Molecular Gas Dynamics and the Direct Simulation of Gas Flows. Title. Office. Issue. Surfactants can immobilize fluid–liquid interfaces under shear stress. https://www.fdy.tu-darmstadt.de/fdy/fdystaff/details_17472.de.jsp SIAM J. Numer. In addition, the flow is entirely pH-independent. S. Dehe, B. Rofman, M. Bercovici, and S. Hardt, Electro-osmotic flow enhancement over superhydrophobic surfaces, Physical Review Fluids 5 (2020), 053701. Via the charges created at the gas-liquid interfaces, the flow velocity can be increased by more than a factor of 10 compared to unstructured surfaces. DOI:10.1017/jfm.2019.921. Steffen Hardt Professor, TU Darmstadt Verified email at nmf.tu-darmstadt.de. As a stream encounters an obstacle, floating debris sometimes piles up in front of the obstacle, forming a dense layer on the water surface. The method is sketched in the schematic on the left. Unsere Forschung erstreckt sich über ein breites Themenspektrum und kombiniert experimentelle, theoretische und numerische Ansätze. We have experimentally studied the concentration patterns and formulated a theory describing the pattern formation. Ehsan Ro Institute for Nano- and Microfluidics (NMF), TU Darmstadt . Nano- and Microfluidics You are here: TU Darmstadt; Maschinenbau; Nano- and Microfluidics; Sitemap. Together with cooperation partners from the Technion/Israel, we have studied the wetting states of hierarchical superhydrophobic surfaces, consisting of an array of micropillars that is decorated with nanoparticles. We have theoretically studied the EOF induced by SAWs and found that in small-scale channels, the EOF velocity may significantly exceed the velocity due to the acoustic field. Research; Relationships; 1 August 2019 - 31 July 2020. Reference: S. Hardt, J. Hartmann, S. Zhao, and A. Bandopadhyay, Electric-field-induced pattern formation in layers of DNA molecules at the interface between two immiscible liquids, Physical Review Letters 124 (2020), 064501. M. Eigenbrod and S. Hardt, The effective shear and dilatational viscosities of a particle-laden interface in the dilute limit, Journal of Fluid Mechanics 903 (2020), A26. Together with cooperation partners from the Technion/Israel, we have studied the electroosmotic flow along superhydrophobic surfaces, augmented by gate electrodes. Song Jinlong The School of Mechanical Engineering, Dalian University of Technology Verified email at dlut.edu.cn. We find a multitude of intermediate states between the classical Cassie and Wenzel states. Principal institution: Darmstadt University of Technology (TU Darmstadt) Region: Global Subject/journal group: All The table to the right includes counts of all research outputs for Institute for Nano- and Microfluidics (NMF), TU Darmstadt published between 1 June 2019 - 31 May 2020 which are tracked by the Nature Index. With this in mind, we investigated the impact that surfactants have on this mechanism and found that parts of the gas-water interface become ‘solidified’ by surfactant pile-up. These liquid rings finally collapse and form plugs that are propelled along the capillary tube by evaporation. We have computed the corresponding drag force on a particle and find that it is much lower than the one predicted by the Navier-Stokes equation. The transition from the Cassie state to these intermediate states is partially reversible. 26 (1), 45 – 65. References (Subscription Required) Click to Expand. Reference: M. Shojaeian and S. Hardt, Mass transfer via femtoliter droplets in ping-pong mode, Physical Review Applied 13 (2020), 014015. Baier, T., Hardt, S. Gas separation in a Knudsen pump inspired by a Crookes radiometer. As a stream encounters an obstacle, floating debris sometimes piles up in front of the obstacle, forming a dense layer on the water surface. Reference: S. Hardt, J. Hartmann, S. Zhao, and A. Bandopadhyay, Electric-field-induced pattern formation in layers of DNA molecules at the interface between two immiscible liquids, Physical Review Letters 124 (2020), 064501. SAWs are acoustic waves travelling along the interface between a solid and a fluid. Electroosmotic flow (EOF) induced by surface acoustic waves. In: Physics of Fluids, (2), 32. A sphere moving in the vicinity of a wall experiences an increased fluid-dynamic drag force compared to motion far from solid boundaries, influencing the adsorption of particles at surfaces. 82-85, Proc. Reuse & Permissions. Together with cooperation partners from the Technion/Israel, we have studied the electroosmotic flow along superhydrophobic surfaces, augmented by gate electrodes. Now imaging shrinking the diameter of the wine glass to one millimeter. Unsere Forschung erstreckt sich über ein breites Themenspektrum und kombiniert experimentelle, theoretische und numerische Ansätze. Welcome to the Institute for Nano- und Microfluidics. A summary of the main results can be found here. Administrative Staff Corinna Neumann. If, however, small particles or surfactants are adsorbed to a gas-liquid or liquid-liquid interface, the interface itself becomes viscous. Artificial intelligence is one of the most rapidly advancing and controversial topics in scientific research. We have recently derived analytical expressions for the viscosity coefficients of a particle-laden fluid interface in the limit of low particle concentrations. Usually, viscosity is a quantity associated with the bulk of a fluid. Zu unseren Arbeitsgebieten gehören Gaskinetik auf der Nanoskala, Elektrokinetik, Grenzflächenströmungen, Benetzungsphänomene und Trennprozesse für Biomoleküle. Steffen Hardt. Enhancement of electroosmotic flow on superhydrophobic surfaces. We have studied this phenomenon based on experiments and theory. Reference: M. Shojaeian and S. Hardt, Mass transfer via femtoliter droplets in ping-pong mode, Physical Review Applied 13 (2020), 014015. S. Dehe, B. Rofman, M. Bercovici, and S. Hardt, Electro-osmotic flow enhancement over superhydrophobic surfaces, Physical Review Fluids 5 (2020), 053701. Journal of Fluid Mechanics 883, 47 (2020). Cited by. Knudsen pumps rely on gas-flows induced by temperature differences. Hide All. For a small particle inside a gas, the fluid dynamics of such problems becomes very involved, since the Navier-Stokes equation is no longer applicable. A sphere moving in the vicinity of a wall experiences an increased fluid-dynamic drag force compared to motion far from solid boundaries, influencing the adsorption of particles at surfaces. Vol. L2|06 112. The droplet reciprocates between two aqueous reservoirs under the influence of a DC electric field. Knudsen pumps rely on gas-flows induced by temperature differences. hampe@tvt.tu-... work +49 6151 16-22520. We have studied the transfer of chemical species between the two reservoirs mediated by the droplet. Sort by citations Sort by year Sort by title. Mikrosystemtechnik Kongress 2011, Darmstadt, Germany, [Conference or Workshop Item] Hahn, T. (2011): Interfacial electrokinetic transport phenomena and their impact on DNA electrophoresis in microfluidics. … Duval CNRS Research Director - LIEC Laboratory (Nancy, France) Verified email at univ-lorraine.fr. DNA molecules can be concentrated by electrophoretic accumulation at an interface between two immiscible polymer solutions. Principal institution: Technical University of Darmstadt (TU Darmstadt) Region: Global Subject/journal group: All The table to the right includes counts of all research outputs for Institute for Nano- and Microfluidics (NMF), TU Darmstadt published between 1 October 2019 - 30 September 2020 which are tracked by the Nature Index. Picture: NMF. Anal. Reference: C. Lv, S. N. Varanakkottu, and S. Hardt, Liquid plug formation from heated binary mixtures in capillary tubes, Journal of Fluid Mechanics 889 (2020), A15. “Tears of wine” is a phenomenon that can be observed in wine glasses: Driven by Marangoni stresses, a liquid film crawls up along the glass wall. These results could significantly simplify simulations of two-phase flows with particle-laden interfaces.