hardt@nmf.tu-... +49 6151 16-24274. In that case, ring-like structures are formed from the film. Reuse & Permissions. DOI: 10.1103/PhysRevApplied.13.014015. SAWs are acoustic waves travelling along the interface between a solid and a fluid. Nanoscale gas kinetics, electrokinetics, interfacial flows, wetting phenomena and biomolecular separation belong to our areas of work. Transferring chemical species or nanoparticles in a controlled way becomes challenging when very small species amounts are considered. The transition from the Cassie state to these intermediate states is partially reversible. TU Darmstadt incorporates diverse science cultures to create its characteristic profile. We have studied the transport of gas mixtures along a Knudsen pump and observed differences in flow of the individual components of the mixture. 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. Head of Institute. We have studied this phenomenon based on experiments and theory. Artificial intelligence is one of the most rapidly advancing and controversial topics in scientific research. Therefore, SAW-induced EOF may be useful as a method for pumping liquids through small scale channels. S. Dehe, B. Rofman, M. Bercovici, and S. Hardt, Electro-osmotic flow enhancement over superhydrophobic surfaces, Physical Review Fluids 5 (2020), 053701. These results could significantly simplify simulations of two-phase flows with particle-laden interfaces. 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. 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. 5, Iss. Our research extends over a broad thematic spectrum and combines experimental, theoretical and numerical approaches. Dr. Dharmendra Tripathi Associate Professor, Mathematics, National Institute of Technology Uttarakhand Verified email at nituk.ac.in. Together with cooperation partners from the Technion/Israel, we have studied the electroosmotic flow along superhydrophobic surfaces, augmented by gate electrodes. † Email address for correspondence: hardt@nmf.tu-darmstadt.de. A summary of the main results can be found here. In that case, the viscosity coefficients represent the dissipation due to the presence of particles or surfactants in an average manner. 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. Surface acoustic waves (SAW) are widely used in microfluidics for transporting and mixing liquids. Welcome to the Institute for Nano- und Microfluidics. 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. 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. 6 — June 2019. As a stream encounters an obstacle, floating debris sometimes piles up in front of the obstacle, forming a dense layer on the water surface. Issue. A summary of the main results can be found here. We find a multitude of intermediate states between the classical Cassie and Wenzel states. A: Alarich-Weiss-Straße 10, L2|06 111, 64287 Darmstadt, GER T: +49 6151 16-24276. Cited by. Anal. In addition, the flow is entirely pH-independent. Steffen Hardt Professor, TU Darmstadt Потвърден имейл адрес: nmf.tu-darmstadt.de. Преглед на всички. Please find below older news relating to research at the Institute for Nano- and Microfluidics. Sort. Click here for details, Species transfer using small droplets as carriers. Articles Cited by Co-authors. Intermediate wetting states on superhydrophobic surfaces. Herzlich willkommen am Fachgebiet Nano- und Mikrofluidik. 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. 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. Transferring chemical species or nanoparticles in a controlled way becomes challenging when very small species amounts are considered. Upon touching the reservoir, the droplet reverses its charge and its direction of motion. Hongya Geng UCAS, ICCAS, Tsinghua, ICL Verified email at imperial.ac.uk. References (Subscription Required) Click to Expand. TU Darmstadt; Maschinenbau; Nano- und Mikrofluidik; Personal; Mitarbeiterinnen und … Enhancement of electroosmotic flow on superhydrophobic surfaces. Therefore, SAW-induced EOF may be useful as a method for pumping liquids through small scale channels. Institute for Nano- and Microfluidics. Vol. 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. Please find below all contacts to board, project coordinators, researchers, administrative and technical staff of the CRC 1194. Research; Relationships; 1 August 2019 - 31 July 2020. TU Darmstadt; Maschinenbau; Nano- and Microfluidics; Staff; People Name Working area(s) Contact; Director of the institute Prof. Dr. rer. Tobias Baier Center of Smart Interfaces, TU Darmstadt Verified email at nmf.tu-darmstadt.de. … Up to now, the electrokinetic effects due to SAWs have remained largely unexplored. No articles found. Hirofumi Shintaku RIKEN Hakubi Team Leader Verified email at me.kyoto-u.ac.jp. Electroosmotic flow (EOF) induced by surface acoustic waves. The transition from the Cassie state to these intermediate states is partially reversible. Steffen Hardt. We have recently derived analytical expressions for the viscosity coefficients of a particle-laden fluid interface in the limit of low particle concentrations. In: Physics of Fluids, (2), 32. nat. Fachgebiet Nano- und Mikrofluidik – Herzlich willkommen am Fachgebiet Nano- und Mikrofluidik. Return to institution outputs. SAWs are acoustic waves travelling along the interface between a solid and a fluid. 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. 82-85, Proc. We have studied the transport of gas mixtures along a Knudsen pump and observed differences in flow of the individual components of the mixture. B. Rofman, S. Dehe, V. Frumkin, S. Hardt, and M. Bercovici, Intermediate states of wetting on hierarchical superhydrophobic surfaces, Langmuir 36 (2020), 5517−5523. The droplet reciprocates between two aqueous reservoirs under the influence of a DC electric field. Therefore, such a pump may be used for gas separation. Steffen Hardt Professor, TU Darmstadt Verified email at nmf.tu-darmstadt.de. We have studied the transfer of chemical species between the two reservoirs mediated by the droplet. We have studied the transfer of chemical species between the two reservoirs mediated by the droplet. 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. 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. Institute for Nano- and Microfluidics, TU Darmstadt, 64287 Darmstadt, Germany * hardt@nmf.tu-darmstadt.de; Article Text (Subscription Required) Click to Expand. Ehsan Ro 1994 Molecular Gas Dynamics and the Direct Simulation of Gas Flows. https://www.fdy.tu-darmstadt.de/fdy/fdystaff/details_17472.de.jsp Institute of Applied Geosciences (IAG), TU Darmstadt . Now imaging shrinking the diameter of the wine glass to one millimeter. Title. Flow and streaming potential of an electrolyte in a channel with an axial temperature gradient - Volume 813 - Mathias Dietzel, Steffen Hardt We have recently derived analytical expressions for the viscosity coefficients of a particle-laden fluid interface in the limit of low particle concentrations. ‡ hardt@nmf.tu-darmstadt.de; Article Text (Subscription Required) Click to Expand. M. Dietzel and S. Hardt, Electroosmotic flow in small-scale channels induced by surface-acoustic waves, Physical Review Fluids 5 (2020), 123702. The theoretical predictions based on linear stability analysis compare favorably with the experimental results. 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. DOI:10.1017/jfm.2019.921. Cited by. The method is sketched in the schematic on the left. Bird, G. A. M. Dietzel and S. Hardt, Electroosmotic flow in small-scale channels induced by surface-acoustic waves, Physical Review Fluids 5 (2020), 123702. Intermediate wetting states on superhydrophobic surfaces. Microfluid Nanofluid 24, 41 (2020). DOI:10.1017/jfm.2019.921. Verified email at nmf.tu-darmstadt.de. In that case, ring-like structures are formed from the film. 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. We investigate the impact of insoluble surfactants on shear flow along a superhydrophobic surface in Cassie state, with gas trapped in grooves oriented perpendicular to the flow direction. We have experimentally studied the concentration patterns and formulated a theory describing the pattern formation. Klingenberg, Dario ; Oberlack, Martin ; Pluemacher, Dominik (2020): Symmetries and turbulence modeling. As a stream encounters an obstacle, floating debris sometimes piles up in front of the obstacle, forming a dense layer on the water surface. 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. Steffen Hardt Professor, TU Darmstadt Verified email at nmf.tu-darmstadt.de. In that context we are especially interested in studying fundamentals, with the intention to pave the way for novel applications. 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. 26 (1), 45 – 65. Seyed Mahmood Mousavi High Performance Computing center (HPCC) Потвърден имейл адрес: shirazu.ac.ir. References (Subscription Required) Click to Expand. 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. 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. 6 Intitut für Angewandte Geowissenschaften, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt, Germany. 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. A summary of the main results can be found here. Below, the same research outputs are grouped by subject. 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. Latest supplement. Download file × 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. Tobias Baier Center of Smart Interfaces, TU Darmstadt Потвърден имейл адрес: nmf.tu-darmstadt.de. Baier, T., Hardt, S. Gas separation in a Knudsen pump inspired by a Crookes radiometer. You are here: TU Darmstadt; Maschinenbau; Nano- and Microfluidics; Home; Institute for Nano- and Microfluidics. Sitemap Picture: NMF. Knudsen pumps rely on gas-flows induced by temperature differences. pp. Nano- and Microfluidics Supplemental Material (Subscription Required) Click to Expand. Office. 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. 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. Mikrosystemtechnik Kongress 2011, Darmstadt, Germany, [Conference or Workshop Item] Hahn, T. (2011): Interfacial electrokinetic transport phenomena and their impact on DNA electrophoresis in microfluidics. 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. https://doi.org/10.1007/s10404-020-02342-6. Steffen Hardt Professor, TU Darmstadt Verified email at nmf.tu-darmstadt.de. Electronic address: stark@pos.tu-darmstadt.de. 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. Nano- and Microfluidics You are here: TU Darmstadt; Maschinenbau; Nano- and Microfluidics; Sitemap. The table to the right includes counts of all research outputs for Technical University of Darmstadt (TU Darmstadt) published between 1 September 2019 - 31 August 2020 which are tracked by the Nature Index. DOI: 10.1017/jfm.2020.80, Pattern formation in layers of DNA molecules. Philippe Davy directeur de recherche, CNRS, Rennes Verified email at univ-rennes1.fr. DNA molecules can be concentrated by electrophoretic accumulation at an interface between two immiscible polymer solutions. 5 — May 2020. References. Duval CNRS Research Director - LIEC Laboratory (Nancy, France) Verified email at univ-lorraine.fr. Baier, T., Hardt, S. Gas separation in a Knudsen pump inspired by a Crookes radiometer. Link: https://doi.org/10.1017/jfm.2019.921. Surface acoustic waves (SAW) are widely used in microfluidics for transporting and mixing liquids. Zu unseren Arbeitsgebieten gehören Gaskinetik auf der Nanoskala, Elektrokinetik, Grenzflächenströmungen, Benetzungsphänomene und Trennprozesse für Biomoleküle. hampe@tvt.tu-... work +49 6151 16-22520. Usually, viscosity is a quantity associated with the bulk of a fluid. Hide All. Usually, viscosity is a quantity associated with the bulk of a fluid. The droplet reciprocates between two aqueous reservoirs under the influence of a DC electric field. In that case, the viscosity coefficients represent the dissipation due to the presence of particles or surfactants in an average manner. Reference: M. Shojaeian and S. Hardt, Mass transfer via femtoliter droplets in ping-pong mode, Physical Review Applied 13 (2020), 014015. References (Subscription Required) Click to Expand. Link: https://doi.org/10.1017/jfm.2019.921. Click here for details, Species transfer using small droplets as carriers. Physical Review B 70 (12), 125111, 2004. S. 025108, ISSN 1070-6631, DOI: 10.1063/1.5141165, [Online-Edition: https://doi.org/10.1063/1.5141165], [Artikel] SIAM J. Numer. The theoretical predictions based on linear stability analysis compare favorably with the experimental results. We have studied this phenomenon based on experiments and theory. Unsere Forschung erstreckt sich über ein breites Themenspektrum und kombiniert experimentelle, theoretische und numerische Ansätze. Vol. ‡ Corresponding author: hardt@nmf.tu-darmstadt.de; Article Text (Subscription Required) Click to Expand. Supplemental Material (Subscription Required) Click to Expand. Institute of Printing Science and Technology, TU Darmstadt did not contribute to any primary research papers from Nature Index journals in the current 12 month window. 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. Issue . Microfluid Nanofluid 24, 41 (2020). “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. Surfactants can immobilize fluid–liquid interfaces under shear stress. Philippe Bourrianne Princeton Verified email at princeton.edu. DNA molecules can be concentrated by electrophoretic accumulation at an interface between two immiscible polymer solutions. If, however, small particles or surfactants are adsorbed to a gas-liquid or liquid-liquid interface, the interface itself becomes viscous. This kind of separation of gas species by mass or size plays an important role for many applications in chemical engineering. DOI: 10.1017/jfm.2020.80, Pattern formation in layers of DNA molecules. Tobias Baier Center of Smart Interfaces, TU Darmstadt Verified email at nmf.tu-darmstadt.de. Jérôme F.L. 4, Iss. We are concerned with transport phenomena in fluids on the nano- and micrometer scale. T Baier, E Bick, C Wetterich. Reuse & Permissions . Upon touching the reservoir, the droplet reverses its charge and its direction of motion. DOI: 10.1103/PhysRevApplied.13.014015. 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. 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. Reference: M. Shojaeian and S. Hardt, Mass transfer via femtoliter droplets in ping-pong mode, Physical Review Applied 13 (2020), 014015. Your browser does not support the video element. About TU Darmstadt – The Technical University (TU) of Darmstadt is one of Germany’s leading technical universities. 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. This kind of separation of gas species by mass or size plays an important role for many applications in chemical engineering. Knudsen pumps rely on gas-flows induced by temperature differences. Therefore, such a pump may be used for gas separation. In addition, the flow is entirely pH-independent. 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. www.nmf.tu-darmstadt.de. 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. Clarendon Press. Up to now, the electrokinetic effects due to SAWs have remained largely unexplored. 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. Zu unseren Arbeitsgebieten gehören Gaskinetik auf der Nanoskala, Elektrokinetik, Grenzflächenströmungen, Benetzungsphänomene und Trennprozesse für Biomoleküle. Electronic address: kleebe@geo.tu-darmstadt.de. S. Dehe, B. Rofman, M. Bercovici, and S. Hardt, Electro-osmotic flow enhancement over superhydrophobic surfaces, Physical Review Fluids 5 (2020), 053701. These results could significantly simplify simulations of two-phase flows with particle-laden interfaces. Babovsky, H. & Illner, R. 1989 A convergence proof for Nanbu’s simulation method for the full Boltzmann equation. 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. Markus Biesalski Professor für Makromolekulare Chemie und Papierchemie, Technische Universität Darmstadt Verified email at cellulose.tu-darmstadt.de. “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. We have experimentally studied the concentration patterns and formulated a theory describing the pattern formation. Human resources department, International office: neumann@nmf.tu-... +49 6151 16-24277. Together with cooperation partners from the Technion/Israel, we have studied the electroosmotic flow along superhydrophobic surfaces, augmented by gate electrodes. A summary of the main results can be found here. ‘Super-hydrophobic’ surfaces with embedded gas pockets have been suggested for reducing drag on objects moving through water. L2|06 113. 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. Electroosmotic flow (EOF) induced by surface acoustic waves. Tobias Baier Center of Smart Interfaces, TU Darmstadt Verified email at nmf.tu-darmstadt.de. Institute for Nano- and Microfluidics (NMF), TU Darmstadt . Nature Index 2020 Artificial Intelligence. Следене. ‘Super-hydrophobic’ surfaces with embedded gas pockets have been suggested for reducing drag on objects moving through water. The course language will be English. L2|06 112. If, however, small particles or surfactants are adsorbed to a gas-liquid or liquid-liquid interface, the interface itself becomes viscous. Weian Sheng Airbnb, Intel, University of Florida Verified email at airbnb.com. We find a multitude of intermediate states between the classical Cassie and Wenzel states. Electronic address: hardt@nmf.tu-darmstadt.de. Dr. Naren Bag PhD, IIT Kharagpur Verified email at iitkgp.ac.in. christophe clanet CNRS, LadHyX, Ecole … Stability and collapse of holes in liquid layers - Volume 855 - Cunjing Lv, Michael Eigenbrod, Steffen Hardt These liquid rings finally collapse and form plugs that are propelled along the capillary tube by evaporation. https://doi.org/10.1007/s10404-020-02342-6. BHANUMAN BARMAN Assistant Professor, NIT Patna Verified email at nitp.ac.in. 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. These liquid rings finally collapse and form plugs that are propelled along the capillary tube by evaporation. Song Jinlong The School of Mechanical Engineering, Dalian University of Technology Verified email at dlut.edu.cn. Administrative Staff Corinna Neumann. Hover over the donut graph to view the FC output for each subject. The method is sketched in the schematic on the left. Contact. Sort by citations Sort by year Sort by title. Enhancement of electroosmotic flow on superhydrophobic surfaces. 7 Physics of Surfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 16, 64287 Darmstadt, Germany. Journal of Fluid Mechanics 883, 47 (2020). 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. Institut für Druckmaschinen und Druckverfahren, TU Darmstadt Germany . B. Rofman, S. Dehe, V. Frumkin, S. Hardt, and M. Bercovici, Intermediate states of wetting on hierarchical superhydrophobic surfaces, Langmuir 36 (2020), 5517−5523. Unsere Forschung erstreckt sich über ein breites Themenspektrum und kombiniert experimentelle, theoretische und numerische Ansätze. Now imaging shrinking the diameter of the wine glass to one millimeter. fluid dynamics microfluidics electrokinetics. Issue. Steffen Hardt Professor, TU Darmstadt Verified email at nmf.tu-darmstadt.de. Year; Temperature dependence of antiferromagnetic order in the Hubbard model. Working area(s) Emeritus. The course language will be English. Journal of Fluid Mechanics 883, 47 (2020).