Thomas Michael Schutzius

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Schutzius

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Thomas Michael

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0000-0003-3309-3568

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Publications 1 - 10 of 17

Imparting scalephobicity with rational microtexturing of soft materials
Schmid, Julian; Armstrong, Tobias; Dickhardt, Fabian J.; et al. (2023)
Science Advances
Crystallization fouling, a process where scale forms on surfaces, is widespread in nature and technology, negatively affecting energy and water industries. Despite the effort, rationally designed surfaces that are intrinsically resistant to it remain elusive, due in part to a lack of understanding of how microfoulants deposit and adhere in dynamic aqueous environments. Here, we show that rational tuning of coating compliance and wettability works synergistically with microtexture to enhance microfoulant repellency, characterized by low adhesion and high removal efficiency of numerous individual microparticles and tenacious crystallites in a flowing water environment. We study the microfoulant interfacial dynamics in situ using a micro-scanning fluid dynamic gauge system, elucidate the removal mechanisms, and rationalize the behavior with a shear adhesive moment model. We then demonstrate a rationally developed coating that can remove 98% of deposits under shear flow conditions, 66% better than rigid substrates.
The Fluid Diode: Tunable Unidirectional Flow through Porous Substrates
Mates, Joseph E.; Schutzius, Thomas Michael; Qin, Jian; et al. (2014)
ACS Applied Materials & Interfaces
Many important applications in fluid management could benefit from unidirectional transport through porous media via a simple, large-area, low-cost coating treatment; in essence, a fluid diode demonstrated herein for water using common cellulosic paper substrates. In electronics, the diode is an electrical component with asymmetric current transfer characteristics. A light (<2 g/m2) superhydrophobic conformal coating applied onto one side of a porous substrate is shown to create a liquid transport function analogous to the electronic diode, facilitating fluid movement in one direction under negligible penetration pressures, but opposing it in reverse up to greater pressures. The phenomenon is driven by capillary action and can be observed using any similarly-thin fluid barrier applied on only one side (i.e., wettability contrast) of an absorbent porous matrix. Diodic action and liquid transport rates are shown to be highly tunable, determined by fiber diameter and spacing, in combination with coating deposition amount. As an example, the device is used to separate an oil/water mixture, relying upon the surface tension differences of the mixture constituents, and may be implemented in multicomponent fluid filtration/separation technologies.
The effect of additives on water vapor condensation on bituminous surfaces
Tarpoudi Baheri, Farrokh; Rico Luengo, Miguel; Schutzius, Thomas Michael; et al. (2022)
Journal of Testing and Evaluation
Water condensation and freezing on asphalt roads can lead to slippery conditions, which are responsible for many winter accidents and have caused an overreliance on mostly environmentally damaging and pavement degrading deicing chemicals and salt, which requires active maintenance. Bitumen is a mechanically and chemically complex material mainly consisting of various hydrocarbon-based chemicals groups. Additionally, bitumen makes up approximately 5 wt.% of the asphalt concrete mixture because of its binder role and coating function of the aggregates, can control the bulk mechanical properties and surface properties of the asphalt mixture. Condensation as the first step and later freezing phenomena are investigated in this study and from ambient humidity toward understanding the fundamentals of icing on bituminous surfaces. Condensation experimental results show selective wettability of chemically and mechanically district bitumen surface domains. The effect of different bitumen modifiers of polyethylene terephthalate, polyamide (PA 66), polyacrylonitrile, and Sasobit wax at 1 wt.% were studied on condensation freezing and bitumen water affinity.
Bistability of Dielectrically Anisotropic Nematic Crystals and the Adaptation of Endothelial Collectives to Stress Fields
Stefopoulos, Georgios; Lendenmann, Tobias; Schutzius, Thomas Michael; et al. (2022)
Advanced Science
Endothelial monolayers physiologically adapt to flow and flow-induced wall shear stress, attaining ordered configurations in which elongation, orientation, and polarization are coherently organized over many cells. Here, with the flow direction unchanged, a peculiar bi-stable (along the flow direction or perpendicular to it) cell alignment is observed, emerging as a function of the flow intensity alone, while cell polarization is purely instructed by flow directionality. Driven by the experimental findings, the parallelism between endothelia is delineated under a flow field and the transition of dual-frequency nematic liquid crystals under an external oscillatory electric field. The resulting physical model reproduces the two stable configurations and the energy landscape of the corresponding system transitions. In addition, it reveals the existence of a disordered, metastable state emerging upon system perturbation. This intermediate state, experimentally demonstrated in endothelial monolayers, is shown to expose the cellular system to a weakening of cell-to-cell junctions to the detriment of the monolayer integrity. The flow-adaptation of monolayers composed of healthy and senescent endothelia is successfully predicted by the model with adjustable nematic parameters. These results may help to understand the maladaptive response of in vivo endothelial tissues to disturbed hemodynamics and the progressive functional decay of senescent endothelia.
Microscale investigation on interfacial slippage and detachment of ice from soft materials
Regulagadda, Kartik; Gerber, Julia; Schutzius, Thomas Michael; et al. (2022)
Materials Horizons
Surface icing is detrimental to applications ranging from transportation to biological systems. Soft elastomeric coatings can engender remarkably low ice adhesion strength, but mechanisms at the microscale and resulting ice extraction outcomes need to be understood. Here we investigate dynamic ice-elastomer interfacial events and show that the ice adhesion strength can actually vary by orders of magnitude due to the shear velocity. We study the detailed deformation fields of the elastomer using confocal traction force microscopy and elucidate the underlying mechanism. The elastomer initially undergoes elastic deformation having a shear velocity dependent threshold, followed by partial relaxation at the onset of slip, where velocity dependent "stick-slip" micropulsations are observed. The results of the work provide important information for the design of soft surfaces with respect to removal of ice, and utility to fields exemplified by adhesion, contact mechanics, and biofouling.
Leidenfrost droplet trampolining
Graeber, Gustav; Regulagadda, Kartik; Hodel, Pascal; et al. (2021)
Nature Communications
A liquid droplet dispensed over a sufficiently hot surface does not make contact but instead hovers on a cushion of its own self-generated vapor. Since its discovery in 1756, this so-called Leidenfrost effect has been intensively studied. Here we report a remarkable self-propulsion mechanism of Leidenfrost droplets against gravity, that we term Leidenfrost droplet trampolining. Leidenfrost droplets gently deposited on fully rigid surfaces experience self-induced spontaneous oscillations and start to gradually bounce from an initial resting altitude to increasing heights, thereby violating the traditionally accepted Leidenfrost equilibrium. We found that the continuously draining vapor cushion initiates and fuels Leidenfrost trampolining by inducing ripples on the droplet bottom surface, which translate into pressure oscillations and induce self-sustained periodic vertical droplet bouncing over a broad range of experimental conditions.
Patterning of colloidal droplet deposits on soft materials
Gerber, Julia; Schutzius, Thomas Michael; Poulikakos, Dimos (2021)
Journal of Fluid Mechanics
The ‘coffee stain ring’ is a particle deposit, that forms naturally, when the liquid of a suspension drop evaporates, leaving the particles at the edge of the deposit. Although observed in coffee cups in everyday life, such deposits appear in a wide range of liquid, particle and surface combinations and have attracted vivid research attention. Previous studies focused on the fluidics of evaporating suspension droplets on rigid materials, where the ring formation was shown to occur for pinned contact lines, and possible suppression of the coffee stain effect with surfactants, or other externally driven means, was investigated. Here, we show that, on soft materials, we can control the topography of the deposit on demand – promoting or suppressing the coffee ring effect – by simply changing the environmental humidity, regulating the evaporative flux. We perform particle tracking of droplets drying on soft substrates at varied environmental conditions and show with experimental observations and theoretical analysis that, at an expedited contact line velocity, particles are advected towards the receding contact line. We relate this advection to the viscous dissipation within the soft solid, retarding the contact line motion. The coffee ring formation in the presence of a receding contact line and its control by the environmental humidity, bring a new perspective to the conditions of the manifestation of this frequent deposit topography. We demonstrate the importance of our findings during the printing of a colloidal line, showing the ability to trigger line bifurcation on soft substrates by regulating the evaporative flux, introducing another degree of controllability for contact printing.
Nanostructured Surfaces Enhance Nucleation Rate of Calcium Carbonate
Armstrong, Tobias; Schmid, Julian; Niemelä, Janne-Petteri; et al. (2024)
Small
Nucleation and growth of calcium carbonate on surfaces is of broad importance in nature and technology, being essential to the calcification of organisms, while negatively impacting energy conversion through crystallization fouling, also called scale formation. Previous work studied how confinements, surface energies, and functionalizations affect nucleation and polymorph formation, with surface-water interactions and ion mobility playing important roles. However, the influence of surface nanostructures with nanocurvature-through pit and bump morphologies-on scale formation is unknown, limiting the development of scalephobic surfaces. Here, it is shown that nanoengineered surfaces enhance the nucleation rate by orders of magnitude, despite expected inhibition through effects like induced lattice strain through surface nanocurvature. Interfacial and holographic microscopy is used to quantify crystallite growth and find that nanoengineered interfaces experience slower individual growth rates while collectively the surface has 18% more deposited mass. Reconstructions through nanoscale cross-section imaging of surfaces coupled with classical nucleation theory-utilizing local nanocurvature effects-show the collective enhancement of nano-pits.
Exploiting radiative cooling for uninterrupted 24-hour water harvesting from the atmosphere
Haechler, Iwan; Park, Hyunchul; Schnoering, Gabriel; et al. (2021)
Science Advances
Atmospheric water vapor is ubiquitous and represents a promising alternative to address global clean water scarcity. Sustainably harvesting this resource requires energy neutrality, continuous production, and facility of use. However, fully passive and uninterrupted 24-hour atmospheric water harvesting remains a challenge. Here, we demonstrate a rationally designed system that synergistically combines radiative shielding and cooling— dissipating the latent heat of condensation radiatively to outer space—with a fully passive superhydrophobic condensate harvester, working with a coalescence-induced water removal mechanism. A rationally designed shield, accounting for the atmospheric radiative heat, facilitates daytime atmospheric water harvesting under solar irradiation at realistic levels of relative humidity. The remarkable cooling power enhancement enables dew mass fluxes up to 50 g m−2 hour−1, close to the ultimate capabilities of such systems. Our results demonstrate that the yield of related technologies can be at least doubled, while cooling and collection remain passive, thereby substantially advancing the state of the art.
Omnidirectional droplet propulsion on surfaces with a Pac-Man coalescence mechanism
Chaaban, Jana; Galliker, Patrick; Schutzius, Thomas Michael; et al. (2020)
Physical Review Fluids
Dispensing, transporting, and manipulating minute liquid volumes is important to a wide range of scientific and application areas, spanning from biology and medicine to chemistry and materials. Although digital microfluidics are emerging as a popular methodology in the lab-on-a-chip field, important obstacles to its broad adoption, such as those related to reusability, reconfigurability, and susceptibility to fouling, persist. In addition, as liquid volumes decrease in size, their sustenance in an open atmosphere becomes practically impossible due to high volatility, leading rapidly to complete evaporation. Here we introduce and demonstrate a microfluidic platform based on the coalescence-induced self-propulsion of sessile microdroplets on unpatterned substrates. We employ controlled dropwise liquid ejection by electrohydrodynamic printing to create, actively sustain (despite high volatility), and freely translate femtoliter-sized droplets (∼2–5 μm radius) under open-atmosphere conditions. The omnidirectional planar movement of the droplets is achieved by a precisely controlled, on-demand sequence of coalescence events, where the directed motion of an already deposited droplet is dictated by the positioning of the subsequent droplet printed adjacent to it. We studied the transport mechanism experimentally and theoretically and found that, for short time scales (relative to the substrate translation and droplet evaporation), the radial growth of the new smaller droplet being printed can greatly exceed the retraction of the neighboring, already deposited droplet. This rapid growth is exploited to create a liquid meniscus bridging the so generated droplet doublet, and merging it into a single droplet by the action of capillary pressure differences. Evaporative losses ensure that the moving droplets are kept at a constant size after merging, in each coalescence cycle. We observe this coalescence whenever the interspacing between two sequentially printed droplets is below a critical value, and show that we can control this with the underlying substrate velocity. Armed with this transport mechanism, we then demonstrate the utility of this approach by tasking the coalescing self-propelled droplet doublet to perform microfluidic operations such as collecting, transporting, and merging solid residues on a surface, in an on-demand, Pac-Man type motion, exemplifying capabilities for digital microfluidic applications.

Publications 1 - 10 of 17

Thomas Michael Schutzius

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