Pillar Surfaces Research Articles

Binary imidazolium based aqueous ionic liquid droplet on a rough surface: a molecular dynamics study

Ionic liquids (ILs) have garnered immense attention due to their tunable physicochemical properties. In this study, we delve into the wetting behaviour and interfacial properties of aqueous binary IL mixtures containing [EMIM] [BF4] and [HMIM] [BF4] on both smooth and rough graphite surfaces. Employing classical molecular dynamics simulations, we systematically explored the effects of IL concentration and surface morphology on wetting phenomena. To ensure the equilibrium of the systems, we began by calculating the interaction energies between the components. Subsequently, contact angles were computed, shedding light on the wetting characteristics of the aqueous binary IL mixtures. We meticulously examined the density profiles of the IL systems from the substrate to unravel the dominance of one IL over the other, exploiting the hydrophilic nature of [EMIM] [BF4] and the hydrophobic nature of [HMIM] [BF4]. A comprehensive analysis of hydrogen bond distribution allowed us to discern the intricate nature of these aqueous binary IL droplets. We probed the changes in intermolecular forces within the aqueous IL solution by investigating surface tensions. The tunability of these ILs emerges as a significant aspect of our study, paving the way for their tailored application in engineering and scientific domains. Schematic diagram showing the density distribution of hydrophilic and hydrophobic ILs ([EMIM] [BF4] and [HMIM] [BF4]) in water and also the hydrogen bond (HB) distribution of anion ([BF4]−) water inside the droplet on a pillared surface with a surface fraction ( f ) of 0.4 and pillar height of H = 4 .

Dynamic response of spherical tanks subjected to the explosion of hydrogen-blended natural gas

Hydrogen is a renewable and clean energy and obtains increasing attention all around the world. Blending hydrogen into natural gas can promote hydrogen development and storage tank farms play an essential role in the storage of hydrogen-blended natural gas (HBNG). However, upon leakage from the tank, HBNG accumulates to create a vapor cloud and may explode, resulting in more severe consequences than natural gas. Furthermore, the explosion has the potential to trigger the domino effect in the spherical tank storage area, leading to multiple explosions. But little attention has been paid on this research issue. This article analyzes the dynamic response of the spherical tank exposed to HBNG explosions. The fluid–structure interaction theory is adopted to establish the whole finite element model. Meanwhile, the advanced Arbitrary Lagrangian-Eulerian (ALE) method can reduce mesh distortion and enhance computational accuracy, and the process of explosion is analyzed through the coupling of the Lagrangian mesh for the structure and the Eulerian mesh for the vapor cloud. Then, the algorithm is employed that couples shell elements with solid elements by utilizing a penalty function. Besides, the dynamic response of the spherical tank and pillar surfaces is analyzed in the trends of effective stress, displacement, velocity, and structural damage under various parameters, evaluating the energy absorbed by the spherical tank and pillar. Accordingly, the equipment damage caused by HBNG explosions considering possible damage caused by secondary explosions can be obtained. Then, the effects of the HBNG explosion chain on equipment are analyzed in tank areas. The dynamic response of structures in the explosion is closely related to the different hydrogen blended ratios, distances, and structural thickness, which significantly impact the effective stress of the spherical tank and pillar. Moreover, the damage caused by the HBNG explosion is more serious for pillars than the spherical tank, making the role of pillars crucial in supporting the spherical tank. The results obtained in this study can be used to support the design and safety operation of HBNG storage areas.

Understanding wetting behaviors on rough PTFE surfaces towards n-octane/water mixture separation by molecular dynamics simulation

The wetting behaviors of pure n-octane and water nanodroplets on rectangular pitted, grooved, and rectangular pillared polytetrafluoroethylene (PTFE) surfaces were examined by molecular dynamics simulation. The results showed that the three rough surfaces could achieve superlipophilicity and near superhydrophobicity by changing the rough morphology of surface. The n-octane droplets always presented the Wenzel state on the rough surfaces, and the water droplets were the Wenzel state, Transition state and Cassie state under different phase area fractions and/or roughness factors. Based on completely opposite wetting properties of the two droplets on the same surface, separation performances of mixture nanodroplets were further studied on the three rough PTFE surfaces. The results showed that the n-octane/water separation efficiency of pillared surface was above 98.4 %, significantly higher than those of pitted and grooved surfaces. The rough PTFE surface with special wettability enabled efficient separation of oil/water mixture. This work is expected to pave the way for the rational design and industrial application of oil/water separation materials.

Molecular dynamics simulation study on the wetting characteristics of carbon dioxide droplets on smooth and rough surfaces

A thorough investigation of the wetting behavior of carbon dioxide (CO2) is crucial for enhancing carbon capture efficiency and improving carbon storage and sequestration processes. This work investigates the wetting characteristics of CO2 droplets on smooth and rough Cu-like surfaces using molecular dynamics simulations. The results indicate that an increase in surface energy causes a linear decrease in the contact angle of CO2 droplets on smooth surfaces. An increase in temperature enhances the wetting tendency of the smooth surface toward CO2 droplets. On CO2-phobic surfaces, CO2 droplets tend to detach from the surface, causing the contact angle to increase. On neutral surfaces, CO2 droplets generally maintain wettability, with contact angles remaining almost unchanged. On CO2-philic surfaces, CO2 droplets rapidly wet and spread to form liquid film layers, causing the contact angle to decrease rapidly. In addition, constructing rough surfaces is beneficial for enhancing the surface CO2-phobic property, but the wettability of CO2 droplets varies slightly on different rough surfaces (cylindrical pillars, square pillars, and grooves), the fluctuation of contact angles of CO2 droplets on the grooved surface is relatively small. For square pillared surfaces, in contrast to smooth surfaces, as the surface energy increases, the CO2-phobic property of CO2-phobic surfaces is enhanced, and neutral surfaces can be transformed into CO2-phobic surfaces, with the CO2-philic property of CO2-philic surfaces enhanced. For CO2-phobic square pillared surfaces (α = 0.08), the wetting morphology and wetting modes of CO2 droplets on the square pillared surface are jointly influenced by both the pillar height and the interpillar spacing. When the interpillar spacing is constant, there exists a critical pillar height that can induce the transition of the wetting mode of CO2 droplets from Wenzel to Cassie state.

NUMERICAL SIMULATION OF DROP SPREADING OVER A PILLARED SURFACE

Understanding drop-level interactions with micron-size pillars over flat textured surfaces is required in applications such as condensation of water vapor from a humid environment. Accordingly, the spreading of water drops with diameters of ~ 45 μm over micro-pillars has been studied. The studied cylindrical pillars had a diameter of 3.2 μm, whereas the height and pitch were varied from 15 to 20 μm and 6 to 9 μm, respectively. The impact velocity was varied from 0.02 to 1.89 m/s. The stability of the equilibrium and the transitions in the Cassie-Wenzel wetting states were examined. Three-dimensional simulations showed that drops rebound in closely spaced pillars. In contrast, for a relatively large pitch, drops may rebound and partially or entirely wet the pillars. These details depended on the impact velocity and pillar height. The structure and mechanism of moving contact lines over a pillared surface during impact was also examined. In the simulations, the spreading details were correctly reproduced when a time-dependent contact angle model was adopted, which took into account the nonlinear contribution of friction as well as hysteresis owing to finite pinning. The presence of pinning sites at the edges of the pillars was found to be a major factor affecting the possibility of rebounding and the resulting spreading rate. The simulations of drop shapes using this approach matched the experimental results reported in the literature.

Machine-Learning Approach in Prediction of the Wettability of a Surface Textured with Microscale Pillars.

Tuning the wettability of a flat surface by introducing an array of microscale pillars finds wide applications, especially in engineering a superhydrophobic surface. The wettability of such a pillared surface is quantified by the contact angle (CA) of a water droplet. It is desired to know the CA prior to construction of pillars, in order to obviate the trial-and-errors in experimenting with many different topographies. Given an accurate theoretical prediction of CA has been elusive, we propose a convolutional neural network (CNN) model of CA for a surface patterned with rectangular or cylindrical pillars. By employing a three-dimensional descriptor of the surface topography, the present CNN model can predict experimental CAs within errors comparable to the uncertainties in measuring CAs.

Molecular Simulation Study on the Wettability of a Surface Texturized with Hierarchical Pillars.

By using molecular dynamics simulation, we investigate the wettability of a surface texturized with a periodic array of hierarchical pillars. By varying the height and spacing of the minor pillars on top of major pillars, we investigate the wetting transition from the Cassie-Baxter (CB) to Wenzel (WZ) states. We uncover the molecular structures and free energies of the transition and meta-stable states existing between the CB and WZ states. The relatively tall and dense minor pillars greatly enhance the hydrophobicity of a pillared surface, in that, the CB-to-WZ transition requires an increased activation energy and the contact angle of a water droplet on such a surface is significantly larger.

Cylindrical droplet of aqueous ionic liquids on smooth and pillared graphite surface: A molecular dynamics study

Liquid-solid interaction is ubiquitous and has many applications, such as condensation, boiling, and lubrication. It is crucial to get insight into the wettability of aqueous ILs on different surface topographies at the nano-scale. Here, we have conducted molecular dynamics (MD) simulation on aqueous 1-Ethyl-3-Methylimidazolium Tetrafluoroborate [EMIM] [BF4], 1-Hexyl-3-Methylimidazolium Tetrafluoroborate [HMIM] [BF4] and 1-Ethyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM] [NTF2] at different concentration (10 and 30 wt%) on a both smooth and pillared graphite surface. The contact angle values are estimated to explore the effect of surface texture on the wettability of the aqueous-IL droplet. We ensured that our simulation attained equilibrium by examining the droplet-substrate interaction. Further, we have calculated the distribution of IL molecules through a density contour and, lastly, hydrogen bond (HB) calculation for both hydrophilic ([EMIM] [BF4]) and hydrophobic ([HMIM] [BF4] and [EMIM] [NTF2]) ILs, has been performed to elucidate the structural relationship of ILs.

Droplet evaporation on pillar structured surface: A 3D lattice Boltzmann numerical study

In this paper, a three-dimensional symmetric lattice Boltzmann (LB) model is built up to investigate evaporation of a sessile droplet on pillar structured surfaces. Parametric effects on droplet evaporation, including pillar structure size, roughness, temperature and wettability, are studied comprehensively, with emphasis on the variations of contact angle, contact radius and velocity of triple-phase contact line (TPCL) as well as heat and mass fluxes during evaporation. Pillar structures are found to induce the droplet to split into spherical cap part and liquid film part, resulting in an evaporation mode different from that on a plain surface. The extent of pinning-depinning is strongly associated with structures when TPCL retracts between pillars. Increasing surface temperature can accelerate evaporation by breaking the constant contact angle (CCA) mode, and increasing surface roughness accelerates evaporation by decreasing the duration of CCA mode. The majority of heat and mass transfer takes place around TPCL. High wettability can facilitate the evaporation of spherical cap due to the meniscus at liquid–vapor interface in the vicinity of pillar top surface. The substrate heat flux directly affected by structure size is higher in the region where pillars are distributed, and the solid–liquid interfacial heat flux varies with the specific interface location within droplet. The total mass flux primarily depends on the TPCL length determined by the droplet evaporation mode. When the droplet evaporates by partial penetration in the Cassie state, the amount of evaporation at liquid–vapor interface between pillars is greater than that above pillars. This paper provides more details and insights for a deep understanding of droplet evaporation on pillar structured surfaces.

Effect of liquid splattering on thermal performance of jets and sprays over plain and pillared surfaces

A comparative study of liquid jet and spray is explored over plain and pillared copper surfaces with coolant flow (water) ranging over 3000 < Re < 10500, and heat fluxes up to the critical heat flux limit. Liquid jets and sprays are hydrodynamically characterized using high-speed videography and the phase-Doppler particle analyzer system. The interaction of liquid jets and sprays with the respective metallic substrates is experimentally investigated and strong liquid splattering is observed over the pillared surfaces at higher coolant flow rates. The resulting splattering mass fraction is measured over a range of coolant flow rates and radial positions of the nozzle. Subsequently, the effect of splattering on heat transfer performance is compared for various heat flux conditions by measuring the steady-state surface temperature. Heat transfer coefficient is found to be a strong function of coolant flow rate, operating heat flux conditions, and splattered mass fraction. Significant differences are not seen in these quantities between the liquid jet and spray for a plain surface. However, spray cooling clearly shows superior heat transfer enhancement over a liquid jet for a pillared surface where the critical heat flux limit is significantly delayed. The apparent advantages of heat transfer performance enhancement with patterning of surfaces are not always guaranteed, and the design consideration must address the coolant interaction with it to ensure a net advantage, which may get diminished due to liquid splattering induced by the interaction of the coolant with the patterned surface.

Indoor temperature, humidity, and microorganisms in traditional and modern houses in Japan

Microorganisms in our living environment may affect human health. Microbial suppression by air cleaners and disinfecting agents may provide protection from pathogenic materials. However, excessive microbial suppression can negatively affect human health; thus, an appropriate level of microbiome control is beneficial. It is not well understood how physical environmental conditions, such as temperature and relative humidity, and human lifestyles and behaviors affect indoor microorganisms. To understand the relationship between physical environmental conditions and microbial communities in the human living environment, we measured temperature and relative humidity and collected microbial samples in modern and traditional Japanese houses. In this study, bacteria and fungi were the target microorganisms. In both houses, the DNA concentration of microorganisms on floor surfaces was high when the average relative humidity of the room was high. The same tendency was observed for the beam and pillar surfaces in the traditional house. Although more careful consideration is needed for some indoor surfaces, such as storage ceilings and air conditioner outlets, seasonal changes in relative humidity and DNA concentrations of microorganisms on indoor surfaces exhibit some correlation.

Through-drop imaging of moving contact lines and contact areas on opaque water-repellent surfaces.

A myriad of natural surfaces such as plant leaves and insect wings can repel water and remain unwetted inspiring scientists and engineers to develop water-repellent surfaces for various applications. Those natural and artificial water-repellent surfaces are typically opaque, containing micro- and nano-roughness, and their wetting properties are determined by the details at the actual liquid-solid interface. However, a generally applicable way to directly observe moving contact lines on opaque water-repellent surfaces is missing. Here, we show that the advancing and receding contact lines and corresponding contact area on micro- and nano-rough water-repellent surfaces can be readily and reproducibly quantified using a transparent droplet probe. Combined with a conventional optical microscope, we quantify the progression of the apparent contact area and apparent contact line irregularity in different types of superhydrophobic silicon nanograss surfaces. Contact angles near 180° can be determined with an uncertainty as low as 0.2°, that a conventional contact angle goniometer cannot distinguish. We also identify the pinning/depinning sequences of a pillared model surface with excellent repeatability and quantify the progression of the apparent contact interface and contact angle of natural plant leaves with irregular surface topography.

Phonon localization and resonance in thermal transport of pillar-based GaAs nanowires

Exploring the possibility of nanostructures to modulate thermal conductivity (TC) contributes to promote a deeper comprehension of phonon diffusion and transport processes with the design of thermally insulated devices with high ZT values, and the GaAs nanowires (NWs) widely used in optoelectronic and microelectronic devices exhibit nondiffusive phonon thermal transport phenomena attributed to size effects, while ignoring the wave effects of phonons. Here, we simulate the TC of pillar-based GaAs NWs using non-equilibrium molecular dynamics and Monte Carlo simulations. The spatial distribution of density of states, temperature and heat flow distribution clouds, phonon participation rate, dispersion curves and phonon transmittance of atoms were calculated to investigate the phonon thermal transport processes in pillar-based NWs. The calculation results show that the pillar-based surface reduce the TC by 16%, the TC of pristine NW increases with axial and equivalent diameter, and the TC of pillar-based NW increases nonlinearly with axial length and increases with radial length. The phonon-surface scattering intensity is enhanced by the perturbation introduced by the pillared surface with a substantial decrease in phonon transmission capacity and a break in long-wavelength phonon transport even annihilated, which leads to surface phonon localization. Nanopillars not only enhance the phonon-surface scattering intensity at low frequencies, but also reconfigure the dispersion curve to reduce the group velocity. A series of flat resonance phonon modes are generated throughout the whole spectrum due to the hybridization between the local resonance phonon modes of the nanopillar and the phonon modes of the substrate NWs, resulting in the phonon modes shifting to lower frequencies. The pillar-based surface induced surface phonon localization and local resonance phenomenon contributes to the modulation of phonon thermal transport in GaAs-based field-effect transistors.

Toward Surfaces with Droplet Impact Robustness and Low Contact Angle Hysteresis

AbstractSuperhydrophobic surfaces show excellent water repellent performance. However, liquid impalement occurs when a droplet impacts on the surface at high velocity. To achieve higher resistance to liquid impalement at the same scale, a dense array of structures or structures with pinning at the structures top are typically used, but they also lead to increased contact angle hysteresis and higher energy dissipation. Changing the structure side wall shape can help to maintain low hysteresis and withstand high impact energy at the same scale. Droplet contact angle, contact angle hysteresis and droplet impact experiments are performed on both conical and cylindrical pillar surfaces. Comparing conical and cylindrical pillar structures with the same pitch and height, it is found that cylindrical pillars exhibit higher critical Weber number but result in larger contact angle hysteresis and larger liquid residue size when above a critical Weber number. A proper design of conical structures can maintain large contact angle, low hysteresis, strong resistance to impalement, higher number of bouncing and smaller liquid residue size. In addition, the critical Weber number for the conical structures in this work is higher than micro‐patterned pillar surfaces at the same pitch range, implying that we improve the anti‐wetting performance further.

Can One Predict a Drop Contact Angle?

AbstractThe study of wetting phenomena is of great interest due to the multifaceted technological applications of hydrophobic and hydrophilic surfaces. The theoretical approaches proposed by Wenzel and later by Cassie and Baxter to describe the behavior of a droplet of water on a rough solid are extensively used and continuously updated to characterize the apparent contact angle of a droplet. However, the equilibrium hypothesis implied in these models means that they are not always predictive of experimental contact angles due to the strong metastabilities typically occurring in the wetting of heterogeneous surfaces. A predictive scheme for contact angles is thus urgently needed both to characterize a surface by contact angle measurements and to design super‐hydrophobic and ‐oleophobic surfaces with the desired properties, for example, contact angle hysteresis. In this work, a combination of Monte Carlo simulation and the string method is employed to calculate the free energy profile of a liquid droplet deposited on a pillared surface. For the analyzed surfaces, it is shown that there is only one minimum of the free energy that corresponds to the superhydrophobic wetting state while the wet state can present multiple minima. Furthermore, when the surface roughness decreases the amount of local minima observed in the free energy profile increases. The presented approach clarifies the origin of contact angle hysteresis providing quantitative tools for understanding and controlling wetting at structured surfaces.

Surfaces with bent micro-polymerized pillars exhibit enhanced heat transfer during subcooled flow boiling

Anisotropic wicking surfaces have attracted the attention of numerous research groups in recent years. Wicking characteristics can be improved by generating unidirectional flow behavior within surfaces composed of micropillars that are bent in the direction of interest. In the present work, we created surfaces composed of bent polymerized pillar arrays with center-to-center spacings of 250 and 500 µm and experimentally investigated boiling heat transfer under subcooled flow conditions (40 K). The test surfaces were chemically coated with a 200-nm-thick hydrophilic layer to evaluate the effects thereof on subcooled flow boiling.Surface anisotropy and the center-to center spacings between neighboring pillars significantly improved surface wickability and boiling heat transfer, compared to surfaces with vertically polymerized pillars. Enhancements of the critical heat flux (17–34%) and the heat transfer coefficient (8–71%) were evident on polymerized pillar surfaces compared to bare polymerized surfaces. The experimental results were validated by theoretically analyzing the relationship between the liquid pinning forces and the polymerized pillar surfaces' configurations to understand better how boiling heat transfer was enhanced on anisotropic wicking surfaces during subcooled flow boiling.

The effect of a novel pillar surface morphology and material composition demonstrates uniform osseointegration

Long-term survival of orthopedic implants requires a strong and compliant interface between the implant and surrounding bone. This paper further explores the in-vivo response to a novel, macro-scale osseointegration surface morphology. In this study, we examine the effects of material composition on osseointegration in relation to the controlled surface geometry. The pillared surface is constructed of discontinuous surface geometry which creates an open space for unencumbered bone migration. In creating an open, macro-scale morphology we have demonstrated a bone migration and integration that is less dependent on the underlying implant material and is substantially driven thru surface geometry.In this in-vivo study an established ovine model was used to examine the effects of implant material composition on bone ingrowth and mechanical performance. Cortical and cancellous sites in the tibia and distal femur were examined at 6 and 12 weeks with μCT, histology, histomorphometry, and mechanical performance. Implant materials tested included PEEK (Evonik, VISTAKEEP®), PEEK HA (Invibio, PEEK-OPTIMA HA Enhanced), Titanium coated PEEK, Titanium (Ti–6Al–4V, Grade 5), and Ultra-High Molecular Weight Polyethylene (UHMWPE). Extensive bone ingrowth was noted in all implant materials at 12 weeks with maturation of the bone within the pillar structure from 6 weeks to 12 weeks. Histology demonstrated little fibrous deposition at the implant interface with no adverse cellular reactions. Histomorphometric review of cortical sites revealed greater than 60% bone ingrowth at 6 weeks increasing to nearly 80% by the 12 week timepoint. Cancellous sites yielded a mean of 30% ingrowth at 6 weeks increasing to 35% by 12 weeks. Pushout testing of cortical site samples demonstrated increase in pushout force between the 6 and 12 week timepoints. Increases were significant in all but the UHMWPE samples. Stiffness likewise increased in all samples between the two times.These results demonstrated the effectiveness of the pillar morphology with full integrating from the surrounding bony tissue regardless of the material.

Switchable shape memory wetting surface based on synergistic regulation of surface chemistry and microstructure

Smart control of surface wettability can be obtained by adjusting surface chemistry or regulating surface microstructure, however, coordinated regulation of the two factors on the same surface is still limited. Here, we report a new shape memory composited film consist of a hierarchical pillared polyurethane surface and shape memory polyurethane-cellulose substrate. Reversible switching among multiple wetting states between superhydrophobicity and superhydrophilicity can be realized by synergistic regulation of surface microstructure based on stretching-recovery shape memory effect and surface chemical composition based on O2 plasma-heating. The mild and excellent water-responsive shape memory ability of substrate enables surface microstructure and corresponding wetting to fix at desirable states without keeping continuous external force or stimuli, which is superior to elastomer substrate, responsive molecule modification, or traditional temperature/light triggered shape memory materials. Given the flexibility and versatility, we show its applications in smart platform for creating gradient wettability and patterned micro-reaction.

In-Vivo response to a novel pillared surface morphology for osseointegration in an ovine model

Primary stability and secondary fixation of orthopedic implants to bony tissues are important for healing and long-term functionality. Load sharing and stress transfer are key requirements of an effective implant/tissue interface. This paper presents a novel, macro-scale osseointegration surface morphology which addresses the implant/tissue interface from both the biologic as well as biomechanical perspective. The surface morphology is a controlled, engineered, open topography manifested as discrete pillars projecting from the implant enabling continuous bone ingrowth.The pillared surface is distinct from other porous surfaces and can be differentiated by the localization of the implant material into discrete pillars enabling a continuous mass of bone to freely and easily interdigitate into the pillared structure. Traditional porous structures distribute the implant material throughout the surface forcing the bone to grow in a discontinuous manner. Creating an open and continuous space or “open porosity” in and around the pillar structure allows the bone to easily interdigitate with the implant surface without encumberment from a continuous porous structure.An in-vivo study, using an established ovine model, was undertaken examining the effects of pillar morphology on bone ingrowth and mechanical performance. Cortical and cancellous sites were evaluated utilizing histology, histomophometry, and mechanical pushout, at 4 and 12 weeks. Robust bone ingrowth occurred for all morphologies as was noted in review of the study results. An increase in volume and maturity of bone was noted between the intermediated and final time points. Histomophometry demonstrated over 40% and 80% new bone occupied the available “ingrowth” area at 12 weeks for cancellous and cortical sites (respectively). Histologic review showed little fibrous tissue ingrowth at the interface with no adverse cellular reactions. Testing of cortical samples demonstrated a significant increase in pushout load between the 4 and 12 week timepoints and a 4–8 fold increase in pushout load as compared to the grit blast control. These results demonstrated the effectiveness of the novel interface for orthopedic applications in an in-vivo ovine model.

Active control of surface profile by magnetic micropillar arrays

Pillar arrays have been extensively used in science and engineering, with major applications at the micro or nano scale, requiring a control technique that can operate in a small, confined area. In this study, an active control method for the surface profile was developed using elastic micropillar arrays with magnetic tips. Single-, double-, and multiple-magnetic pillar arrays were fabricated from poly(dimethylsiloxane) and carbonyl iron particles using a mould prepared by laser drilling. The pillar behaviour was investigated in static and moving magnetic fields. In a static magnetic field, a single pillar is bent, double pillars are attached to a pair, and multiple pillars form pair and line patterns parallel to the magnetic field direction at a field strength of 55 mT and 85 mT, respectively, for a horizontal magnetic field. In a moving magnetic field, the propagating deformation of pillar arrays could successfully transport an 8 mm diameter plastic bead horizontally across the pillared surface at a speed of 4 mm s−1.