Surface Patterning Technique Research Articles

Output Enhancement of a 3D‐Printed Triboelectric Nanogenerator Using Laser Surface 3D Patterning

This study investigates the performance of contact separation and sliding modes of triboelectric Nanogenerators (TENGs) using COMSOL Multiphysics simulation environment. The output performance of a plain surface TENG is compared with square, rectangular, and pyramid‐patterned TENGs. The pyramid pattern emerges as the most efficient geometry, demonstrating a solid output of 95.8 V (Voc) and 0.99 μA (Isc). Advanced 3D printing techniques (3DP) including powder‐based multijet fusion and resin‐based polyjet fusion are utilized to print polyamide 12 (PA12) and VeroClear, respectively. The laser surface patterning technique is used to make precise micropatterns on the surfaces of the VeroClear and PA12 layers, resulting in a consistent and effective surface morphology that enhances the surface area of triboelectric layers, and outperforms traditional approaches of patterning in consistency and efficacy. The validation of simulation results is made where the pyramid pattern is emerged as the most efficient geometry experimentally. Performance is maintained with minimal degradation after 102 cycles, and a 22 μF–63 V capacitor is successfully used to store the generated charge. This study not only sets the path for pre‐experimental analysis using simulation environment but also provides a clear demonstration of advanced manufacturing techniques for printing and patterning 3D‐printed triboelectric materials.

Implementation of high‐performance, freestanding flexible film masks through photosensitive polyimide for arbitrary surface micropatterns creation

AbstractGiven the widespread presence of intricate surfaces, the development of electronics has generated a significant demand for surface patterning techniques capable of creating refined or novel patterns. Nevertheless, present surface patterning techniques suffer from complex processes, limited resolution, stringent conditions, and high manufacturing costs. Herein, we present a novel approach for arbitrary surface micropatterning using photosensitive polyimide (PSPI), enabling the in situ fabrication of electrodes without the need for a pattern‐transferring process. On this basis, we have implemented a high‐performance, freestanding flexible thin‐film mask with high optical transparency that facilitates precise alignment of microelectrode patterns with the target material. It also exhibits exceptional mechanical properties suitable for long‐term use and high‐temperature applications, with a notable glass transition temperature of up to 300°C. The fabricated masks with thicknesses of 5–20 μm are well‐suited for high‐resolution applications, including those requiring sub‐5 μm resolution. Furthermore, the creation of microelectrodes on a variety of surfaces utilizing the fabricated PSPI masks was successfully demonstrated. Our facile method provides a solid foundation for achieving efficient micropatterning for the fabrication of high‐performance flexible electronics on complex surfaces.

Moiré effect enables versatile design of topological defects in nematic liquid crystals

Recent advances in surface-patterning techniques of liquid crystals have enabled the precise creation of topological defects, which promise a variety of emergent applications. However, the manipulation and application of these defects remain limited. Here, we harness the moiré effect to engineer topological defects in patterned nematic liquid crystal cells. Specifically, we combine simulation and experiment to examine a nematic cell confined between two substrates of periodic surface anchoring patterns; by rotating one surface against the other, we observe a rich variety of highly tunable, novel topological defects. These defects are shown to guide the three-dimensional self-assembly of colloids, which can conversely impact defects by preventing the self-annihilation of loop-defects through jamming. Finally, we demonstrate that certain nematic moiré cells can engender arbitrary shapes represented by defect regions. As such, the proposed simple twist method enables the design and tuning of mesoscopic structures in liquid crystals, facilitating applications including defect-directed self-assembly, material transport, micro-reactors, photonic devices, and anti-counterfeiting materials.

Reactive laser interference patterning on titanium and zinc in high pressure CO2

Direct laser interference patterning (DLIP) is a versatile technique for surface patterning that enables formation of micro-nano sized periodic structures on top of the target material. In this study, DLIP in high pressure, supercritical and liquid CO2 by 4-beam DLIP was used to pattern titanium and zinc targets. Field emission scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy was used to characterize the patterned surfaces. Field emission SEM analysis showed presence of ordered uniform donut ring pattern with hollow centers for both titanium and zinc with a period slightly under 3 µm while topographical images from atomic force microscopy revealed donut rings protruding outwards typically around 200 nm from target surface and consisted of a crevice at the center with a depth typically around 300 nm and 250 nm for titanium and zinc target, respectively. Based on X-ray photoelectron spectroscopic analysis, this is the first study to report formation of TiO2, TiC, ZnCO3, and zinc hydroxy carbonate on the pattern by DLIP in supercritical and liquid CO2 for titanium and zinc targets. Pressurized CO2 is demonstrated as a promising environment with mirror-based DLIP system for reactive patterning. Due to the superior transport properties and solvent power of supercritical CO2, the current study opens possibilities for reactive patterning in environments that may not have been previously possible.

UV- and Visible-Light Photopatterning of Molecular Gradients Using the Thiol–yne Click Reaction

The rational design of chemical coatings is used to control surface interactions with small molecules, biomolecules, nanoparticles, and liquids as well as optical and other properties. Specifically, micropatterned surface coatings have been used in a wide variety of applications, including biosensing, cell growth assays, multiplexed biomolecule interaction arrays, and responsive surfaces. Here, a maskless photopatterning process is studied, using the photocatalyzed thiol-yne "click" reaction to create both binary and gradient patterns on thiolated surfaces. Nearly defect-free patterns are produced by first coating glass surfaces with mercaptopropylsilatrane, a silanizing agent that forms smoother self-assembled monolayers than the commonly used 3-mercaptopropyltrimethoxysilane. Photopatterning is then performed using UV (365 nm) or visible (405 nm) light to graft molecules onto the surface in tunable concentrations based on the local exposure. The technique is demonstrated for multiple types of molecular grafts, including fluorescent dyes, poly(ethylene glycol), and biotin, the latter allowing subsequent deposition of biomolecules via biotin-avidin binding. Patterning is demonstrated in water and dimethylformamide, and the process is repeated to combine molecules soluble in different phases. The combination of arbitrary gradient formation, broad applicability, a low defect rate, and fast prototyping thanks to the maskless nature of the process creates a particularly powerful technique for molecular surface patterning that could be used for a wide variety of micropatterned applications.

Construction of porous poly (l-lactic acid) surface via carbon quantum dots-assisted static Breath-Figures method

Focused on the design and construction of surface porous morphology of poly (L-lactic acid) membrane. A bottom-up surface patterning technique, static Breath-Figures method, combined with Pickering emulsion mechanism is regulated to fabricate porous poly (L-lactic acid) membrane surface rapidly and reliably. Carbon quantum dots, synthesized in an environment-respecting route, are used to assist the formation of droplet templates. The dimensions and morphology of surface pores can be controlled in a wide range by simply adjusting the content of carbon quantum dots and polymer solution concentration. The effect of the crystallization ability of the adsorption layer formed at the interface between the polymer solution and the water droplet on the pore dimension is proposed. Furthermore, PLLA can be completely degraded by CQD carboxyl catalysis. In brief, we have successfully manufactured a biocompatible PLLA/CQD membrane with a surface porous microstructure which may be potentially applied in cell culture and cell-related research. Compared to previous literature, this work develops a new one-step template patterning method with dynamic controllability. This work also avoids limitations such as high humidity, flowing airflow, and amphiphilic surfactants compared to traditional Breath-Figure approaches.

Surface patterning techniques for proteins on nano- and micro-systems: a modulated aspect in hierarchical structures.

The surface patterning of protein using fabrication or the external functionalization of structures demonstrates various applications in the biomedical field for bioengineering, biosensing and antifouling. This review article offers an outline of the existing advances in protein patterning technology with a special emphasis on the current physical and physicochemical methods, including stencil patterning, trap- and droplet-based microfluidics, and chemical modification of surfaces via photolithography, microcontact printing and scanning probe nanolithography. Different approaches are applied for the biological studies of recent trends for single-protein patterning technology, such as robotic printing, stencil printing and colloidal lithography, wherein the concepts of physical confinement, electrostatic and capillary forces, as well as dielectrophoretics, are summarised to understand the design approaches. Photochemical alterations with diazirine, nitrobenzyl and aryl azide functional groups for the implication of modified substrates, such as self-assembled monolayers functionalized with amino silanes, organosilanes and alkanethiols on gold surfaces, as well as topographical effects of patterning techniques for protein functionalization and orientation, are discussed. Analytical methods for the evaluation of protein functionality are also mentioned. Regarding their selectivity, protein pattering methods will be readily used to fabricate modified surfaces and target-specific delivery systems for the transportation of macromolecules such as streptavidin, and albumin. Future applications of patterning techniques include high-throughput screening, the evaluation of intracellular interactions, accurate screening and personalized treatments.

Hierarchically Fabricated Amyloid Fibers via Evaporation-Induced Self-Assembly.

Multiscale hierarchical nano- and microstructures of amyloid fibrils are fabricated by evaporation-induced self-assembly combined with topographic surface patterning techniques. The continuous stick-and-slip motion induces uniaxial alignment of amyloid fibrils characterized by high orientational order during the drying process. The optical textures of the resultant amyloid aggregates are directly observed by polarized optical microscopy (POM) and atomic force microscopy (AFM). The resulting fiber structure can be tuned by varying the width of the topographic pattern, e.g., the microchannel width, inducing different separation between the deposited amyloid fibers on the glass substrate. Additionally, amyloid fibrils are decorated with gold nanoparticles to produce conductive microwires showing good conductivity (∼10-3 S/m). The finely controlled deposited amyloid fibers presented here can show a way to use naturally-abundant biomaterials for practical applications such as nanowires and sensors.

Multiscale shape-memory effects in a dynamic polymer network for synchronous changes in color and shape

Chameleons and octopuses can escape predators because of their rapid movements, but, in addition, they can change their skin color in response to external stimuli or threats. To date, various smart materials to achieve shape or color changes have been prepared, and the realization of a single responsive behavior in one material is facile, but the development of multi-responsive materials without inter-response interference is challenging. Herein, we report a facile strategy to prepare materials having both shape and color memory by exploiting the shape-memory effect (SME) of a poly(ε-caprolactone) (PCL)-based dynamic network programmed in specific shapes at both the macroscale and microscale. In detail, we used low-cost commercial recordable compact disks as the initial model of a photonic grating nanostructure and imprinted this on the PCL-based network via nanoimprinting and plastic reconfiguration, enabling both temporary and permanent shaping. Controlled by a single molecular stimulus (that is, the switch), the macroscale and microscale shapes recovered synchronously, and the microscale features are manifested as color changes, which we denote “color memory.” Thus, by utilizing the SME of our PCL-based material, bionic models capable of synchronous changes in color and shape on heating were prepared. In addition, using the surface-patterning technique, shape-memory materials having potential for information encryption and transfer platforms were also prepared. The results of this work will expand the use of shape-memory materials to the field of functional memory materials.

Super-hydrophobic/hydrophilic patterning on three-dimensional objects

As superhydrophobic/superhydrophilic (SHPo/SHPi) patterned surfaces can be applied in various fields such as boiling heat transfer and water harvesting, many techniques for their fabrication have been developed. A patterned surface in nature generally has three-dimensionally curved surfaces, such as those observed in the banana leaf and Namib desert beetle. However, existing patterned surface fabrication technologies have a limitation in that they can be applied only to flat surfaces because they are based on laser and ultraviolet techniques. In this study, we proposed a SHPo/SHPi patterning method that can be applied to the fabrication of three-dimensional objects using aluminum. The novelty of the method is the fact that the surface coated to achieve SHPo properties does not cause a chemical reaction with the surface treatment solution. A patterned surface with a contact angle of < 10° for the SHPi surface and > 160° for the SHPo surface was successfully realized. Furthermore, this method enabled desired patterning even in areas that laser light cannot reach, such as the inner walls of a tube. This study allows the expansion of the application scope of the SHPo/SHPi surface patterning technique toward the fabrication of three-dimensional structures, thereby overcoming the limitation of previous patterned surface fabrication technologies.

Polyethylene-supported nanofiltration membrane with in situ formed surface patterns of millimeter size in resisting fouling

Membrane surface properties play important roles in determining the rate and severity of membrane fouling. This paper reported an innovative nanofiltration (NF) membrane called PENF which had a poly(piperazine-amide) active layer formed on a polyethylene (PE) support layer. The PENF membrane was very attractive in that millimeter-sized surface patterns could be automatically formed by the pressing effect of applied pressure for which permeate spacer acted as the in situ imprinter. This was attributed to the thin and tough PE support layer, which could be easily deformed under the applied pressure for NF applications. The surface-patterned PENF membrane (PENF-P) demonstrated greatly enhanced resistance to organic, inorganic and scaling fouling as well as combined fouling, when compared to either the original PENF membrane or commercial NF membranes like NF270. Without surface patterns, the PENF membrane along with other NF membranes followed a same general rule in resisting membrane fouling; a more hydrophilic NF membrane was generally more resistant to fouling. Membrane integrity breaches caused by surface deformation and patterning were negligible in terms of glucose rejection and water permeability coefficient. The PENF-P membrane could reject glucose by >80% at an applied pressure of 3.5 bar and had a water permeability coefficient of >11 L/m2/h/bar. A continuous running of a small-size spiral-wound element of the membrane (0.85 m2) for over 3000 h confirmed that the PENF membrane had a long-time consistently high performance in terms of water permeation and solute rejection. The innovative PENF membrane and the involved surface patterning technique are expected to have a bright application prospect for water treatment and wastewater reclamation.

Oxygen-Induced 1D to 2D Transformation of On-Surface Organometallic Structures.

While surface-confined Ullmann-type coupling has been widely investigated for its potential to produce π-conjugated polymers with unique properties, the pathway of this reaction in the presence of adsorbed oxygen has yet to be explored. Here, the effect of oxygen adsorption between different steps of the polymerization reaction is studied, revealing an unexpected transformation of the 1D organometallic (OM) chains to 2D OM networks by annealing, rather than the 1D polymer obtained on pristine surfaces. Characterization by scanning tunneling microscopy and X-ray photoelectron spectroscopy indicates that the networks consist of OM segments stabilized by chemisorbed oxygen at the vertices of the segments, as supported by density functional theory calculations. Hexagonal 2D OM networks with different sizes on Cu(111) can be created using precursors with different length, either 4,4″-dibromo-p-terphenyl or 1,4-dibromobenzene (dBB), and square networks are obtained from dBB on Cu(100). The control over size and symmetry illustrates a versatile surface patterning technique, with potential applications in confined reactions and host-guest chemistry.

Enhanced Protein Crystallization on Nafion Membranes Modified by Low-Cost Surface Patterning Techniques

In this work, the influence of surface topography on protein crystallization over Nafion® is investigated. Two types of Nafion® based membranes were modified by soft lithographic techniques in orde...

Shaping Metallic Nanolattices: Design by Microcontact Printing from Wrinkled Stamps.

A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.

Height patterning of nanostructured surfaces with a focused helium ion beam: a precise and gentle non-sputtering method

This work presents a new technique for surface patterning with focused ion beams. The technique is based on chemical decomposition in the bulk of a polymer substrate with negligible surface sputtering effects. By using a focused helium ion beam, generated in a helium ion microscope, we show that the surface height of polymethyl methacrylate substrates can be patterned with nanometer depth precision, while preserving the essential features of the nanostructures prefabricated on this surface. The key factors that control this patterning process are discussed.

Scalable macroscale wettability patterns for pool boiling heat transfer enhancement

Boiling utilizes latent heat of vaporization of the fluid to dissipate large amount of heat at small temperature budgets. Surfaces with micro−/nano-scale wettability patterns have been shown to improve the heat transfer coefficient during pool boiling. In this work, we propose a simple and cost-effective technique to fabricate heterogenous surfaces with macroscale wettability patterns comparable to the capillary length of the boiling fluid. We demonstrate that such surfaces can enhance boiling heat transfer coefficient significantly. Four configurations (two samples of hydrophobic dots and lines each) of heterogeneous surfaces are investigated to understand the influence of the diameter, pitch and arrangement of hydrophobic regions on the hydrophilic background surface on the heat transfer coefficient. Results indicate that up to ≈66% enhancement in the heat transfer coefficient can be achieved in comparison to the bare surface. If the hydrophobic dots are spaced out sufficiently, number of dots on the surface controls the heat transfer coefficient at low heat fluxes. However, nucleation is initiated even on the hydrophilic background surface at high heat fluxes and smaller diameter dots start performing better than the larger diameter dots. Smaller pitch (< bubble departure diameter) leads to lateral coalescence among the departing bubbles in case of lined pattern configuration, thereby lowering the heat transfer coefficient. The study demonstrates that simple and cost-effective macroscale wettability patterns can separate liquid supply and vapor removal pathways to enable comparable heat transfer coefficients enhancements otherwise achieved through sophisticated and costly surface patterning techniques discussed in literature.

Superparamagnetic Fe3O4-Au Core-Shell Nanoplasmonic Sensing Array for Label-Free Multiplex Cytokine Detection

The ongoing revolution in fundamental biology and clinical discovery critically hinges on the availability of diagnostic tools capable of decentralized point-of-care measurements to provide immediate quantitative information at the bedside or in the clinic. The case of immune monitoring for practical medical treatment, fast, accurate and high throughput analysis of multiple cytokines using a small sample volume is highly required to precisely determine the rapidly changing immune status of patients in different inflammatory disease conditions. The current “gold standard” clinical technology is mainly based on Enzyme-linked immunosorbent assay (ELISA). The complex labelling and washing processes require a total assay time up to more than 72 hours and a sample volume of 0.5- 2 mL per test per patient, which greatly hinders its application for immune monitoring at the point of care. Label-free optical biosensing platforms, where the optical responses are measured at real-time without the need for secondary labelling, offer unique advantages in rapid analysis of complex biological samples. Among these techniques, inclusive of photonic crystal, optical ring resonator, surface plasmon resonance (SPR), fiber optics and interferometry, the nanoplasmonic biosensing based on the localized surface plasmon resonance (LSPR) of noble metal nanoparticles (NPs) has shown exquisite levels of sensing performance. Recent advances in nanomaterials and nanotechnology have spurred the design and fabrication of next generation nanoplasmonic biosensors with various nanostructures, such as nanorod, nano-bipyramid, nano-flower, nano core-shell structure and nanohole arrays. The nanoplasmonic structures offer remarkable potential in sensor sensitivity, tunability, miniaturization, high throughput capability, and large-scale fabrication. The integration of these platforms into highly functional microfluidic devices has provided novel biological interfacing opportunities and promising features for practical biomarker detection. However, the implementation of such devices for real clinical and pharmaceutical settings has still been prohibited due to the deficiency in throughput and manufacturability without necessarily compromising the desirable sensitivity, multiplicity and reliability. Various microarray nanoplasmonic sensing platforms are flourishing owing to the rapid technology evolution in nanofabrication. They hold great promise in massively parallel quantification of multiple analytes by immobilizing specific antibodies in separate spots on a single array. The versatility of parallel detection has significantly increased the throughput of the nanoplasmonic biosensors for multiplex label-free analysis. Yet, majority of these sensing arrays were fabricated using electron beam lithography, direct laser writing, chemical electrodeposition and dip pen nanolithography, which often require dedicated instrumentations, labor intensive fabrication procedures and are extremely costly for large scale production. While there are a few multi-analyte high-throughput nanoplasmonic sensing platforms being developed at a fast pace, it has become clear that the cost, operation complexity, sensing performance, throughput and scalability are equally challenging issues that must be addressed before the technology can be widely accepted in medical practice. Here, we developed a high-throughput, label-free, multiplex LSPR immunoassay based on a facile magnet assisted fabrication method for Fe3O4/Au core-shell nanoparticles (FACSNPs) microarrays. By harnessing the unique superparamagnetic property of the hollow iron oxide nanocore, we demonstrated an easy-to-implement, scalable nanoparticle surface patterning technique for generating regular-shape, well dispersed, individual sensing spots over a large area. Moreover, the strong plasmonic coupling afforded by the decorated gold nanoparticles (AuNPs) on the FACSNPs exhibit superior sensitivity to the local refractive index change upon cytokine binding. Incorporating our previous developed LSPR dark-field imaging technique, the FACSNPs microarray biosensors can conduct 384 of test on four different cytokines for each sample with 16 replicates per cytokine-test. The integration of the FACSNPs microarray sensors into a simple optofluidic device allows real-time, massively parallel detection of multiple cytokines with a low limit of detection to ~ 20 pg/mL using 1 mL of real biological samples. The stability, accuracy and reproducibility of the immunoassay are further confirmed by standard ELISA and validated through successful demonstration of its practical use for functional immunophenotyping of tumor-associated macrophage (TAM) differentiation. Using the physical and chemical properties of the FACSNPs that arise from both the intrinsic properties of constituent nanoparticles and their interparticle interactions, we adopted a magnet assisted self-assembly process to pattern uniform antibody functioned microarray on a glass substrate. Following the microarray patterning, we functionalized the FACSNPs with a panel of four cytokine antibodies using parallel microfluidic channels. The functioned FACSNPs were imaged under SEM showing a thick layer of antibody coating on the NPs. The successful antibody function yielded four physically separated sensing regions with each consisting of large numbers of microarray sensors targeting specific cytokines. This permits the multiplex detection of four cytokines in a massively parallel manner with high statistic accuracy. Figure 1

Structural Effect of 10um Depth Surface Relief on the Cycling Behavior of Lithium Metal Anode

Lithium metal anodes (LMAs) are required to fulfill higher energy density battery system beyond lithium ion batteries (LIBs). However, practical application of LMAs has been hindered from poor cycle life and safety issue caused by lithium (Li) dendrite growth and inhomogeneous Li plating/stripping. Recently, the Li surface patterning technique was developed for the lower surface current density and stable Li plating/stripping for LMB. Nevertheless, the impact of various factors such as the pattern morphology and charge-discharge condition on Li anode was much unexplored. Here, we report the comparison of the cycling behavior of 10 μm depth continuous and discontinuous surface relief on lithium anode under the Li overflow conditon with varying induced current density. Both continuous and discontinuous surface relief efficiently reduced dendritic Li growth and improved Li plating/stripping behavior than the bare Li anode. The most controlled Li plating/stripping was observed along the discontinuous surface relief. This result affects the improved cycle performance and lowered overpotential of surface patterned lithium metal anode. Furthermore, it was revealed that the 10 μm depth surface relief can not only be applied on the thin (20 μm) Li anode but also enhance cycling stability.

Ripple Formation during Oblique Angle Etching

Chemical removal of materials from the surface is a fundamental step in micro- and nano-fabrication processes. In conventional plasma etching, etchant molecules are non-directional and perform a uniform etching over the surface. However, using a highly directional obliquely incident beam of etching agent, it can be possible to engineer surfaces in the micro- or nano- scales. Surfaces can be patterned with periodic morphologies like ripples and mounds by controlling parameters including the incidence angle with the surface and sticking coefficient of etching particles. In this study, the dynamic evolution of a rippled morphology has been investigated during oblique angle etching (OAE) using Monte Carlo simulations. Fourier space and roughness analysis were performed on the resulting simulated surfaces. The ripple formation was observed to originate from re-emission and shadowing effects during OAE. Our results show that the ripple wavelength and root-mean-square roughness evolved at a more stable rate with accompanying quasi-periodic ripple formation at higher etching angles (θ &gt; 60°) and at sticking coefficient values (Sc) 0.5 ≤ Sc ≤ 1. On the other hand, smaller etching angle (θ &lt; 60°) and lower sticking coefficient values lead to a rapid formation of wider and deeper ripples. This result of this study can be helpful to develop new surface patterning techniques by etching.

Buckling of metallic glass supercooled liquid layer during embossing

Embossing of metallic glass supercooled liquids into templates is emerging as a precision net-shaping and surface patterning technique for metals. Here, we report the effect of thickness of metallic glass on template-based embossing. The results show that the existing embossing theory developed for thick samples fails to describe the process when the thickness of metallic glass becomes comparable to the template cavity diameter. The increased flow resistance at the cavity entrance results in viscous buckling of supercooled liquid instead of filling. A phenomenological equation is proposed to describe the thickness dependent filling of template cavities. The buckling phenomenon is analyzed based on the folding model of multilayer viscous media. We show that controlled buckling can be harnessed in the fabrication of metal microtubes, which are desirable for many emerging applications.