Introduction

Liquid-based materials are evident in the survival mechanisms of various organisms, e.g., the slippery surfaces of carnivorous plants, optically perfect surfaces of eyes, and adhesive shape-adaptive topologies of insect feet1,2. These natural mechanisms, which often involve porous architectures, have inspired the development of solid–liquid composites. Functional liquids infused into diverse solid materials, such as polymers, gels, ceramics, and metals, have driven the creation of mobile and reconfigurable interfaces, yielding diverse surface behaviors. Biomimetic approaches have allowed the engineering of liquid-infused slippery surfaces that repel diverse substances and have self-healing features3,4. These slippery surfaces have extensive applications in droplet manipulation5,6, antibiofouling7,8,9, deicing10,11, and biosensing12,13. Despite these advances, scalable fabrication of slippery surfaces with structural and interfacial complexity remains challenging. Most liquid-infused surfaces are confined to planar or simply patterned geometries owing to the limitations imposed by fabrication strategies such as spraying14,15, coating16,17,18, infiltration3,19,20,21, gelation22,23, template-guided approaches24, and photolithographic methods25,26,27. Among these, photolithography-based approaches enable high-resolution patterning and precise lubricant infusion. However, they typically require multiple sequential steps—including spin coating, mask alignment, exposure, development, and etching—as well as tightly controlled conditions and specialized tools. These complex requirements hinder scalability and allow the fabrication of only small, flat, and rigid substrates, thus limiting their application to large-area, curved, or flexible formats. To overcome these limitations, fabrication strategies that can integrate structural topologies and functional liquids across multiple length scales while remaining compatible with scalable, high-throughput processes are required. Nature offers a compelling design principle based on hierarchical architectures that couple mechanical rigidity with adaptive liquid interfaces. Replicating this synergy could lead to the synthesis of multifunctional materials with advanced liquid processing features, such as droplet transport, guided evaporation, and responsive surface adhesion.

In this study, we fabricated slippery-architecture materials with controlled structural scales by combining photopolymerization-induced multiphase materials and light-based digital printing. Through simple photoinduced grafting, a dynamic liquid interface is embedded with strong affinity into digitally controlled three-dimensional (3D) microstructured materials. This approach results in a versatile platform for multiple scales of structural control adapted to biomimetic design, enhancing liquid manipulation, droplet evaporation, and the design of biomedical microfluidic chips. Our study represents a significant advancement in the practical application of liquid-based materials, demonstrating the potential of architected slippery surfaces with control over multiple structural scales.

Results

Photopolymerization-assisted phase-separated or entangled polymer synthesis

As illustrated in Fig. 1, slippery architectural materials originate from photopolymerization-induced multiphase materials. Creating a hierarchical structure spanning from the nanoscale to microscale by combining materials is an effective way to achieve a framework for liquid-based materials. The self-assembly strategy allows the formation of liquid-based materials via the autonomous organization of liquid- and solid-phase components into structured patterns. One such approach is polymerization-induced phase separation or entanglement of polymer mixtures, which leads to the encapsulation of functional liquids within solid-structured materials. Photopolymerization-induced phase separation (PIPS) results in a polymer-rich phase that forms a porous matrix and a solvent-rich phase, creating porosity that typically yields simple macroscopic geometries and homogeneous porous properties (Fig. 1a). In addition to their nanoporous structures, organogels consisting of crosslinked polymer networks infused with organic liquids as the fluid phase are promising liquid-based materials (Fig. 1b). In this study, we demonstrated a facile strategy for fabricating phase-separated or entangled polymers via photopolymerization in a mixture of curable (photocurable acrylate-based resin) and non-curable liquid (polyethylene glycol-200 (PEG-200)) polymers. Following photopolymerization, the phase-separated polymer was washed to remove the uncured liquids, resulting in the formation of nanoporous structures. Organogels are formed through the swelling and entanglement of uncured liquids into networks of crosslinked polymers. After polymerization, multiphase materials consisting of phase-separated polymers and organogels can be bonded with functional brushes to form slippery interfaces. Silicone oil was selected as the lubricating fluid in this study owing to its chemical stability and small environmental impact. Moreover, the infused silicone oil can react with appropriate terminal molecules, forming a hydrophobic and lubricant-infused slippery polydimethylsiloxane (PDMS)-grafted layer at the interfaces of multiphase materials, including nanoporous structures and organogels. In this study, photocurable acrylate-based materials and PDMS materials were used to produce phase-separated nanoporous structures and organogels, respectively. To facilitate the reaction of the PDMS-grafted layer with silicone oil, the nanoporous structures were initially functionalized with hydroxyl (–OH) groups before the infusion of the lubricant liquids (details are presented in the Methods section). Subsequently, slippery interfaces can be formed on these liquid-infused nanoporous structures and organogels through photoinduced grafting, leading to the formation of covalently bonded PDMS brushes on the structured surfaces28,29,30 and rendering the surface hydrophobic. Upon exposure to ultraviolet (UV) light, silicone oil dissociates and is then grafted onto –OH groups on nanoporous surfaces and –CH3 functional groups of entangled or crosslinked PDMS on organogel surfaces30,31, as illustrated in Fig. 1a and b. The remaining silicone oil functioned as a stable, thin lubricant layer, resulting in the development of slippery interfaces. As these processes of polymerization and grafting depend on light-based manufacturing, they allow simpler and more scalable fabrication of slippery interfaces (Fig. 1c). Interestingly, compatibility with light-based manufacturing technologies such as nanoimprint lithography (NIL)32,33 and digital light processing (DLP) 3D printing provides a unique platform for integrating liquid-infused slippery interfaces into architectural surfaces and materials. Thus, by leveraging the combined advantages of light-based microfabrication and multiphase material systems, the proposed photoinduced process can create hydrophobic and liquid-infused slippery interfaces with various dimensions and topologies, including flat or porous structures, designed microstructures, and even 3D objects, providing design flexibility at the macroscale. This allows the seamless integration of slippery interfaces into a wide range of architectural materials for diverse applications, as depicted in Fig. 1. Hereinafter, we denote the PIPS- and organogel-based slippery interfaces as P-S and O-S, respectively.

Fig. 1: Conceptual images of slippery architected materials.
Fig. 1: Conceptual images of slippery architected materials.
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a Photopolymerization-induced phase separation-based slippery structure (P-S), acrylate-based material with a high fabrication resolution and hardness from nanoporous structures infused with lubricants, for digitally patterned surfaces. b Organogel-based slippery structure (O-S), simply fabricate using an PDMS-based material without trichloro(octadecyl)silane (OTS) vapor-deposition (details in “Methods” section), derived from entangled polymer mixtures featuring crosslinked networks with an infused organic liquid phase. c Versatile application of replicated slippery interfaces: O-S for large-area planar and micropatterned surfaces.

Wetting and adhesion properties of 2D slippery surfaces

To evaluate the slippery properties of the fabricated P-S and O-S surfaces, we quantitatively analyzed the sliding angle and speed of droplets with various viscosities and surface energies, including fluorocarbon oil, water, milk, olive oil, and honey (Fig. 2a–c and Supplementary Fig. 2). Because of the stabilization of the thin lubricant layer on the PDMS-grafted brushes, the slippery surfaces exhibited enhanced liquid repellency. Thus, the sliding angles of various liquid droplets (5 μL) on the slippery surfaces were below 5°, and pinning was not observed (Fig. 2a). Time-lapsed images indicated effective liquid repellency and the absence of staining on the slippery surfaces (Fig. 2c and Supplementary Movies 1–3). Additionally, the P-S surfaces exhibited slightly smaller sliding angles and higher sliding speeds than those observed on the O-S surfaces owing to the smaller solid fraction of the P-S surfaces resulting from their nanoporous structures (Supplementary Fig. 1). In addition to the liquid repellency, our slippery surfaces significantly reduced the strength of ice adhesion. Figure 2d compares the ice adhesion strengths for different surfaces (with different surface lubrication conditions) measured using a custom-made apparatus (Supplementary Fig. 4). The strong adhesion of ice to the acrylate-based nanoporous and PDMS-based planar surfaces is attributed to solid (ice)–solid adhesion. For the organogel surface, although no clear lubricant layer is detected in the outermost region, we expect that the surface may be composed of mobile liquids and polymer end groups of crosslinked PDMS networks34. Owing to the pre-infusion of lubricating oils as the fluid phase, the solid-like state in the crosslinked PDMS surface can change to a liquid-like state on the organogel surface because of the liquid released from the PDMS matrix to the outer surface by the mobile liquid layer. Therefore, the lubricating liquid content induces a lower cross-linking density in the PDMS matrix, significantly reducing the ice adhesion strength, as shown in Fig. 2d. Moreover, because the lubricating layer prevents direct contact between the ice and substrates, the slippery surfaces exhibit ultralow ice adhesion strengths, which are attributed to solid–liquid adhesion. Our slippery surfaces also demonstrated high transparency at visible wavelengths (Fig. 2e, f) owing to the matched refractive indices of the lubricating and substrate materials. These results suggest that the simple and scalable fabrication process based on light-based manufacturing (Fig. 2e) is suitable for optical devices, windows, and sensing devices35,36,37,38.

Fig. 2: Evaluation of slippery surface performance.
Fig. 2: Evaluation of slippery surface performance.
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a Measured sliding angles of various liquids (fluorocarbon oil, water, milk, human serum, olive oil, and honey) on P-S and O-S surfaces (tilting speed: 0.8°/s). b Sliding speeds of different liquids (tilting angle: 30°). c Time-lapsed images showing liquid repellency and the absence of staining on slippery surfaces. Scale bar: 20 mm. d Ice adhesion strength measurement on the various surfaces (pushing speed: 1.47 μm/s). e Fabricated large-scale O-S (300 × 800 mm2). Scale bar: 100 mm. f Measured light transmittance values for the slippery surfaces and a PET film. Bars represent mean values, and error bars indicate mean ± SD (n = 5 independent experiments).

Digitally patterned slippery surfaces

To engineer surfaces for effective liquid manipulation, designing structures with slippery interfaces is crucial. As a conceptual demonstration of liquid manipulation, the acrylate-based multiphase resins were digitally polymerized onto a widely used transparent hydrophilic polyethylene terephthalate (PET) substrate (Fig. 3a). Micropatterned porous surfaces with various shapes, including a cartoon depicting sliding motion, a leaf pattern, the letters “CWNU,” a quick response (QR) code, and anisotropic microgrooves, can be obtained through UV irradiation using designed digital images (Fig. 3b–f). After infusing and grafting the lubricant oils, the digitally patterned porous areas are transformed into slippery surfaces that have small sliding angles and are pinning-free. This approach facilitates digital patterning of wetting properties to prepare locally confined patterned slippery regions because the lubricating liquid is firmly locked in designated areas with porous structures, unlike in the case of nonpatterned planar surfaces, owing to the capillary force. This phenomenon was confirmed by the increased optical transparency of the liquid-infused patterned slippery surfaces, compared with that of the non-infused microstructured porous surfaces, which exhibited significant scattering (Fig. 3b). By selectively patterning surfaces with hydrophilic or slippery features, we can spatially control the liquid patterns. Through these patterned wetting properties, the distinct ability of the slippery structures to create liquid patterns, when water is dropped onto both the microstructured porous and slippery surfaces, is demonstrated (Fig. 3c). Owing to the strong liquid repellency of the slippery surfaces, water droplets can easily slide from the slippery areas (Fig. 3d) and are confined to designated nonpatterned hydrophilic regions, whereas the micropatterned porous surfaces spontaneously absorb the liquid into their nanoscale pores. Moreover, by harnessing the spontaneous assembly of liquid patterns through the designed wetting properties, we demonstrated a high-resolution liquid QR code pattern with intricate structures, as shown in Fig. 3e. More interestingly, the patterned slippery surfaces can be engineered into anisotropic surfaces featuring a wetting gradient for directional liquid transport. We fabricated an anisotropic microgrooved (width: 249.4 ± 7.0 μm) slippery surface capable of easily controlling the anisotropic sliding of water droplets (Fig. 3f and Supplementary Movie 1). When slightly tilted on an anisotropic slippery surface, the water droplet can easily glide in the direction parallel to the line arrays (slippery-on); however, it is pinned onto the surface perpendicular to the line arrays (slippery-off). The anisotropic grooves act as barriers that restrict the water droplets and guide directional sliding. To demonstrate the liquid manipulation capability of slippery microgrooves, water microdroplets were sprayed on both the nanoporous and slippery microgrooved surfaces (Fig. 3g). The porous microgrooved surface absorbed water, resulting in randomly distributed droplets without specific alignment along the line array. In contrast, the slippery microgrooves exhibited water droplets sliding on periodic lines, with the liquid aggregating in the nonslippery area and aligning along the line array. These patterned slippery surfaces are promising for the manipulation of liquid droplets for directional water collection39,40, liquid transport41,42, and microfluidic devices43.

Fig. 3: Digitally patterned slippery surfaces for liquid manipulation via DLP.
Fig. 3: Digitally patterned slippery surfaces for liquid manipulation via DLP.
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a Schematic of DLP setup. b Various digitally patterned surfaces (i) before and (ii) after lubricant infusion and grafting. c Water drop tests on (i) porous surfaces, which spontaneously absorb liquid into nanoscale pores, and (ii) slippery surfaces, which allow liquid patterning. d Water droplet sliding test on a slippery surface: (i) sliding off slippery area and (ii) accumulating in designated hydrophilic regions. e Formation of a high-resolution liquid QR code pattern. f Anisotropic microgrooved slippery surface designed for directional control of water-droplet movement ( ~ 50 μL, tilting angle: 30°): (i) droplet pinning perpendicular to groove lines (slippery-off) and (ii) gliding parallel to groove lines (slippery-on). g Comparison of sprayed water droplet behavior on (i) nanoporous and (ii) slippery microgrooved surfaces. All scale bars: 5 mm.

Imprinted slippery microstructures

Beyond the 2D patterning of wetting properties, slippery interfaces can be integrated into 3D microstructures. In this study, two representative slippery microstructures were fabricated using the well-known scalable fabrication process of UV NIL (Fig. 4a; details are presented in the “Methods” section)44,45. These structures included interconnected microcavities with vertical walls (hexagonal grid pattern) and V-shaped asymmetric slopes (inverted pyramid pattern). The interaction between liquid manipulation and imprinted slippery microstructures can be leveraged to enhance sensing and diagnostic platforms by controlling the evaporation patterns of liquid droplets46,47. Figure 4b illustrates the distinct evaporation behavior of colloidal droplets containing polystyrene nanoparticles dispersed in deionized (DI) water on the slippery hexagonal grid pattern. Hexagonal grid pattern can maintain stable air pockets to exert liquid repellency owing to the inherent structural benefits of interconnected shared walls and isolated cavities48,49. Regardless of the wettability of the constituent material, the strong pinning of the microcavities, which is attributed to the large contact-angle hysteresis due to the concave structural topography with sharp edges, results in a constant-contact radius mode and spatial stabilization of the evaporating sessile droplet (Fig. 4c, d (i), (ii)). This phenomenon leads to a coffee-ring formation of dried particles (Fig. 4e (i), (ii)), which allows droplet-evaporation-induced particle enrichment in analytical sensing platforms. In contrast, the presence of a slippery interface on the hexagonal grid pattern creates liquid–air interfaces (i.e., slippery Cassie interfaces), instead of solid–air interfaces (i.e., Cassie interfaces)50, and consequently, the energy barrier required to resist the movement of evaporating droplets is reduced. This results in a nearly pinning-free constant-contact angle mode while maintaining stable air pockets for liquid repellency (Fig. 4c, d (iii)). Consequently, the slippery hexagonal grid pattern resulted in a smaller extent of aggregation and higher concentrations of deposited particles (Fig. 4e (iii-iv)), which enhanced the intensity of sensing signals in fluorescence or Raman detection51. We integrated a slippery interface into microcavity structures with asymmetric topography for directional and spontaneous microdroplet transport, resulting in directional particle aggregation (Fig. 4f–h). To study the evaporation behavior of the inverted pyramid pattern, microdroplets were sprayed onto substrates (Fig. 4f). Prior research indicated that inverted pyramid patterns using hydrophobic materials effectively trapped viruses in microcavities, reducing infectious disease transmission46. However, this method faced challenges with liquids containing organic components, as hydrophobic surfaces exhibited strong pinning effects with biological fluids, impeding droplet mobility and particle aggregation. Additionally, hydrophobic surfaces could not inactivate captured particles, limiting antimicrobial efficacy. To overcome these issues, this study combined an inverted pyramid pattern with a slippery interface to enhance droplet mobility and particle aggregation efficiency. CuO nanoparticles, known for their antimicrobial and antiviral properties52,53, were selectively coated inside the microcavities (Fig. 4g, Supplementary Figs. 5, 6) by spraying a colloidal CuO nanoparticle solution in DI water three times, followed by natural evaporation. The structure’s performance was evaluated using colloidal droplets with polystyrene microparticles (~2 μm) in DI water to simulate bacterial particles (Supplementary Fig. 7). These droplets were sprayed onto the planar hydrophilic (acrylate-based), hydrophobic (PDMS-based), and slippery (O-S) surfaces, and their aggregation behavior was systematically compared. Experimental results revealed that on both hydrophilic and hydrophobic surfaces, droplets exhibited strong pinning at the top and edges of patterns, hindering effective particle aggregation within microcavities. Conversely, the slippery interface allowed smooth droplet movement into cavities, enabling stable particle aggregation. The structure achieved an approximate capture efficiency of 98%, confirmed via a tape peel-off test (Supplementary Fig. 7). Similar results were observed with colloidal droplets containing polystyrene microparticles in artificial human saliva, indicating this method’s potential in aggregating and possibly inactivating pathogens (Fig. 4h). These findings emphasize the potential of integrating slippery interfaces with microstructured patterns to enhance particle capture and inactivation, thus preventing pathogen transmission. Additionally, the results highlight the broader application scope of slippery interfaces in 3D microstructures for manipulating liquid evaporation and deposited particle patterns, underscoring their ability to advance the development of functional materials for biomedical54 and water-harvesting applications55,56.

Fig. 4: Microimprinted slippery surfaces for advanced liquid manipulation and particle aggregation using UV NIL.
Fig. 4: Microimprinted slippery surfaces for advanced liquid manipulation and particle aggregation using UV NIL.
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a Schematic of the UV NIL and b Colloidal droplet evaporation on slippery hexagonal grid pattern. c Changes in contact diameters over time on hydrophilic, hydrophobic, and slippery hexagonal grid patterns. Data points represent mean values, and error bars indicate mean ± SD (n = 5 independent measurements). d Time-lapse images showing droplet contact modes on (i) hydrophilic, (ii) hydrophobic, and (iii) slippery hexagonal grid patterns. Scale bar: 300 μm. e Evaporation results of colloidal droplets on (i) hydrophilic and (ii) hydrophobic hexagonal grid patterns, showing the strong coffee-ring effect, and (iii) slippery hexagonal grid pattern, with higher concentrations of deposited particles. (iv) Magnified view of the deposited particles shown in (iii). Scale bar: 500 μm (i-iii); 20 μm (iv). Data are representative of 5 independent experiments with similar results. f Schematic of slippery interfaces in an inverted pyramid pattern guiding and directionally aggregating microdroplets. g Image of the CuO-coated slippery inverted pyramid pattern. Scale bar: 20 μm. h Evaporation results of artificial human saliva-based colloidal microdroplets on (i) hydrophobic and (ii) CuO-coated slippery inverted pyramid patterns. Scale bar: 20 μm. Data are representative of 5 independent experiments with similar results.

3D-printed slippery structures

In addition to imprinted slippery microstructured surfaces, the compatibility with DLP 3D printing (Supplementary Fig. 8) allows for the creation of liquid-infused 3D slippery materials, enhancing the proposed light-based fabrication method for applications like bioinspired microfluidics12 and biomedical devices56,57. To confirm this capability, 3D-printed slippery microfluidic chips with asymmetric channel geometry (Fig. 5a–c, e) were designed for autonomous droplet transport without external energy (Fig. 5d, f). Two types of 3D slippery microfluidic chips (SlipChip) were fabricated using DLP 3D printing of photocurable PDMS-based organogels: a trichannel multilayer SlipChip (Fig. 5a) and dual-channel single-layer SlipChip for merging and mixing droplets (Fig. 5b). These chips feature slippery interfaces that lower the energy barrier for liquid transport in enclosed structures. The lubricated asymmetric channels enable autonomous droplet transport driven by a Laplace pressure gradient, inspired by natural systems like cacti, shorebirds, and spider silk12,58. To demonstrate autonomous liquid transportation via slippery asymmetric channels, three differently colored water droplets (blue, orange, and green) were loaded into each inlet of the trichannel multilayer SlipChip (Fig. 5d and Supplementary Movie 2, t = 0 s). The droplets moved along their channels and converged at the intersection (Fig. 5d, t = 80 s), completing their paths subsequently (Fig. 5d, t = 100 s). These multilayered slippery channels can serve as drug toxicity testing chips by placing cell-cultured membranes between the channels, minimizing drug loss and ensuring efficient performance57. In contrast, hydrophobic organogel-based fluidic chips showed no droplet movement due to large contact angle hysteresis (Supplementary Fig. 8 and Supplementary Movies 3, 4). To verify the autonomous transport functionality of slippery asymmetric channels in the dual-channel SlipChip, human serum and milk were loaded into inlets (Fig. 5f, t = 0 s). The droplets autonomously moved to the center and mixed thoroughly (Fig. 5f, t = 147.7 s; Supplementary Movie 5). This functionality offers a comprehensive microfluidic platform essential for efficient liquid transport in biomedical devices59,60 and clinical diagnostics12. Additionally, the antifouling properties of the slippery 3D structure were evaluated by fabricating spatula-shaped structures and immersing them in ketchup. The hydrophobic organogel-based structure showed significant contamination, while the slippery 3D structure resisted fouling and remained clean (Supplementary Fig. 10 and Supplementary Movie 6). These results demonstrate another benefit of the light-based manufacturing process for PDMS-based slippery 3D structures. This method simplifies the monolithic fabrication of transparent PDMS devices with slippery interfaces, eliminating multiple steps of conventional PDMS fabrication, and provides flexibility in creating various channel structures and assembling different parts (Supplementary Fig. 8).

Fig. 5: Demonstration of DLP 3D printed slippery microfluidic chips enabling autonomous liquid transport.
Fig. 5: Demonstration of DLP 3D printed slippery microfluidic chips enabling autonomous liquid transport.
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a Schematic illustration of a trichannel multilayer SlipChip and b Dual-channel single-layer SlipChip with asymmetric channel geometry enabling energy-free liquid movement via Laplace pressure gradient. c Fabricated trichannel multilayer SlipChip. d Visualization of water transport in each channel of the trichannel multilayer SlipChip. e Fabricated dual-channel single-layer SlipChip. f Transport of biological fluids (human serum and milk) through each channel of the dual-channel single-layer SlipChip. All scale bars: 5 mm.

Discussion

In summary, we developed a comprehensive strategy for integrating slippery interfaces into complex structures to leverage the structural and interfacial benefits of slippery-architecture materials. This integration was achieved via the digital fabrication of polymerization-induced multiphase resins together with photoinduced grafting. The combination of photoinduced polymerization and grafting allows the formation of multiphase materials comprising solid–liquid composites, facilitating the stable bonding of the liquid-phase material within a solid. These digitally controlled slippery architecture materials represent a concept for engineered surfaces, including scalable and transparent slippery surfaces designed for ultralow adhesion of liquids and solids, anisotropic microstructured slippery surfaces facilitating unidirectional liquid manipulation, digitally patterned wettability for creating liquid patterns, imprinted slippery microcavity structures allowing the control of droplet evaporation, and 3D-printed slippery structures designed for biomimetic microfluidic chips with autonomous liquid transport. Although the proposed approach is simple and effective for creating slippery structured materials with design freedom, in the present implementation, limitations may arise from the digitally patternable feature resolution of the photocurable PDMS-based organogel resins, which were used to demonstrate the multiphase material process in this study. The photocurable PDMS material was optimized for imprint mold fabrication and self-replication, owing to its high optical transparency. Thus, controlling the curing thickness in the vertical direction during the layer-by-layer additive process becomes challenging, leading to limitations in geometric complexity and feature resolution when light-based 3D printing technologies are compared with imprint lithography. Nevertheless, to meet diverse functional requirements within these constraints, we employed two types of photocurable resins with complementary properties. The PDMS-based organogel resin (O-S), offering excellent transparency and flexibility, is suitable for fabricating large, millimeter-scale 3D structures. In contrast, the acrylate-based porous resin (P-S) can be used in DLP printing applications that require relatively high-fidelity surface textures and detailed pattern definitions. However, due to its brittleness after curing, P-S is less suitable for constructing mechanically robust, large-scale architectures. Combining the two materials—P-S for relatively fine surface patterning and O-S for flexible, larger-scale structures—we effectively leverage their respective strengths within the framework of a universal polymerization-induced multiphase material platform. Given the material-independent nature of this process, we anticipate that alternative photocurable systems with tailored chemical compositions may overcome the current limitations in both resolution and mechanical integrity, thereby expanding the capabilities of high-resolution light-based 3D printing. Another consideration is the mass production of slippery structures, which poses challenges that require further investigation. Although the scalable slippery surfaces were manufactured using a roll-to-plate imprinting approach in this study (Fig. 2e), we envision that the proposed photoinduced process is highly compatible with a continuous roll-to-roll approach44,49, which would allow the large-scale continuous mass production of slippery surfaces.

Overall, this paper introduces a light-based digital manufacturing strategy that addresses several long-standing challenges in the fabrication of slippery surfaces—including process complexity, limitations in shape programmability, insufficient scalability for large-area production, and instability of infused lubricants. Our approach—integrating photoinduced grafting with UV-curable systems such as DLP 3D printing and UV nanoimprint lithography—surpasses traditional implementations of slippery surfaces. The proposed unified platform for producing structurally complex, functionally robust, and scalable slippery surfaces offers a technically advanced and practical surface engineering solution for real-world applications, marking a significant step toward the development of versatile platforms for bioinspired liquid manipulation.

Methods

Photoinduced grafting process

A custom-made UV lamp (BDP-231005, BlueDP Co., South Korea) (Supplementary Fig. 12) was used to expose the surface to UV radiation with thermal energy, inducing the dissociation of silicone oil molecules and subsequent grafting onto functional groups of the substrates. For the nanoporous surfaces, trichloro(octadecyl)silane (OTS; Sigma–Aldrich, USA) coating was first applied, and hydroxyl (–OH) groups were generated by UV ozone treatment for 20 min prior to grafting, yielding PDMS-grafted OTS layers. For the organogel surfaces, methyl (–CH3) groups are inherently present in the PDMS backbone, and therefore, no additional surface treatment was required to obtain a PDMS brush layer30,31. We measured the required UV power at wavelengths of 207, 214, 296, 317, and 321 nm for forming the PDMS brush layer29,30 using a digital optical power meter (PM100D, Thorlabs, Inc., USA) and a photodiode power sensor (S120VC, Thorlabs, Inc., USA). The lamp power was set to 70 W, and the lamp was placed at a distance of 30 cm. The measured intensities of the light at wavelengths of 207, 214, 296, 317, and 321 nm were 149.1 ± 0.4, 155.0 ± 0.3, 124.8 ± 0.2, 93.1 ± 0.3, and 89.4 ± 0.2 mW/cm2, respectively. According to these results, we exposed the surface to UV irradiation with thermal energy for 15 min to perform photoinduced grafting, which resulting in the formation of covalent bonds between the –CH3 or –OH groups and silicone oil.

Fabrication of PIPS-based slippery interfaces

We used a photocurable acrylate-based resin (MINS-311RM, Minuta Technology, South Korea) as the polymer-rich phase, which was combined with the non-curable polymer PEG-200 (Tokyo Chemical Industry Co., Ltd., Japan)—a solvent-soluble material—to create phase-separated nanoporous structures filled with silicone oil (KF-96-10CS, Shin-Etsu Polymer Co., Ltd., Japan) within the nanopores (Supplementary Fig. 1). The process was initiated by mixing the liquid acrylate-based resin with 50 wt% PEG-200 at room temperature and stirring the mixture at 500 rpm for 5 min. This mixture was spread between a substrate and fluorinated ethylene propylene (FEP) release film via the roll-to-plate method under a force of approximately 10 kgf and then exposed to UV light (λ = 365 nm) at 180 mJ/cm2 via DLP or UV NIL to solidify the acrylate-based resin. After curing, the FEP release film was removed, and the surface was cleaned with isopropyl alcohol and DI water. Subsequently, the uncured PEG-200 was replaced by immersing the sample in DI water for 1 h, followed by drying at 70 °C to form nanoporous structures. To make the hydrophilic nanoporous structures hydrophobic, we applied oxygen plasma cleaning (UVC-30, Jaesung Engineering Co., South Korea) for 20 min to generate –OH groups, onto which we vapor-deposited a layer of trichloro(octadecyl)silane for 40 min at 120 °C using a hotplate (PC-420D, Corning Inc., USA). Before silicone oil coating, additional oxygen plasma cleaning was conducted for 20 min. Subsequently, silicone oil was applied to the surface approximately 15 μL/cm2 using a micropipette, and photoinduced grafting was conducted. Subsequently, excess silicone oil was removed by tilting the sample (30°) for 30 min, resulting in a slippery structure with a trichloro(octadecyl)silane layer and silane-bonded PDMS brushes that effectively trapped the silicone oil. A schematic of the fabrication process is shown in Supplementary Fig. 13.

Fabrication of organogel-based slippery interfaces

The proposed method is simpler than that of P-S fabrication. Initially, for organogel fabrication, we mixed a photocurable PDMS material (MINS-UV PDMS, Minuta Technology, South Korea) with 50 wt% silicone oil and stirred the mixture at 500 rpm for 5 min. This mixture was then exposed to UV light (λ = 365 nm) at 7000 mJ/cm2 using DLP or UV NIL to solidify the photocurable PDMS material. Following this, silicone oil was applied to the surface approximately 15 μL/cm2 using a micropipette, and photoinduced grafting was conducted. Subsequently, excess silicone oil was removed by tilting the sample (30°) for 30 min, resulting in a slippery structure with a covalently bonded PDMS brush layer that effectively trapped the silicone oil. A schematic of the fabrication process is shown in Supplementary Fig. 14.

Fabrication of digitally patterned slippery surfaces

The PIPS mixture consisting of a photocurable acrylate-based resin mixed with 50 wt% PEG-200 was spread between a PET film and an FEP release film and then adjusted to a uniform thickness of 3.5 ± 1.1 μm using the roll-to-plate method under a force of approximately 10 kgf. The specimen was then placed on the window of a DLP 3D printer (IMD, Carima Co., South Korea), where a digital UV image was projected at an exposure intensity of 180 mJ/cm2 to create digitally patterned structures directly on the PET film, which were revealed upon removal of the FEP release film. After the surface was cleaned with isopropyl alcohol and DI water, it was processed using the P-S fabrication method.

Fabrication of imprinted slippery microstructures

Two types of microstructures were fabricated via UV NIL using photocurable PDMS-based organogel. The hexagonal grid pattern featured a pitch of 69 ± 0.3 μm, width of 2.2 ± 0.2 μm, and height of 7.3 ± 0.2 μm, whereas the inverted pyramid pattern had a pitch of 51 ± 0.3 μm, width of 1.6 ± 0.2 μm, and height of 31.6 ± 0.6 μm. To remove the silicone oil from the cavities of the microstructures and excess oil on the surface, a thermal PDMS pad was pressed against the specimen for 5 min, allowing excess silicone oil to be absorbed into the pad61, which resulted in the fabrication of slippery microstructures.

Fabrication of 3D-printed slippery microfluidic chip

The 3D slippery structures were fabricated using O-S and a custom-made DLP 3D printer with a DLP engine (NVR2 + , Burms, Germany), which had a UV power of 10 mW/cm² (λ = 365 nm). An aluminum build plate was used because of its reflective properties, which allowed efficient curing of each layer within 90 s (900 mJ/cm²). However, photocurable PDMS materials are not ideally suited for 3D printing, because of their reduced resolution, extended exposure times, and the challenge of forming enclosed structures, such as microfluidic chips, in a single step, as the filled resin in the channel tends to cure during printing of the next layer, e.g., the closed part. To address this limitation, we increased the layer thickness to 1.5 mm (dual-channel single-layer SlipChip) and 1.0 mm (trichannel multilayer SlipChip) to reduce the processing time and separately manufactured the channel and closing parts before assembling them into a microfluidic chip. This approach allowed the assembly of organogel-based slippery 3D parts for constructing slippery microfluidic chips with asymmetric channels (Fig. 5). Each fabricated component was immersed in a silicone oil bath for 1 h and then subjected to photoinduced grafting. Subsequently, excess silicone oil was removed by tilting the sample (30°), and the components were assembled to complete the autonomous droplet transportation channels.

Sliding angle and speed

The sliding angle and speed were measured using a liquid-droplet analysis tool (SmartDrop; Femtofab Co., Ltd., South Korea). Droplets—each with a volume of 5 μL—were placed on the surface using the sessile drop method, and the sliding angle was determined in a dynamic state, with the specimens being tilted at a rate of 0.8°/s. Then, the sliding angle was recorded as the angle at which the stabilized droplets began to slide. The sliding speed was calculated by measuring the time taken for a 5 μL droplet to travel 8 mm from a static state, with the specimen tilted at an angle of 30°. All values are presented as mean ± SD, and n = 5 independent measurements were performed.

Ice adhesion strength

A cuvette with a 10.25 mm diameter was positioned on the surface, and 0.25 mL of water was injected into it. The surface was then cooled to approximately –15 °C using a Peltier cooling device, and this cooling process lasted 3 min. The maximum force was measured by pushing the cuvette horizontally at a speed of 1.47 μm/s. Data are reported as mean ± SD, with n = 5 independent measurements.

Light transmission

The light-transmission spectra of the samples were recorded between 300 and 800 nm using a UV/vis/NIR spectrophotometer (V-770, JASCO Co., Japan) with an integrating sphere attachment.

Preparation of human serum mixture

Human serum (Sigma-Aldrich, H4522, USA) derived from a sterile-filtered human-male AB plasma was diluted to a concentration of 10% (v/v) using deionized water for use in the sliding tests. As the human serum used in this study was commercially sourced and de-identified, no informed consent or Institutional Review Board (IPB) approval was required.

Preparation of colloidal solution and evaporation test

For the experiments, three colloidal solutions, including CuO nanoparticles dispersed in DI water, polystyrene nanoparticles (Carboxylate-Modified Microspheres, ~0.2 μm, Thermo Fisher Scientific Inc., USA) in DI water, and polystyrene microparticles (Carboxylate-Modified Microspheres, ~2 μm, Thermo Fisher Scientific Inc., USA) dispersed in DI water or artificial human saliva, were prepared. The CuO nanoparticle solution (25–55 nm, US Research Nanomaterials, Inc., USA) was prepared by diluting the nanoparticles in DI water to a concentration of 0.5 wt%. Polystyrene nanoparticle and microparticle solutions were prepared by mixing the particles with a solvent and diluting to a concentration of 2.5% (v/v). For the evaporation tests, the contact angles and diameters of the droplets were measured using a liquid-droplet analysis tool. A laser confocal microscope (VK-X200, Keyence Co., Ltd., South Korea) was employed to visualize particle aggregation after evaporation. A colloidal sessile droplet of approximately 5 μL was placed onto a hexagonal grid pattern, and the evaporation process was monitored at room temperature and 15% relative humidity (RH) using the liquid-droplet analysis tool equipped with a high-resolution camera. Each experiment was performed five times to ensure reliability and reproducibility of the results. Additionally, for spray experiments on the inverted pyramid pattern, droplets were applied using an air compressor pressurized to 3 bar and an airbrush with a nozzle size of 0.3 mm. The colloidal solution was sprayed in three bursts with one-second intervals, followed by allowing evaporation at room temperature and 15% RH.

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.