PDMS Layer Research Articles

Fabrication of high performance BaSnO3/PVDF piezoelectric nanogenerator through high surface area BaSnO3 nanoparticle assisted β-phase stabilization of PVDF

Piezoelectric nanogenerators (PENGs) are becoming increasingly popular for energy generation and their use in smart electronics. In this study, a barium stannate (BaSnO3)-doped polyvinylidene fluoride (PVDF)-based PENG has been fabricated for the first time. The β-phase of PVDF was stabilized by optimizing the doping of BaSnO3 nanoparticles without the need for external electrical poling. The high surface area of the BaSnO3 nanoparticles promotes the nucleation of the polar β-phase in PVDF through electrostatic interaction. A low-cost solution casting method was used to prepare flexible BaSnO3/PVDF nanocomposite containing 5 wt% BaSnO3, which was then shaped and sandwiched between copper electrodes and protected with a thin PDMS layer to create the final PENG. The fabricated PENG can generate up to ∼41 V of voltage, ∼1.51 µA of current and ∼18.1 µW/cm2 of power density when ∼15.7 kPa pressure is applied by a human finger. The PENG can also charge capacitors, power up 16 LEDs in a series connection, and power other small electronics such as wristwatches, speakers, and calculators. Additionally, the PENG can activate the electrochromic material methyl viologen, which is commonly used in smart window applications.

High-performance and robust biomimetic triboelectric nanogenerators for energy harvesting and self-powered wearable tactile sensing

High-performance and robust Triboelectric nanogenerators (TENGs) with biomimetic micro-structured PDMS and nanostructured aluminum as main tribo-layers have been proposed. Leaf of Calathea Zebrina plant is used as a mold to prepare PVA template which is further used to obtain micro-structured PDMS layer whereas nanostructures on aluminum surface have been created by water-assisted oxidation process. Corresponding TENG assembled in vertical contact-separation mode produces VOC ∼430 V and ISC ∼45 μA with high power density of 8.89 W m−2. Excellent performance stability observed at least over 20,000 cycles and up to 120 days is another remarkable feature of the proposed TENG. Further, these TENGs are found highly viable as self-powered wearable tactile sensors for several hand and foot-based tactile activities, which can precisely record spatial and temporal details of the activity. Such TENG development strategies, which involve mimicking of natural micro-patterns have huge performance potential and may play an integral role to augment commercial prospects of TENGs in their wide application spectrum.

Construction of PDMS@ZIF-8 composite membrane on PVDF hollow fiber inner surface for ultrafast ethanol/water separation

Construction of ultra-thin and defect-free separation membrane on inner surface of hollow fiber supports is significant but challenging for molecular separation. In this study, the highly permeable PDMS@ZIF-8/PVDF composite membranes were successfully fabricated upon the inner-surface of polyvinylidene fluoride (PVDF) hollow fiber membrane for pervaporation (PV) ethanol/water separation. The efficient preparation of hierarchical PDMS@ZIF-8/PVDF composite membranes benefited from the precise regulation of ZIF-8 layer through interfacial synthesis and sequential coating of PDMS matrix. The thickness of the PDMS layer was only 16 ± 2 nm, which admirably eliminated the non-selective defects in ZIF-8 layer. Owning to the optimal combination of MOF layer and ultra-thin polymer layer, the as-prepared membrane exhibited the excellent ethanol flux of 1.34 kg m−2 h−1 with an ethanol concentration in permeate of 31.3 wt% for separating 5 wt% ethanol aqueous solution at 40 °C. The separation performance of the resultant membrane was superior to that of the other ethanol selective PV membranes. These findings herein provided a new way for preparing high-performance hollow fiber composite membranes for PV separation.

Electricity/light-heat-hygro multi-responsive soft luminescent systems for rewritable and programmable information display

Rewritable luminescent materials are attracting widespread attention for information storage and display as they can help to reduce environmental wastes caused by the abuse of single-use and transient systems. Nevertheless, since most reported systems are chemical-stimuli-responsive and single-stimuli-responsive, it remains challenging to achieve the rewritable and programmable display of multiple information in one single system, which is essential to enhance information richness and display intelligence. In this work, an ideal kind of multi-responsive soft luminescent display systems are reported, which consist of heat/humidity-responsive fluorescence-phosphorescence dual-emission film and stacked graphene assembly (SGA) film by using thin poly (dimethyl siloxane) (PDMS) as middle connecting layer. In such multilayer structure, the heat generated by electricity connection or light illumination of bottom SGA film can be instantly transferred across the middle PDMS layer to cause heat-triggered red-to-blue emission color change, or to evaporate water for blue-to-red emission color recovery. Owing to the “residual-free” nature of these electricity, light and water stimuli, multi-responsive rewritability is guaranteed to enable the reversible writing and complete erasure of various letter/pattern information. On this basis, robust electricity/light-heat-hygro multi-responsive soft luminescent display systems are demonstrated, in which diverse letter/pattern information could be facilely programmed to be successively displayed and then completely reset to enable another data writing/erasing cycle by sequential modulation of different environmental stimuli. This study brings programmable merit for rewritable luminescent display systems and is expected to inspire more intelligent ones.

Development and investigation of a multilayer PDMS/zeolite composite membrane for CO2 separation applications

This work aims to investigate and develop a concept for CO2 separation based on PDMS/SSZ–13 (high-Si CHA) composite membranes. Firstly, an Al2O3 support was coated with SSZ-13 zeolite layer, then to increase the performance of the membrane, a Polydimethylsiloxane layer was effectively deposited homogeneously to cover the cracks and defects of the zeolite layer. The results of single gas permeation measurements displayed a notable increase in ideal CO2/CH4 selectivity up to 428 at the lowest PDMS concentration of 0.5 vol%. Moreover, a coating time of 10 min preserved CO2 permeance while increasing CO2/CH4 selectivity from 5 to 120. A twentyfold increase in CO2/CH4 selectivity was noted with mixed gas permeation without a reduction in CO2 permeance. Quantitative and qualitative microscopic analyses were also carried out on the coated membrane to better understand its morphology and microstructure. The outcomes indicated that PDMS layer decreased the permeation of N2 and CH4 and enhanced surface affinity toward CO2, resulting in reduced defects in the zeolite membranes and enhanced selectivity for CO2/N2 and CO2/CH4.

Study and fabrication of rain triboelectric nanogenerator based on laser-induced graphene interdigital electrode

In this work, a rain triboelectric nanogenerator (R-TENG) based on a laser-induced graphene (LIG) interdigital electrode was developed to harvest rain energy. The R-TENG comprises a LIG interdigital electrode on a polymer substrate with a hydrophobic Polydimethylsiloxane (PDMS) layer as a protective layer. When raindrops fall onto the surface of the PDMS layer and move between two adjacent interdigital electrodes, the accumulated charges move back and forth, resulting in the generation of alternating current. The LIG pattern design and the energy collection efficiency were studied by altering the production parameters of the LIG electrode and measuring the droplet diameter on the PDMS surface. A R-TENG with an electrode width of 3 mm produces a laser power of 2.1 W, and an output voltage of 2.46 V is generated. The R-TENG could be applied as an additional energy source to harvest rain energy for agricultural IoT sensors.

Silicon ring resonator with ZIF-8/PDMS cladding for sensing dissolved CO2 gas in perfluorocarbon solutions

Precise measurement of dissolved CO2 gas concentration in perfluorocarbon (PFC) solution is essential to the implementation and understanding of extra-pulmonary gas exchange with liquid ventilation. While electrochemical and optochemical sensing methods are widely used for dissolved CO2 sensing in aqueous solution, dissolved CO2 sensing in the PFC solution remains largely unexplored. We report a refractive index-based silicon photonic sensor for monitoring dissolved CO2 gas in the PFC solution. The sensor employs a high-Q silicon ring resonator with ZIF-8 cladding for selective and sensitive detection of dissolved CO2 gas. Further, a gas-permeable PDMS coating layer is applied to the ZIF-8 cladding for enabling gas diffusion between the PFC solution and the ZIF-8. The PDMS layer does not dissolve in PFC and its hydrophobic properties help protect the ZIF-8 from potential damage caused by aqueous body fluids in the PFC solution during the liquid ventilation process. The fabricated sensor exhibits stable and repeatable responses in the PFC solution with a fine resolution of ∼0.16 CO2 vol%, good selectivity for dissolved CO2 over dissolved O2, and a fast response time of ∼1.9 min, enabling reliable monitoring of dissolved CO2 gas level changes in the PFC solution.

Dome-Conformal Electrode Strategy for Enhancing the Sensitivity of BaTiO3-Doped Flexible Self-powered Triboelectric Pressure Sensor.

A microstructured surface has been applied in self-powered triboelectric pressure sensors to increase the charge-carrying sites and enhance the output performance. However, the microstructure increases the distance between the electrode and the triboelectric layer, and its influence on the output performance is unknown. Herein, we proposed a dome-conformal electrode strategy for a self-powered triboelectric nanogenerator (TENG) pressure sensor. With a simple reverse-dome adsorption process, an ultrathin triboelectric layer and Ag electrode can be made conformal to the dome PDMS structure. The TENG sensor is constructed with paper as a positive triboelectric layer. Compared with the device based on nonconformal structure, the conformal design strategy endows the device with a faster charge transfer and enhanced output voltage. By doping with BaTiO3, the outermost triboelectric layer can be easily modified to improve its ability of sustaining charge, and an ultrathin PDMS layer is coated on the triboelectric layer to expand the triboelectric polarity difference between two triboelectric layers so as to enhance the output voltage. The synergistic effects enable the optimized TENG sensor with a sensitivity of 0.75 V/kPa in the low-pressure region (0-26 kPa) and 0.19 V/kPa in the high-pressure range (26-120 kPa). Its application in human motion detection, grabbing water beakers, and noncontact distance testing has been demonstrated. This work provides a route such as a conformal structure design strategy to enhance the output performance of a microstructure-based TENG sensor.

Microfluidic magnetic detection system combined with a DNA framework-mediated immune-sandwich assay for rapid and sensitive detection of tumor-derived exosomes

Tumor-derived circulating exosomes (TDEs) are being pursued as informative and noninvasive biomarkers. However, quantitatively detecting TDEs is still challenging. Herein, we constructed a DNA tetrahedral-structured probe (TSP)-mediated microfluidic magnetic detection system (μFMS) to provide a rapid and sensitive platform for analyzing TDEs. CD63 aptamer-modified Fe3O4 magnetic nanoparticles (MNPs) were constructed to form magnetic nano-report probes (MNRs). The microfluidic chips were fabricated from glass functionalized with DNA TSP-modified aldehyde groups and a PDMS layer designed with serpentine microchannels. An induction coil-based magnetic detector was used to measure the magnetic signal. The linear dynamic range of the μFMS system for TDE assays was 1.98 × 103–1.98 × 107 particles/mL with a limit of detection of 1.98 × 103 particles/mL in PBS. There was no significant difference in TDE detection between the simulated serum and PBS, which indicated the feasibility of the constructed μFMS system for TDE analysis in complex biological systems. In terms of cost, reaction time and operation procedure, this μFMS has the potential to be developed as a clinical point-of-care testing tool for cancer diagnosis and therapeutics.

Miniature planar 3D ECT sensor based on distributed electrode arrangement

Due to the low sensitivity in the middle of sensing chamber of planar peripheral electrode arrangement tomography system, a miniature planar electrical capacitance tomography (ECT) sensor with distributed electrode arrangement is proposed for imaging of 3D cultivated cells. In this work, the 3D imaging capability of the proposed sensor was compared to the peripheral electrode arrangement ECT sensor through numerical simulation of the sensitivity maps. The analysis of the sensitivity maps revealed that the sensitivity distribution of proposed sensor covered the entire surface of the sensing chamber which indicated improved sensitivity coverage in the sensing chamber. In addition, the axial resolution and the singular value decomposition (SVD) analysis of the sensitivity maps demonstrated that the proposed sensor has better 3D imaging capability. Then, the proposed sensor composed of nine electrodes, a thin PDMS layer and a glass coverslip was fabricated and investigated. The experimental results showed that the reconstructed 3D image by the proposed sensor was consistent at all the test positions. In contrast to the planar peripheral electrode arrangement ECT sensor that has an average correlation coefficient (CC) of 0.4571, the proposed sensor achieved a higher average CC of 0.5454, indicating better 3D imaging performance.

Continuous motion of an electrically actuated water droplet over a PDMS-coated surface

Electrically actuated linear motion of a water droplet over PDMS-coated single active electrode is analyzed from detailed experiments and modeling. In an experiment, continuous motion of the droplet is achieved when it is located over an active electrode with a horizontal ground wire placed just above in an open-electrowetting-on-dielectric configuration. Using a CCD camera, the instantaneous centroid position of the droplet is determined and its velocity is inferred by numerical differentiation. The edge-detected image is also used to determine the advancing and receding contact angles of the moving drop relative to the substrate. Motion of 2, 6, and 10 µl water droplets for voltages in the range of 170–270 V DC is examined to investigate the effect of drop volume and voltage on drop deformation and velocity. The motion of the droplet is initiated by Young-Lippmann spreading at the three-phase contact line, followed by a nonuniform electric force field distributed between the active electrode and the ground wire localized at the droplet-air interface. Simulations carried out using COMSOL© Multiphysics with full coupling between the electric field and hydrodynamics are in conformity with experiments. A contact angle model with pinning and friction leads to close agreement between simulations and drop motion over a bare PDMS layer, particularly in terms of the relevant timescales. When contact line friction is neglected, the fully coupled numerical solution shows a good match with experimentally determined drop movement over a silicone oil-coated PDMS layer. Over both surfaces, continuous motion of the water droplet is seen to be achieved in three stages, namely, initial spreading, acceleration, and attainment of constant speed.

Metallic hierarchical structures uniformly covered with WC@PDMS composite coatings toward comprehensively durable superhydrophobic surfaces

Superhydrophobic surface is one of the most promising materials for the prevention and elimination of ice in daily lives but its durability remains a tremendous problem. Inevitable deterioration on the low-free-energy coating caused by harsh environment restrains their potential applications. Icephobic polymers are more durable than mostly used fluorosilanes for their higher thickness and cohesive strength but difficult to be uniformly modified on rugged micro-nanostructures. In this study, a nanostructured tungsten carbide doped PDMS layer was uniformly covered on aluminum microcones via a hybrid fabrication process combining nanosecond and femtosecond laser ablations and a rotational homogenization process. The prepared superhydrophobic surfaces exhibited excellent water repellency and anti-icing properties in icing-deicing cycles, water flow impacting and freezing-melting cycles. Multiple mechanical/chemical damage tests were performed to test their durability comprehensively. In mechanical tests, the surfaces could withstand linear abrasion length of 240 cm under 5.2 kPa pressure, impacting sand amount of at least 80 g or tape peeling for at least 200 cycles. The chemical durability was elucidated in −40 to 200 °C cycles, 2-day ultraviolet exposure and immersion in different liquids. The proposed hybrid method to form homogenous, ductile and durable superhydrophobic coatings could yield a prospective candidate for applications in anti-fouling and anti-icing.

Capsaicin-based silicone antifouling coating with enhanced interlocking adhesion via SIPN

Silicone-based coatings generally exhibit excellent dynamic fouling release due to their low surface energy and elastic modulus. However, the poor adhesion of these coatings at the interface between the coating and the substrate, as well as deficient static antifouling capabilities, severely deteriorate their antifouling properties over extended periods. Herein, an epoxy-poly(dimethylsiloxane)/capsaicin (EP-PDMS/CAP) coating with highly enhanced interfacial adhesion and remarkable antifouling performances was prepared. The coating adhesion strength of the EP-PDMS/CAP has been improved by more than 5 times compared to a PDMS control coating (from 0.4 MPa to 2.04 MPa) by forming a semi-interpenetrating polymer network (SIPN) structure between the epoxy and PDMS layers. The EP-PDMS/CAP coating achieved the superior antifouling effects in both static and dynamic conditions, the anti-bacterial rate was as high as 96.8 %, and the anti-algal adhesion rate to the green algae Chlorella increased by 95.7 %, due to the synergistic effects of the fouling release performance from the PDMS coating and the fouling prevention of capsaicin. Furthermore, the EP-PDMS/CAP coating was proven to be extremely stable in different treatments such as acid/basic solutions, air oven heating test, and cyclic sand abrasion, showing great potential for anti-biofouling under aggressive conditions. This work provides a promising pathway towards the development of high-performance silicone-based composite coatings for efficient marine anti-biofouling.

A PDMS-Agar Hybrid Microfluidic Device for the Investigation of Chemical-Mechanical Associative Learning Behavior of C. elegans.

Associative learning is a critical survival trait that promotes behavioral plasticity in response to changing environments. Chemosensation and mechanosensation are important sensory modalities that enable animals to gather information about their internal state and external environment. However, there is a limited amount of research on these two modalities. In this paper, a novel PDMS-agar hybrid microfluidic device is proposed for training and analyzing chemical-mechanical associative learning behavior in the nematode Caenorhabditis elegans. The microfluidic device consisted of a bottom agar gel layer and an upper PDMS layer. A chemical concentration gradient was generated on the agar gel layer, and the PDMS layer served to mimic mechanical stimuli. Based on this platform, C. elegans can perform chemical-mechanical associative learning behavior after training. Our findings indicated that the aversive component of training is the primary driver of the observed associative learning behavior. In addition, the results indicated that the neurotransmitter octopamine is involved in regulating this associative learning behavior via the SER-6 receptor. Thus, the microfluidic device provides a highly efficient platform for studying the associative learning behavior of C. elegans, and it may be applied in mutant screening and drug testing.

Wideband THz metamaterial absorber based on unpatterned resistive-sheet and water layers

A metamaterial absorber (MA) based on unpatterned resistive-sheet and water layers is proposed. It can provide wideband absorption with the absorptivity over 90% from 162 GHz to 1.5 THz and the relative bandwidth is high up to 161%. The anti-parallel surface currents between the layers of resistive-sheet and ground metal produce magnetic resonance, which contributes to a portion of the absorption. It is found that the water layer plays a leading role in the broadband strong absorption and the main power loss is concentrated in the water layer, which is mainly attributed to magnetic resonance at the border between water layer and PDMS layer. In addition, the absorber has polarization insensitivity and good stability at wide incident angles. The design of the proposed absorber is validated by the consistency between the simulated and calculated results. This work may provide a simple and time-saving approach to design wideband MAs.

Inner-selective polyethersulfone-polydimethylsiloxane (PES-PDMS) thin film composite hollow fiber membrane for CO2/N2 separation at high pressures

Carbon dioxide (CO2) is the dominant greenhouse gas (GHG) and thus CO2 capture from flue gas of power plants, the main anthropogenic source of emission, is a key approach to mitigating the climate change. Thin-film composite (TFC) membranes have received extensive research attention recently as a promising post-combustion CO2 capture (CO2/N2) technology owing to its energy-efficiency, design versatility and upscaling potential. However, studies with the most industrially relevant membrane configuration, the hollow fibers, are rather limited for this application. Herein, we developed an inner-selective polyethersulfone-polydimethylsiloxane (PES-PDMS) TFC hollow fiber membrane by inner coating PDMS in the lumen of PES hollow fibers and then pressurizing the hollow fibers for CO2/N2 separation. The optimal PES-PDMS TFC membrane can achieve a CO2 permeance of 2150 GPU and a CO2/N2 selectivity of 20 when the operating pressure was between 20–22 bar, which holds good potential for post-combustion CO2 capture. The high separation performance arises from a combination of the stretched PES and PDMS layers. The micro-deformation of both layers under high pressures at the lumen side could possibly reduce the selective layer thickness. It may also induce polymer chain orientation, increase the fractional free volume, and potentially create free volume with smaller sizes, thus enhancing the CO₂ permeability and CO₂/N₂ selectivity from the PDMS and PES layers.

Fabrication of Biomaterial-Based Triboelectric Nanogenerators: Study of the Relationship between Output Performance and Strain in Dielectric Materials

A triboelectric nanogenerator (TENG) collects thriftless mechanical energy from the surrounding environment and transforms it into electrical energy. This work demonstrated a feasible method for metallizing the polylactic acid (PLA) surface, which was subsequently used as a biomaterial-based TENG electrode material. We demonstrated that microcellular holes and hydrophilic groups (−C-OH and −COOH) were introduced on an alkali-treated PLA sheet surface, subsequently used to absorb Pd2+ by means of covalent bonds, which could serve as catalytic centers for the reduction of Ni2+. Of note, the Ni-layer deposition mechanism represents a typical island-like growth pattern. To be precise, a Ni-coated PLA sheet was fabricated successfully and used as a TENG electrode material. The device had excellent performances, with a maximum output voltage of about 5.1 V, obtained from 6% strain (the corresponding stress is 32.4 kPa) on the PDMS layer. Furthermore, it revealed that under a stress of 0.14–32.4 kPa and strain of 1.3–6%, a linear regression relation existed between the output voltage and the dielectric material strain, and it was found that the density of electrostatic charge formed on the TENG material surface is 4.1 × 106 C/m2. Additionally, the as-fabricated TENG equipment was attached to various positions of the human body and lab to demonstrate the electrical energy obtained from the mechanical movement. It was also used for real-time demonstrations as a self-powered body-tracking device application which may be beneficial in tracking human position counters during self-powered and emergency exercise movements.

Silicon-Based 3D Microfluidics for Parallelization of Droplet Generation.

Both the diversity and complexity of microfluidic systems have experienced a tremendous progress over the last decades, enabled by new materials, novel device concepts and innovative fabrication routes. In particular the subfield of high-throughput screening, used for biochemical, genetic and pharmacological samples, has extensively emerged from developments in droplet microfluidics. More recently, new 3D device architectures enabled either by stacking layers of PDMS or by direct 3D-printing have gained enormous attention for applications in chemical synthesis or biomedical assays. While the first microfluidic devices were based on silicon and glass structures, those materials have not yet been significantly expanded towards 3D despite their high chemical compatibility, mechanical strength or mass-production potential. In our work, we present a generic fabrication route based on the implementation of vertical vias and a redistribution layer to create glass-silicon-glass 3D microfluidic structures. It is used to build different droplet-generating devices with several flow-focusing junctions in parallel, all fed from a single source. We study the effect of having several of these junctions in parallel by varying the flow conditions of both the continuous and the dispersed phases. We demonstrate that the generic concept enables an upscaling in the production rate by increasing the number of droplet generators per device without sacrificing the monodispersity of the droplets.

Multifunctional Actuator Based on Graphene/PDMS Composite Materials with Shape Programmable Configuration and High Photothermal Conversion Capability.

Photoresponsive smart actuators based on carbon materials are attracting increasing attention. However, the low content of carbon materials currently limits the development of carbon material actuators. In this work, we designed and prepared a multifunctional bilayer composite actuator with controllable structures and high photothermal conversion efficiency. The actuator consists of a graphene/polydimethylsiloxane (PDMS) composite layer and a PDMS layer. With an ultrahigh graphene mass fraction (30%), the actuator exhibits a good hydrophobicity, unexpectedly high photothermal conversion performance (from room temperature to 120 °C within 1 s), and rapid photo-response capability. By thermal regulation, ultraviolet laser cutting, and assembly, the actuator can achieve shape programmable configuration in three-dimensional directions. Bionic crawling robots achieve a crawling speed of 0.065 mm/s, and liquid tracking robots achieve a rotational motion of 106°/s, a linear motion of 8.42 mm/s, and a complex "W"-shaped trajectory motion. This work provides a simple and effective method for the preparation and realization of multifunctional actuators based on graphene composite materials.

Exploring the water capture efficiency of covalently attached liquid-like surfaces.

The capture of moisture from the atmosphere through condensation has the potential to provide a sustainable source of water. Here, we investigate the condensation of humid air at low subcooling condition (11 °C), similar to conditions for natural dew capture, and explore how water contact angle and contact angle hysteresis affect the rates of water capture. We compare water collection on three families of surfaces: (i) hydrophilic (polyethylene oxide, MPEO) and hydrophobic (polydimethylsiloxane, PDMS) molecularly thin coatings grafted on smooth silicon wafers, which produce slippery covalently attached liquid surfaces (SCALSs), with low contact angle hysteresis (CAH = 6°); (ii) the same coatings grafted on rougher glass, with high CAH (20°-25°); (iii) hydrophilic polymer surfaces [poly(N-vinylpyrrolidone), PNVP] with high CAH (30°). Upon exposure to water, the MPEO SCALS swell, which likely further increases their droplet shedding ability. MPEO and PDMS coatings collect similar volume of water (around 5 l m-2day-1), both when they are SCALS and non-slippery. Both MPEO and PDMS layers collect about 20% more water than PNVP surfaces. We present a basic model showing that, under low heat flux conditions, on all MPEO and PDMS layers, the droplets are so small (600-2000 µm) that there is no/low heat conduction resistance across the droplets, irrespective of the exact value of contact angle and CAH. As the time to first droplet departure is much faster on MPEO SCALS (28min) than on PDMS SCALS (90min), slippery hydrophilic surfaces are preferable in dew collection applications where the collection time frame is limited.