Polydimethylsiloxane Research Articles

Rod-type handheld hybrid nanogenerator for mechanical energy harvesting and self-powered speed sensing applications

Nanogenerators offer a promising solution for converting mechanical movements into electricity with significant implications for portable electronics. Herein, we propose a novel approach using magnesium (Mg)-doped zinc oxide (ZMO) nanoflakes (NFs) embedded in polydimethylsiloxane (PDMS) composite films, which serve as the negative tribo-layer in a triboelectric/piezoelectric hybrid nanogenerator (HNG) operating in contact-separation mode. The ZMO NFs, with an optimized Mg concentration for a high dielectric constant, are mixed into PDMS, and their concentration is further optimized to achieve the highest electrical output from the HNG. The optimized device generates a voltage, current, and power density of approximately 186 V, 5.23 μA, and 1.56 W/m2, respectively while also exhibiting high stability. The electricity generated by this HNG is successfully utilized to power commercial portable electronics. To further enhance its practicality, six similar HNGs were fabricated and integrated into a 3D printed structure, forming a rod-type handheld HNG (RTH-HNG). The energy-harvesting capability of the RTH-HNG is systematically investigated under applied external forces. Additionally, the speed-sensing ability of the RTH-HNG during hand-shaking motions is assessed, with the system demonstrating an accuracy of up to 94 % when compared to a commercially available infrared sensor. Moreover, the real-time vibrational energy harvesting capability of the RTH-HNG was demonstrated by attaching it to a bicycle. Therefore, the proposed RTH-HNG can function not only as a mechanical energy harvester for powering small portable electronics but also as a self-sufficient speed sensor for various real-time applications.

Flexible AgNW/PDMS nanocomposite for strain and pressure sensing

This study presents the fabrication and characterization of an ultra-thin (<1 mm) piezoresistive sensor based on a silver nanowire (AgNW) and polydimethylsiloxane (PDMS) nanocomposite, capable of simultaneous strain and pressure sensing. The sensor exhibits high sensitivity, detecting strains as low as 0.5 % with a range of up to 40 %, demonstrates frequency responsiveness from 0.5 to 3 Hz, and maintains functionality over 1000 cycles. The sensor’s performance was evaluated through cyclic tensile and compressive tests. We hypothesize that the compression sensing mechanism is a consequence of the Poisson effect in the PDMS substrate, where transverse compression induces axial strains parallel to the AgNW network, causing disconnections within the nanowire matrix. The sensor’s versatility was demonstrated through various biofeedback applications, including finger bending, applied pressure, calf raises, and elbow flexion. With its thin profile and dual-mode sensing capability, this AgNW/PDMS nanocomposite sensor shows promise for biomechanics, sports science, and healthcare monitoring applications.

Anti-corrosion superhydrophobic micro-GF/micro-TiB2/nano-SiO2 based coating with braid strengthening structure fabricated by a single-step spray deposition

Superhydrophobic surfaces with self-cleaning, anti-biofouling and corrosion resistance merits are attractive for applications in major engineering fields. Generally, these surfaces possess low-surface-energy chemistry and micro- or nanoscale surface roughness. However, rough surfaces are fragile and highly susceptible to abrasion for high local pressures under mechanical load, causing loss of superhydrophobicity. In this study, we proposed a "fiber weaving/hard particles embedding-soft membrane" strategy to construct a kind of organic-inorganic composite coating by embedding micro-glass fiber (GF)/micro-TiB2/nano-SiO2 particles into the polydimethylsiloxane (PDMS)@polyurethane (PU) for fabricating robust superhydrophobic coating. The addition of micro-nano ceramic particles plays two roles including "hard" micro-skeletons to overcome vulnerable issue of "soft" organic membrane and creation of wear-resistant bearing points on the surface. Furthermore, "soft" membrane can absorb stress when subjected to external mechanical force and PU serves as an adhesive to improve interfacial bond strength. Additionally, GF intersperses in the coating, providing anchoring effect and PDMS serves as a modifier to decrease surface energy. Consequently, the proposed hybrid coating could simultaneously augment its mechanical robustness and multifunctional performance, breaking the notorious "trade-off" restriction of superhydrophobic coating. The preparation parameters and operation condition on the performance of the coating were investigated systematacially. The optimized superhydrophobic coating exhibits the highest water contact angle (WCA) of 167.3° ± 3.9°, the lowest sliding angle (SA) of 4.6° ± 1.3°, corrosion protection efficiency of 95.7 % in 3.5 wt% NaCl solution, with exceptional self-cleaning, anti-pollution, adaptability to various substrates, thermostable, anti-icing and mechanical stability properties, among the top-tier multifunctional performance. The inherent properties of micro-glass fiber, micro-TiB2 and nano-SiO2 ceramics and their highly ordered arrangement in the superhydrophobic coating are expected to provide an effective and versatile design proposal for potential applications in corrosion protection.

Development of a flexible strain sensor for monitoring human activities based on 3D MXene microspheres and 1D CNTs

Resistive strain sensors, which possess simple preparation, stability, and reliability features, are particularly advantageous compared to other sensor types. Here, a flexible resistance sensor designed to monitor human activities is assembled using designed three-dimensional (3D) MXene microspheres (FM@MXene) and one-dimensional (1D) CNTs in a polydimethylsiloxane (PDMS) system. The sensor exhibits a sensitivity of 5.59 and a response time of ∼330 ms, with reasonable good durability (> 200 cycles).

Leveraging anchoring ligands for efficient one-pot solvothermal synthesis of PDMS functionalized iron oxide polymer nanocomposites (PNC’s)

Producing substantial quantities of high purity, narrow size distribution, magnetic polymer nanocomposites (PNC’s) has been a challenge for the nanoparticle synthesis community. In this study, we introduce a novel one-pot solvothermal synthesis technique to produce a type of PNC known as a ferrofluid. By employing a polymer (polydimethylsiloxane (PDMS)) modified with anchoring ligands as the surfactant, we eliminate the need for a post-synthesis ligand exchange, resulting in high yield and purity of the final product. This approach offers greater flexibility in polymer selection and simplifies the synthetic process. Electron microscopy, magnetic characterization, infrared spectroscopy, and thermal analysis were employed to investigate particle size, crystallinity, magnetic behavior, and surface environment. Our findings suggest that this new synthetic technique could significantly advance the development of magnetic nanoparticle-based theranostics.

Effects of stamp material and restoration depth on the accuracy of direct composite resin restorations using stamp technique

ObjectivesTo evaluate the effects of different stamp materials and restoration depths on the accuracy of direct composite resin restorations using stamp technique. MethodsEighty standard resin teeth were divided into four groups based on different stamp materials: flowable composite resin (FR), vinyl polydimethyl siloxane (VPS) for bite registration (VB), VPS for impression (VI) and transparent VPS (TV). Each material group was further divided into two subgroups based on restoration depth (1 and 2 mm; n = 10). Standardized Class I cavities were prepared and restored with the corresponding stamps. Pre- and post-treatment scans of each tooth were fitted using Geomagic Control X software, generating deviation distribution maps of the occlusal surface. The accuracy indicators, including mean height variation (MHV), root mean square (RMS), and proportions of height variation with different ranges (PHVrange), were recorded to evaluate the accuracy of restorations. Analysis of variance (ANOVA) were used for statistical analysis (α=0.05). ResultsThe type of stamp material significantly affected all accuracy indicators, while restoration depth did not show a significant effect on any of the indicators. MHV values ranged from 29.70 ± 5.88 μm to 63.52 ± 9.58 μm, and RMS values ranged from 62.78 ± 8.76 μm to 101.79 ± 13.17 μm, displaying a trend of FR<VB<VI<TV. The FR groups had the highest PHV<0.05mm values (72.24 ± 3.40 % for 1 mm, 71.47 ± 8.54 % for 2 mm) and the lowest PHV>0.2mm values (0.70 ± 0.50 % for 1 mm, 0.94 ± 0.47 % for 2 mm). In contrast, the TV groups exhibited the lowest PHV<0.05mm values (59.69 ± 10.23 % for 1 mm, 59.67 ± 5.70 % for 2 mm), while the VI groups showed the highest PHV>0.2mm values (7.34 ± 1.58 % for 1 mm, 8.20 ± 3.16 % for 2 mm). ConclusionsThe accuracy of direct composite resin restorations using stamp made of flowable composite resin was higher than that of all tested VPS materials, thereby reducing the need for occlusal adjustment and improving clinical efficiency. Besides, restoration depth had no significant impact on the accuracy of stamp technique, regardless of the stamp material used. Clinical significanceThe accuracy of direct composite resin restorations using stamp technique with different stamp materials varies. The flowable composite resin stamp exhibits higher accuracy compared with VPS stamps, reducing the need for occlusal adjustments.

Triboelectric Nanogenerators Based on Transition Metal Carbo-Chalcogenide (Nb2S2C and Ta2S2C) for Energy Harvesting and Self-Powered Sensing.

With burgeoning considerations over energy issues and carbon emissions, energy harvesting devices such as triboelectric nanogenerators (TENGs) are developed to provide renewable and sustainable power. Enhancing electric output and other properties of TENGs during operation is the focus of research. Herein, two species (Nb2S2C and Ta2S2C) of a new family of 2D materials, Transition Metal Carbo-Chalcogenides (TMCCs), are first employed to develop TENGs with doping into Polydimethylsiloxane (PDMS). Compared with control samples, these two TMCC-based TENGs exhibit higher electric properties owing to the enhanced permittivity of PDMS composite, and the best performance is achieved at a concentration of 3wt. ‰ with open circuit voltage (Voc) of 112V, short circuit current (Isc) of 8.6µA and charge transfer (Qsc) of 175nC for Nb2S2C based TENG, and Voc of 127V, Isc of 9.6µA, and Qsc of 230nC for Ta2S2C based TENGs. These two TENGs show a maximum power density of 1360 and 911mWm-2 respectively. Moreover, the tribology performance is also evaluated with the same materials, revealing that the Ta2S2C/PDMS composite as the electronegative material presented a lower coefficient of friction (COF) than the Nb2S2C/PDMS composite. Their applications for energy harvesting and self-powered sensing are also demonstrated.

EDA Fibronectin Microarchitecture and YAP Translocation During Wound Closure.

Fibronectin (Fn) is an extracellular matrix glycoprotein with mechanosensitive structure-function. EDA Fn, a Fn isoform, is not present in adult tissue but is required for tissue repair. Curiously, EDA Fn is linked to both regenerative and fibrotic tissue repair. Given that Fn mechanoregulates cell behavior, Fn EDA organization during wound closure might play a role in mediating these differing responses. One mechanism by which cells sense and respond to their microenvironment is by activating a transcriptional co-activator, Yes-associated protein (YAP). Interestingly, YAP activity is not only required for wound closure, but similarly linked to both regenerative and fibrotic repair. Therefore, this study aims to evaluate how, during normal and fibrotic wound closure, EDA Fn organization might modulate YAP translocation by culturing human dermal fibroblasts on polydimethylsiloxane (PDMS) substrates mimicking normal (soft: 18 kPa) and fibrotic (stiff: 146 kPa) wounded skin. On stiffer substrates mimicking fibrotic wounds, fibroblasts assembled an aligned EDA Fn matrix comprising thinner fibers, suggesting increased microenvironmental tension. To evaluate if cell binding to the EDA domain of Fn was essential to overall matrix organization, fibroblasts were treated with Irigenin, which inhibits binding to the EDA domain within Fn. Blocking adhesion to EDA led to randomly organized EDA Fn matrices with thicker fibers, suggesting reduced microenvironmental tension even during fibrotic wound closure. To evaluate if YAP signaling plays a role in EDA Fn organization, fibroblasts were treated with CA3, which suppresses YAP activity in a dose-dependent manner. Treatment with CA3 also led to randomly organized EDA Fn matrices with thicker fibers, suggesting a potential connected mechanism of reducing tension during fibrotic wound closure. Next, YAP activity was assessed to evaluate the impact of EDA Fn organization. Interestingly, fibroblasts migrating on softer substrates mimicking normal wounds increased YAP activity but on stiffer substrates, decreased YAP activity. When fibroblasts on stiffer substrates were treated with Irigenin or CA3, fibroblasts increased YAP activity. These results suggest there may be disrupted signaling between EDA Fn organization and YAP translocation during fibrotic wound closure that could be restored when reestablishing normal EDA Fn matrix organization to instead drive regenerative wound repair.

Simultaneous Triboelectric and Mechanoluminescence Sensing Toward Self‐Powered Applications

AbstractSimultaneous phenomena of triboelectricity and mechanoluminescence (ML) acquire vital insights into the mechanics of charge separation and recombination, as well as the relationship between mechanical stress and light emission. In the present work, polydimethylsiloxane (PDMS) and ZnS:Cu particle‐based composites are fabricated, which have good ML characteristics and can generate electricity via contact electrification. ML, in conjunction with a triboelectric nanogenerator (TENG), contributes by producing power from mechanical operations while also giving vital visual input in the form of light emission. This dual capability improves user awareness and efficiency in a variety of applications, making mechanical systems and wearable devices easier to monitor and optimize. To accomplish this, a single‐electrode mode silver (Ag) nanowires embedded PDMS‐ZnS: Cu‐based TENG device is developed and achieved an electrical output of 60 V, 395 nA, and 15 nC by using a linear motor. Furthermore, the combined ML and TENG device is employed in various cases of safety monitoring. This integration provides self‐powered devices that detect mechanical stress, delivering real‐time warnings and illumination signals for increased safety and communication in demanding conditions such as SOS signaling, underwater driving, deep mining, and sports.

Wearable nitric oxide-releasing antibacterial insert for preventing device-associated infections

Medical device-associated infections are a pervasive global healthcare concern, often leading to severe complications. Bacterial biofilms that form on indwelling medical devices, such as catheters, are significant contributors to infections like bloodstream and urinary tract infections. This study addresses the challenge of biofilms on medical devices by introducing a portable antimicrobial catheter insert (PACI) designed to be efficient, biocompatible, and anti-infective. The PACI utilizes nitric oxide (NO), known for its potent antimicrobial properties, to deter bacterial adhesion and biofilm formation. To achieve this, a photoinitiated NO donor, S-nitroso-N-acetylpenicillamine (SNAP), is covalently linked to a polydimethylsiloxane (PDMS) polymer. This design allows for higher NO loading for long-term impact and prevents premature donor leaching, a common challenge with SNAP-blended polymers. The SNAP-PDMS material was applied to a side-glowing fiber optic and connected to a wearable light module emitting 450 nm light, creating a functional antimicrobial insert. Activation of the fiber optic, accomplished with a one-click mechanism, enables real-time NO release, maintaining controlled NO levels for a minimum of 24 hours. The therapeutic levels of NO released via photocatalysis from the PACI demonstrated remarkable efficacy, with >90 % reduction in bacterial viability against S. aureus, S. epidermidis, and P. mirabilis without any cytotoxic impact on mammalian cells. This study underscores the potential of the NO-releasing insert in clinical settings, providing a portable and adaptable solution for preventing catheter-associated infections.

Flexible Porous Ag2Se Films: From Freestanding Inorganic Films to Inorganic‐Network/Organic‐Skeleton Thermoelectric Generators

AbstractSilver selenide (Ag2Se) flexible films are promising near‐room‐temperature thermoelectric candidates for low‐grade heat harvesting. However, existing Ag2Se films are generally attached on substrates, which impedes further flexibility improvement of the films and constrains the scenarios of applications. Here a cost‐effective and scalable strategy is presented, which combines screen printing and annealing, for synthesizing freestanding Ag2Se inorganic films with different densities of pores. High‐density pores and thin thickness endow the films with high flexibility, while films with low‐density pores obtain higher power factor. Furthermore, by utilizing the porous microstructure, a composite structure consisting of a Ag2Se conductive network and an organic polydimethylsiloxane (PDMS) skeleton is fabricated, which further improves films’ stability under bending and torsion. Finally, a flexible thermoelectric generator comprising five Ag2Se/PDMS legs and encapsulated PDMS outputs a voltage of 20.2 mV and a maximum power of 810 nW (the corresponding power density is 5.4 W m−2) at a temperature difference of 30 K, verifying potential application at near room temperature. This work offers a useful paradigm for fabricating substrate‐free Ag2Se porous films with high flexibility for near‐room‐temperature thermoelectric applications.

Photofunctional gold nanocluster-based nanocomposite coating for enhancing anti-biofouling and anti-icing properties of flexible films

Elastomeric materials have garnered significant attention across biomedical and industrial fields. Multifunctionality and environmental stability are essential requirements for the application of these materials. Herein, we developed photofunctional gold nanocluster-based nanocomposites (SiO2-AuNC) and coated them on elastomeric polydimethylsiloxane (PDMS) films through one-step way to enhance anti-biofouling and anti-icing properties. The SiO2-AuNC coating, created by immobilizing ultra-small gold nanoclusters (AuNCs) onto hydrophobic silica nanoparticles surface using a gel-sol method, forms an island-like convex structure. The immobilization significantly enhanced radiative transitions and promoted the generation of reactive oxygen species of AuNCs, which provided robust anti-biofouling property through photosensitization to the films. Meanwhile, the rigid SiO2-AuNC nanocomposite markedly enhances the wear resistance of the films. Additionally, the hierarchical micro- and nanostructure of SiO2-AuNC coating increases the hydrophobicity of the films, effectively preventing the aggregation of supercooled water droplets, thereby providing superior and durably anti-icing properties. This one-step coating provides a simple and effective strategy for multifunctional surface modification with nanoparticles, showing potential biomedical and industrial applications.

Construction of a superhydrophobic surface with long-term durability on 5052 Aluminium for corrosion protection

Superhydrophobic surfaces have been demonstrated to offer exceptional corrosion protection for metal surfaces. However, long-term stability issues have plagued superhydrophobic surfaces. In this study, a durable superhydrophobic surface on aluminum (SHC-Al) was created using etching combined with anodizing followed by polydimethylsiloxane (PDMS) modification. To optimize the multi-scale rough structures, the optimal anodizing conditions were explored in detail. The superhydrophobic surfaces were analyzed using Field emission scanning electron microscopy (FESEM), Confocal laser microscopy (CLSM), X-ray energy spectrometry (EDS), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle (CA) measurements, stability tests, and electrochemical analysis. The results reveal the successful preparation of a nest-like micro-nano composite structure on metal surface, and the contact and sliding angles of SHC-Al were measured at 157.6° and 6°, demonstrating the formation of excellent superhydrophobic surface. Electrochemical tests showed a corrosion current density of only 1.38 × 10–9 A∙cm-2 for SHC-Al, with a corrosion inhibition efficiency of 99.97 %, highlighting its outstanding anti-corrosion performance. Furthermore, stability tests demonstrated the SHC-Al surface had long-term durability. This study not only provides new evidence for the preparation of long-lasting superhydrophobic surfaces, but also provides a new solution for the practical application of superhydrophobic surfaces.

Dynamic electromechanical characterizations of poly(vinylidene fluoride) based nanocomposite films on ultra‐low modulus polymer substrate

AbstractThis article explores the electromechanical performance of poly(vinylidene fluoride) (PVDF) films with silver nanoplatelets on smooth polydimethylsiloxane (PDMS) substrates. PVDF, a semi‐crystalline polymer, shows piezoelectric properties when processed at low temperatures, making it ideal for energy harvesting and sensors. This research addresses a gap by examining high strain rate and complex electromechanical characteristions of PVDF composites, which are underexplored. Films, fabricated using a non‐vacuum rod coating method, underwent dynamic electromechanical tests (strain rate ~ 2 s−1), including stretching, twisting, combined stretching and twisting, and forced vibrations. Results show the films function up to 17% applied strain with a gage factor of 10.57. In twisting tests, the laminates perform up to 387° in slow twisting (gage factor = 28.34) and 341° in fast twisting (gage factor = 7.65). Combined stretching and twisting tests show performance decreases, with functionality up to 6.24% strain at a twist angle of 330.1°. Vibration tests reveal that increased amplitude reduces performance, with the laminates enduring frequencies between 4.35 and 12.14 Hz. The films also exhibit a linear piezoelectric response, with a maximum open circuit voltage of 37.2 V under an impact load of 1112 N, underscoring the potential of PVDF/Ag nanocomposites for advanced MEMS applications.

Arc-shaped air layer bioinspired by ginkgo nut to resist high humidity environment for PET fabrics

Developing simple processes and significant effect modification method for polyester (PET) fabrics to resist hygrothermal aging is a formidable challenge. In this study, inspired by the silver mirror phenomenon of natural ginkgo nut, we utilized the pea pod-shaped nanoparticles that zinc oxide (ZnO) was encapsulated in polyhedral oligomeric silsesquioxane (ZnO@POSS), and polydimethylsiloxane (PDMS) to construct stabilized arc-shaped air layer on the PET fabric surface to resist high humidity environment. The round belly structures of pea pod-shaped ZnO@POSS and interlaced physical networks assisted by PDMS on the PET fabrics surface served as the crucial roles to capture and retain air, resulting in the capacity of the arc-shaped air layer was significantly larger than other microstructures underwater. The water vapor was prevented from entering the fabric interstices that the self-catalytic hydrolysis behavior of PET macromolecular chains was efficiently restrained, and the strength retention of PET fabric was significantly improved from 45 % to 89 % after accelerated hygrothermal aging test (60 °C, 80 % RH, 600 h). This work represents a simple and effective approach to improve the durability for PET fabrics in high humidity environments.

Reliable plasmonic biosensing with atmospheric pressure dielectric barrier discharge oxygen plasma treated polydimethylsiloxane microfluidic channels

Polydimethylsiloxane (PDMS) has emerged as a popular choice of material for many microfluidic and flexible sensing devices despite its inherent hydrophobic nature. Here, we report on the use of atmospheric pressure dielectric barrier discharge (APDBD) oxygen (O2) plasma in the development of hydrophilic and protein repulsive PDMS microchannels for plasmonic sensing application. The effect of plasma treatment on the wettability, surface energy and hydrophilicity retention capacity of PDMS was determined using contact angle measurements. The PDMS sample exposed to low-power DBD O2 plasma for 6 min demonstrated lowest contact angle of 35.15˚, surface energy of 62.83 mN/m and hydrophilicity retention capacity of more than 50 days in Phosphate Buffered Saline (PBS). The treatment of PDMS with plasma induces surface hydrophilicity due to the introduction of polar functional groups as evinced by Fourier Transform Infrared (FTIR) analysis without compromising the bulk structure and optical properties of PDMS which were confirmed by X-Ray Diffraction (XRD) and Ultraviolet-visible (UV-Vis) Spectroscopic measurements. The plasma treated PDMS was used in the construction of a microfluidic Surface Plasmon Resonance (SPR) biosensor which demonstrated very low detection limits of 7.13 ng/ml, 5.91 ng/ml and 1.47 ng/ml and high sensitivities of 16.8˚/(µg/ml), 13.5˚/(µg/ml) and 16.65˚/(µg/ml) against anti-Human Immunoglobulin-G protein raised in mouse, goat and rabbit respectively. The obtained results infer that APDBD O2 plasma is a promising technique to render PDMS hydrophilic suited for reliable microfluidic based plasmonic biosensing applications.

An optical fiber high sensitivity temperature sensor with MZI and FPI parallel connection

Accurate detection of temperature is of great significance in the field of medical research. The focal point of this article centers around an optical fiber sensor that integrates Fabry Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS) and Mach Zehnder interferometer (MZI), leveraging the principle of the vernier effect. By introducing the vernier effect principle, the sensitivity is 31.09 nm/°C in the detection range of 36 ∼ 40°C, and the maximum temperature measurement error is about 0.55 %. In addition, good linear response and longtime stability make it suitable for application in various scenarios where accurate temperature measurement is required.

Three-dimensional free-standing heterostructures out of MoS2 and rGO with infused PDMS towards electromechanical pressure sensing

Abstract The behavior of two-dimensional (2D) materials constructed as three-dimensional structures is studied to bring such materials one step closer to the real-life application. Lattices structures of gyroid triply periodic minimal surface (TPMS) were fabricated out of 2D materials, namely, molybdenum disulfide (MoS2), and reduced graphene oxide (rGO), forming for the first time free-standing MoS2 (FSM) lattice and free-standing hetero-structural lattice of MoS2 and rGO (FSH) out of TPMS. These 2D materials were also integrated with polydimethylsiloxane (PDMS) elastomer, forming FSM/PDMS and FSH/PDMS composites. Mechanical characterization, including compression and cyclic tests, were conducted on FSM, FSH, and the composites. Additionally, electromechanical characterization was conducted to evaluate the sensing potential of these structures. It is worth noting that the elastic modulus of the 10 unit-cells with either FSM or FSH was higher than the other lattices of the same type. FSH tends to have a higher modulus at 1504.4 kPa in the 10 unit-cells. This modulus is even higher at 3 MPa when PDMS is added to the FSH lattice. Due to the brittle fracture, FSM or FSH lattices follow the layer-by-layer failure mechanism. Samples with PDMS are more stable towards such cyclic tests without noticeable failures or a decrease in elastic modulus. Finally, the 10 unit-cell lattices of FSH/PDMS composite have the highest conductivity at 2.5 mA, and a comparable sensitivity at 0.365 kPa−1 over the range of 0–100 kPa.

High sensitivity gas pressure and temperature optical sensors based on tapered no-core fiber coated with polydimethylsiloxane (PDMS)

This article introduces a novel high-sensitivity pressure and temperature sensor utilizing a tapered no-core fiber (NCF) structure created by splicing the NCF with a single-mode fiber (SMF) to form a “SMF-NCF-SMF” structure, tapering the NCF, and applying a polydimethylsiloxane (PDMS) film on the tapered NCF surface. The experimental results show that the device with a diameter of 10 μm has a pressure sensitivity of 86.63 nm/MPa within one to two atmospheres. Furthermore, the temperature sensitivity is −1.97 nm/°C from 30 °C to 60 °C. The sensor exhibits excellent stability and repeatability, and the PDMS film enhances the mechanical strength of the device, indicating promising potential for high-sensitivity pressure and temperature applications.

Apple leaf-inspired bilayered Janus wood evaporator with decoupled light-vapor interfaces for high-efficiency solar steam generation

Solar-driven interfacial evaporation technology provides a facile and promising strategy for producing clean water from seawater. Wood-based evaporators have recently been extensively explored for solar desalination due to the structural merits and sustainability of natural wood. However, the light absorption and water evaporation functions are commonly integrated at the same surface for a traditional wood-based solar evaporator, which definitely causes mutual interference between the incident sunlight and the generated vapor leading to inevitable energy loss. Herein, inspired by the unidirectional transpiration of hypostomatic apple leaves, a bilayered Janus wood evaporator with decoupled light absorption and water evaporation surfaces was subtly engineered to avoid the sunlight-vapor interference for efficient solar evaporation. The bilayered evaporator consists of a longitudinal wood piece as the water transport layer and a carbonized transverse wood piece infiltrated with polydimethylsiloxane (PDMS) as the photothermal layer. The hydrophilic longitudinal piece with vertically aligned channels can continuously wick water to the evaporation surface, while the hydrophobic transverse piece with horizontal channels enables efficient heat transfer given its high thermal conductivity. Thanks to the unique bilayered configuration, the developed evaporator demonstrates an excellent evaporation rate of 2.12 kg m−2 h−1 with an evaporation efficiency of 92.3 % (1 sun), surpassing most of the traditional wood-based evaporators. Moreover, the bilayered evaporator exhibits good salt resistance and can effectively purify diverse wastewaters including organic dye solutions and oil–water emulsions. This Janus-interface structural design provides a novel strategy for developing high-performance solar evaporator toward clean water production.