Polydimethylsiloxane Layer Research Articles

Flexible and Durable Conducting Fabric Electrodes for Next-Generation Wearable Supercapacitors.

This study presents the fabrication of highly conducting Au fabric electrodes using a layer-by-layer (LBL) approach and its application toward energy storage. Through the ligand-exchange mechanism, the alternating layers of tris(2-aminoethyl)amine (TREN) and gold nanoparticles (Au NPs) encapsulated with tetraoctylammonium bromide (TOABr) ligands (Au-TOABr) were deposited onto the fabric to achieve a highly conducting Au fabric (0.12 Ω/□) at room temperature in just two LBL cycles. In contrast to several existing techniques, the current study realizes highly conducting Au fabric (7-15 Ω/□) in a layer-by-layer coating. The obtained Au fabrics demonstrate excellent stability against various deformations and abrasions, and its sheet resistance remained unaltered even after multiple cycles of bending, twisting, scotch tape adhesions, and sandpaper abrasions. In addition, the prepared Au fabrics exhibit high robustness toward various chemical media, highlighting their anticorrosive properties. Although Au fabrics showed a slight increase in sheet resistance postwashing and ultrasonication tests, it was got ridden by coating a thin layer of a biocompatible polydimethylsiloxane (PDMS) polymer. Besides enhancing the adhesion of Au NPs, PDMS coating offered a hydrophobic surface to fabrics rendering their use toward self-cleaning applications. High-performing energy storage devices integrated with wearable technologies are in great demand. In this context, here, electropolymerized polyaniline (PANI)-coated Au fabrics were employed to develop supercapacitors with remarkable energy-storing capability. In a symmetric two-electrode configuration, the device offered a maximum areal capacitance of 660 mF/cm2 with high areal energy and power densities of 58.64 μWh/cm2 and 22.86 mW/cm2, respectively. The solid-state supercapacitor device (SSD) fabricated using Au/PANI-30 electrodes exhibited an areal capacitance of 495 mF/cm2 with energy and power densities of 33 μWh/cm2 and 10,660 μW/cm2, respectively. This LBL method offers a significant advantage over existing techniques by offering simple room-temperature fabrication with excellent conductivity and adaptability to various substrates and with ease of scalability.

Ultra-sensitive flexible piezoresistive pressure sensor for biopressure and tiny force measurements based on tilted micropillar array microstructures

Abstract Flexible pressure sensor can acquire important information during contact with the human body and the external environment, thus shining in various fields such as rehabilitative monitoring, artificial intelligence and touch-on displays. With the development of the fifth generation (5 G) mobile communication technology and the Internet of Things, flexible sensing devices need to be used more in ultra-precision fields, such as biopressure and tiny force detection, which require devices to have higher sensitivity. In this work, an ultra-sensitive flexible piezoresistive pressure sensor is created by embedding multi-walled carbon nanotubes onto a polydimethylsiloxane layer with tilted micropillar array microstructures on its surface. Based on the sensing mechanism of microstructure bending deformation rather than compression deformation, the fabricated device exhibits fascinating properties in terms of ultrahigh sensitivity (1.74 kPa−1), fast response time (<100 ms), low detection limit (5.8 Pa) and excellent cyclic stability. Furthermore, the prepared sensors can meet the sensing needs in a variety of dynamic environments, including real-time artery pulse, airflow, acoustic vibrations, and finger bending, indicating that the sensing devices have enormous potential in human health assessment and diagnosis, and robotic tactile perception. This work provides an innovative approach for the development of highly sensitive sensors required in practical applications.

Hierarchical rGO‐Based Triboelectric Sensors Enable Motion Monitoring and Trajectory Tracking

AbstractFlexible sensors are increasingly recognized for their transformative potential in wearable electronic devices, medical monitoring, and human‐computer interaction. Despite the advancements, developing a flexible sensor array with a simple structure and large area preparation for effective signal sensing and monitoring capabilities remains challenging. In this study, a hierarchical rGO‐based flexible triboelectric sensor (HG‐FTS) is scalably prepared by a simple blade‐coating approach, in which the nitrogen‐doped reduced graphene oxide (rGO) sheet is hierarchically deposited in a polydimethylsiloxane (PDMS) layer. The flexible triboelectric sensor performed in single electrode mode not only demonstrates exceptional reliability and consistency but also achieves a maximum voltage of ≈129 V and a power density of ≈0.5 W m−2. These characteristics enable the real‐time monitoring of human physiological signals and joint motion with high fidelity. Furthermore, an intelligent human‐computer interactive control system is developed using the HG‐FTS, featuring a digital array touch screen with a rectangular pattern. The build system can be successfully used for pressure sensing, object shape recognition, and trajectory tracking. This work provides a viable solution to the large area preparation and high‐performance flexible sensor manufacturing and demonstrates the potential application of HG‐FTS in human‐computer interaction, signal monitoring, and intelligent sensing.

A dual-channel SPR sensor based on both sides polished PCF with composite films for wide-range detection of RI and temperature

Abstract A dual-channel surface plasmon resonance (SPR) fiber sensor for detecting the refractive index and temperature has been presented in this paper. The fiber is polished on both sides to form two planes, and on one side, a refractive index measurement channel is formed by coating MoS2 film on the surface of a silver film. On the other side, a polydimethylsiloxane (PDMS) layer is coated on the surface of the silver film as the temperature sensing channel. The results showed that the sensor has a maximum spectral sensitivity of 23000 nm/RIU at a liquid RI of 1.333-1.415 and a maximum spectral sensitivity of 12.3 nm/℃ at a temperature of -20 °C to 90 °C. The results show that this sensor, with high sensitivity and wide-range detection, has important applications in the fields of organic chemistry, modern medicine and environmental detection. It also has a momentous reference significance for the design of SPR sensors that can realize multiparameter sensing.

Optimizing Stretchability and Electrical Stability in Bilayer-Structured Flexible Liquid Metal Composite Electrodes.

Gallium-based liquid metals remain in a liquid state at room temperature and exhibit excellent electrical and thermal conductivities, low viscosity, and low toxicity, making them ideal for creating highly stretchable and conductive composites suitable for flexible electronic devices. Despite these benefits, conventional single-layer liquid metal composites face challenges, such as liquid metal leakage during deformation (e.g., stretching or bending) and limited elongation due to incomplete integration of the liquid metal within the elastomer matrix. To address these limitations, we introduced a bilayer structure into liquid metal composites, comprising a lower polydimethylsiloxane (PDMS) layer and an upper PDMS-liquid metal mixed layer. In the mixed layer, the liquid metal precipitates, forming a conductive network spanning both layers. This bilayer composite structure demonstrated significantly improved stretchability and elongation compared to pure PDMS or single-layer composites. Additionally, by adjusting the size and content of the liquid metal particles, we optimized the composite's mechanical and electrical properties. Under optimal conditions, spherical liquid metal particles deform into elliptical shapes under tensile stress, increasing conductive pathways and reducing electrical resistance. The combined effects of the bilayer structure and particle shape deformation enhanced the composite's stretchability and elongation, supporting its potential for flexible electronics applications.

AI-Aided Gait Analysis with a Wearable Device Featuring a Hydrogel Sensor.

Wearable devices have revolutionized real-time health monitoring, yet challenges persist in enhancing their flexibility, weight, and accuracy. This paper presents the development of a wearable device employing a conductive polyacrylamide-lithium chloride-MXene (PLM) hydrogel sensor, an electronic circuit, and artificial intelligence (AI) for gait monitoring. The PLM sensor includes tribo-negative polydimethylsiloxane (PDMS) and tribo-positive polyurethane (PU) layers, exhibiting extraordinary stretchability (317% strain) and durability (1000 cycles) while consistently delivering stable electrical signals. The wearable device weighs just 23 g and is strategically affixed to a knee brace, harnessing mechanical energy generated during knee motion which is converted into electrical signals. These signals are digitized and then analyzed using a one-dimensional (1D) convolutional neural network (CNN), achieving an impressive accuracy of 100% for the classification of four distinct gait patterns: standing, walking, jogging, and running. The wearable device demonstrates the potential for lightweight and energy-efficient sensing combined with AI analysis for advanced biomechanical monitoring in sports and healthcare applications.

Nanocellulose‐Based Interfacial Solar Evaporator: Integrating Sustainable Materials and Micro‐/Nano‐Architectures for Solar Desalination

AbstractClean‐water harvesting through solar interfacial evaporation technology has recently emerged as a strategy for resolving global water scarcity. In this study, rapid carbon‐dioxide‐laser‐induced carbonization and facile ice‐templating is employed to construct a cellulose‐based solar evaporator bearing a hybrid multi‐layer micro‐/nano‐architecture (i.e., a laser‐induced carbon (LC) nanostructure and a cellulose aerogel (CA) nano/microstructure). The LC exhibits a light‐absorbing/photothermal nanoporous carbon structure that offers high light absorption and multiple light scattering. Additionally, the CA exhibits numerous nanopores and unidirectional microchannels that facilitate rapid water transport via capillary action. This hybrid LC/CA micro‐/nano‐architecture enabled rapid vapor generation with an average water evaporation rate (ν) of 1.62 kg m−2 h−1 and an evaporation efficiency (η) of 66.6%. To further enhance the evaporation performance, a polydimethylsiloxane (PDMS) layer is coated onto the side of the LC/CA evaporator to increase its floatability in the simulated water; ν and η of the PDMS‐coated LC/CA evaporator (LC/CA/PDMS) increased to 1.9 kg m−2 h−1 and 83.8%, respectively. Additionally, the LC/CA/PDMS evaporator exhibited a high ν value of 1.68 kg m−2 h−1 in simulated seawater, originating from excellent resistance to salt accumulation via its self‐cleaning ability. Furthermore, the solar evaporator exhibited scalability for fabrication as well as biodegradable properties.

SERS-Based Microfluidic Bioscreening Platform for Selective Detection of β-Amyloid Peptides.

This study reports development of a microfluidic device for highly sensitive and selective detection of a β-amyloid peptide (Aβ1-42) in simulated cerebrospinal fluid, using surface-enhanced Raman spectroscopy (SERS). The device ensemble comprises a purine ligand (Pu) and its interaction with silver nanoparticles (AgNPs) to generate SERS hotspots. The low surface energy of the synthesized Pu ligand and high surface energy of AgNPs are utilized for the functionalization and formation of a Pu-AgNP SERS substrate. We have integrated a novel polydimethylsiloxane (PDMS) microfluidic device with Pu-AgNPs using a combination of photo- and soft lithography fabrication, sealed by thermal cross-linking with another layer of PDMS, to produce an effective screening platform for Aβ1-42. The SERS spectrum from the microfluidic device affords almost noise-free measurements, with excellent limit-of-detection values.

Arrays of Bowl-Shaped Janus Particle Film with Structured Colors.

Structural colors generated via total internal reflection (TIR) using nanostructure-free micro-concave shapes have garnered increasing attention. However, the application of large micro-concave structures for structural coloration remains limited. Herein, a flexibly tunable structural color film fabricated by casting polydimethylsiloxane (PDMS) on an array of large poly(glycidyl methacrylate) (PGMA) bowl-shaped particles is reported. The resultant film exhibits tunable red to green structural colors with changing observation angles. Moreover, the color can be further tailored by altering the shape of the film itself. The incorporation of the PDMS layer not only facilitates a shift in the locus of TIR from the bottom surface to the top concave surface of the particles, thereby enabling the generation of structural color, but also confers enhanced flexibility to the film. Further decoration with silver nanoparticles imparts antimicrobial properties, yielding a novel antimicrobial coating material with structural colors. The simple and cost-effective strategy for the production of structural color films provides potential applications in antimicrobial coatings, enabling accessible and customizable structural coloration using big-size micro-concave particles.

A Flexible Organomagnetic Single-Layer Composite Film with Built-In Multistimuli Responsivity.

Materials possessing multiple properties and functionalities, that can be controlled or modulated by external stimuli, are a central focus of current research in materials sciences due to their potential to significantly enhance various future technological applications. Herein, we report a significant advancement in this field through the development of a smart, multifunctional organomagnetic composite material. By utilizing a thin layer of polydimethylsiloxane (PDMS) and polypyrrole (PPy) precursors, doped with nickel nanoparticles (NiNPs), we have created an innovative organomagnetic, PDMS/PPy/NiNPs (PPN), single-layer composite film that displays multistimuli responsivity. The study presents the first demonstration of a multifunctional flexible, three-component film structure integrating the structural and flexible PDMS component, together with a conductive polymer component and metal-based nanoparticles into a single-layer design, which displays enhanced and unprecedented responsivity properties against multiple different stimuli. Unlike typical stacked multilayered structures, that exhibit one or two functionalities at most, this novel configuration exhibits multiple functionalities, including magnetoresistance, mechanical stress response, piezoresistivity, and temperature change sensitivity. The as-prepared film demonstrates notable magnetoresistance responsivity, with a relative electrical resistance, ΔR/R0, changing under a weak magnetic field and under ambient conditions. The significance of our study lies in the film's versatility, stability, and sensitivity, especially within the physiological temperature range, making it highly relevant for future biomedical applications. Furthemore, the film's sensitivity to mechanical deformation reveals an impressive piezoresistance behavior. Unlike existing multilayer architectures of higher complexity, our single-layer thin film offers a simpler, more flexible, and reliable solution with a broad range of stimuli-sensing capabilities. The significance of this novel multiresponsive composite material is underscored by the growing demand for advanced materials in biomedical devices, magnetic switches, sensors, electronic skin, transistors, and organic spintronic devices. These promising organomagnetic self-standing layers provide a robust platform for future technological innovations.

Nanograting-assisted flexible Triboelectric Nanogenerator for active human motion detection

This manuscript presents the development of a nanograting assisted Triboelectric Nanogenerator (TENG) for improved performance. The TENG leverages a cost-effective and straightforward fabrication method, utilizing nano-gratings on a Polydimethylsiloxane (PDMS) layer to enhance the triboelectric effect. The device characteristics are evaluated by considering tapping force, separation distance, and load resistance. The experimental electrical characterization shows that the output voltage increases significantly with higher applied forces, with a 2N force generating voltage increases of over 584% compared to a 0.1N force. Conversely, the output voltage decreases as the separation distance is reduced. The charge storage capability of the proposed device is demonstrated by integrating a TENG with a full-wave bridge rectifier. Furthermore, the fabricated TENG demonstrates remarkable sensitivity in detecting various body motions. When strategically placed on the biceps, the TENG effectively tracks muscle contraction and expansion with a voltage range of +0.5V to -1V, exhibiting a sensitivity of 1.5V per cycle. Similarly, the TENG accurately detects bending movements in the knee and elbow joints. For knee bending, the voltage output ranges from +2.5V to -1V, resulting in a sensitivity of 3.5V per cycle. Elbow flexion generates voltages between +4V and -5V, corresponding to a sensitivity of 9V per cycle. This clear correlation between voltage and specific body movements makes the TENG a promising candidate for wearable health and motion monitoring systems.

Sustainable rewritable paper based on photoresponsive tungsten oxide quantum dots for anti-counterfeiting and waterproofing

Ink-free printing using photochromic paper has emerged as a promising technology for information recording, transmission, and secure interaction applications. Tungsten oxide quantum dots (WO3 QDs), with their rapid UV response, excellent photochemical stability, and outstanding fatigue resistance, exhibit significant potential as an ink-free medium in the construction of sustainable rewritable paper. However, challenges such as low binding force, poor stability, and weak scalability limit the development of reversible photochromic paper based on WO3. In this study, a novel sustainable rewritable paper based on a scalable strategy of covalent modification and hydrophobic layer protection has been reported. Specifically, cellulose papers modified with silane coupling agent were directly grafted with amino-modified WO3 QDs by covalent bonding through the addition reaction between epoxy and amine groups. Subsequently, the sustainable rewritable paper was obtained by the deposition of hydrophobic layer of polydimethylsiloxane (PDMS) via a dip-coating method. The rewritable paper exhibits exceptional properties, including high color contrast, extended color-retention (over 21 days), good rewritability (20 cycles) and excellent resistance to water or stains. Based on ink-free writing technology, the photo-responsive rewritable papers were utilized for anti-counterfeiting and encryption or decryption, demonstrating their great potential for information recording, storage, and security protection.

Temperature self-compensated dual core fiber-optic sensor integrated with moisture sensitive MIL-96(Al) film for breath detection

In this paper, a dual-core fiber optic sensor has been proposed for dynamic monitoring of temperature and humidity. The side core is polished into a D-type optical fiber, and a layer of nano-silver film and a layer of polydimethylsiloxane (PDMS) are deposited to construct a surface plasmon resonance (SPR) temperature compensator. The middle core is constructed as the long-period fiber grating (LPFG) sensing channel. The mode conversion of LPFG is achieved by TiO2 film, and its refractive index (RI) sensitivity is increased by about 4 times. Meanwhile, a layer of moisture sensitive MIL-96(Al) film is grown outside the TiO2 film. Due to the particular pore structure for water molecules, it is possible to change the effective RI of MIL-96(Al) film by absorbing water molecules. Research has shown that the LPFG sensor can achieve a relative humidity sensitivity of −0.411 nm/%RH. Finally, the sensor successfully achieved real-time dynamic monitoring of respiratory rate.

Multiplexed Microfluidic Platform for Parallel Bacterial Chemotaxis Assays.

The sensing of and response to ambient chemical gradients by microorganisms via chemotaxis regulates many microbial processes fundamental to ecosystem function, human health, and disease. Microfluidics has emerged as an indispensable tool for the study of microbial chemotaxis, enabling precise, robust, and reproducible control of spatiotemporal chemical conditions. Previous techniques include combining laminar flow patterning and stop-flow diffusion to produce quasi-steady chemical gradients to directly probe single-cell responses or loading micro-wells to entice and ensnare chemotactic bacteria in quasi-steady chemical conditions. Such microfluidic approaches exemplify a trade-off between high spatiotemporal resolution of cell behavior and high-throughput screening of concentration-specific chemotactic responses. However, both aspects are necessary to disentangle how a diverse range of chemical compounds and concentrations mediate microbial processes such as nutrient uptake, reproduction, and chemorepulsion from toxins. Here, we present a protocol for the multiplexed chemotaxis device (MCD), a parallelized microfluidic platform for efficient, high-throughput, and high-resolution chemotaxis screening of swimming microbes across a range of chemical concentrations. The first layer of the two-layer polydimethylsiloxane (PDMS) device comprises a serial dilution network designed to produce five logarithmically diluted chemostimulus concentrations plus a control from a single chemical solution input. Laminar flow in the second device layer brings a cell suspension and buffer solution into contact with the chemostimuli solutions in each of six separate chemotaxis assays, in which microbial responses are imaged simultaneously over time. The MCD is produced via standard photography and soft lithography techniques and provides robust,repeatable chemostimulus concentrations across each assay in the device. This microfluidic platform provides a chemotaxis assay that blends high-throughput screening approaches with single-cell resolution to achieve a more comprehensive understanding of chemotaxis-mediated microbial processes. Key features • Microchannel master molds are fabricated using photolithography techniques in a clean room with a mask aligner to fabricate multilevel feature heights. • The microfluidic device is fabricated from PDMS using standard soft lithography replica molding from the master molds. • The resulting microchannel requires a one-time calibration of the driving inlet pressures, after which devices from the same master molds have robust performance. • The microfluidic platform is optimized and tested for measuring chemotaxis of swimming prokaryotes.

Rapid, non-contact identification of organic solvents: Monolithic GaN chips incorporating PDMS/PS photonic crystals

The prompt identification of organic solvents is essential in many practical scenarios. This work introduces a compact optical device for rapid, non-contact detection of organic solvents. The fabrication of the GaN chip employs a monolithic integration approach, enabling the simultaneous formation of on-chip components responsible for light emission and light detection. The self-assembled polystyrene (PS) spheres embedded in a polydimethylsiloxane (PDMS) layer as photonic crystals can effectively induce distinct optical changes when exposed to organic solvents. By analyzing the magnitude and recovery time of the photocurrent signals, up to seven types of organic samples can be distinguished. Different from traditional optical sensing systems, the proposed chip-level integration strategy eliminates the need for external assembly of optical components, resulting in an ultracompact millimeter-sized sensing unit. The developed device also offers features of simplicity of use and a short measurement time of less than 10 s, making it a feasible solution for quick detection in emergency scenarios.

Photo-isomerization enabled reversible wavelength switching in fiber random laser for color image encryption.

Random lasers owing the functionality of generating random spectra facilitate the chaotic encrypted systems essential for cryptography in the current information epoch. Nevertheless, single wavelength bands of random lasers provide an unsuitable key for image encryption that causes outline interpretation and a fragile complex dual chaotic encryption demanding secured image encryption. This research presents an inevitable development of a reversible switchable wavelength fiber random laser composed of the mixture of highly polarized intramolecular charge transfer dye molecules and the optimum concentration of titanium dioxide acting as gain and efficient scattering mediums respectively within a polyvinyl alcohol matrix. This mixture with a certain ratio is coated on a fiber employing a dip coated method, followed by a layer of polydimethylsiloxane to facilitate with high coefficient of thermal expansion. Random laser emission is enabled with dynamically switchable wavelengths obeying the excited state intramolecular proton transfer phenomenon under the photo-isomerization. The optimum scatters concentration yields a lower threshold of 32 µJ/cm2 with full width at half maximum of 0.4 nm and dual emission reversible switchable wavelength bands centered around 443 nm and 464 nm attributed to inter charge transfer feature of the dye molecules. Thereby, the dual reversible switchable wavelength bands feed as input for a dual chaotic color image encryption system. Further, in this integrated system, beam divergence of random laser emissions remains less than 20° during both situations of with- and without irradiation. This delicate approach paves the way in laying the foundation about the applicability of fiber random lasers in an information security system.

One-step fabrication of multifunctional superhydrophobic copper surfaces via laser-assisted ablation PDMS solution

The super-hydrophobic surfaces have been greatly restricted in multi-functional applications because of the poor surface durability and multi-step processes such as preparing rough structures and low surface energy modification. In this work, a multifunctional wear-resistant super-hydrophobic surface (SHS) was primarily developed by one step laser etching polydimethylsiloxane (PDMS) i.e. the uncured PDMS layer was laser-ablated just after it was coated on the surface of copper. The wettability, morphology and chemical composition of the surfaces were characterized by a contact Angle measuring instrument, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR). The results show that the developed SHS has the high contact angle (WCA) of 156.8° and low sliding angle (WSA) of 4.6°; which presents a regular linear grating array and a large number of coral-like rough structures, and the developed SHS can withstand at least 120 tape stripping tests, 40 sandpaper friction abrasion tests, 60 h of high temperature treatment (100 °C∼300 °C) or 240 h of ultraviolet light exposure tests, respectively. The self-cleaning rate and anti-fouling rate of the SHS were 94.2 % and 91.8 %, respectively, and the freezing time of droplets on the SHS is 162 s longer than that on the original copper surface, and almost 3 times longer than that on the smooth surface. In all, the non-polluting wear-resistant multifunctional SHS was primarily developed by laser ablation of metals and polymers, which has strong potential usage in the fields of anti-fouling of industrial pipeline systems and anti-icing of outdoor power transmission systems.

Four-wave mixing temperature sensor based on graphene oxide-coated microfiber hybrid waveguide

Utilizing a hybrid waveguide comprising microfiber and graphene oxide (GO), this study introduced an innovative temperature sensor based on four-wave mixing (FWM) effect. The methodology involved a tunable continuous wave (TCW) laser and a self-engineered all-fiber mode-locked laser operating at 1560 nm. The microfiber, featuring a minimum diameter of 10 μm, was fabricated through the flame fusion tapering technique, and the microfiber surface was coated with a GO film through the spontaneous evaporation of a GO solution. To improve the stability and robustness of the sensor, a layer of polydimethylsiloxane (PDMS) was applied to the surface as a protective coating. The GO film compensated for dispersion in conjunction with microfiber, enhanced nonlinearity and facilitated low-power FWM phenomena. Furthermore, it increased temperature sensing sensitivity. By measuring the center wavelength shift of the idler and signal light, we achieved a temperature sensing sensitivity of −2.08 nm/℃ from −15 ℃ to 20 ℃ using the CW laser at 1540 nm. This sensor also had a resolution of 0.024 ℃, a response time of 0.12 s and a maximum temporal resolution of 0.08 s. Our study marks the initial investigation of a temperature sensing mechanism employing the FWM phenomenon within this unique hybrid waveguide. It serves as a proof of concept for using a microfiber combined with the two-dimensional material GO film to generate nonlinear FWM for temperature sensing. Continuous optimization of experimental conditions and waveguide dimensions is expected to enhance sensing performance. This opens up new avenues for future research in novel optical sensing technology, particularly in the exploration of high-performance sensors through the integration of nonlinear phenomena with different two-dimensional materials, showcasing substantial research potential.

Preparation of brittle ITO microstructures using Laser-Induced forward transfer technology

The performance of transparent conductive microstructures plays a significant role in determining the device efficiency. The fabrication of ITO microstructures on the flexible optoelectronic devices remains challenging because of the high-temperature processing requirements and brittleness of the ceramic material. This paper highlights a three-dimensional microfabrication technique that combines sacrificial layer etching and laser-induced transfer. By studying the donor material thickness and the laser energy density, control of the sacrificial layer transfer thrust was achieved to yield an optimal microstructure performance. Different shapes of ITO transparent conductive microstructures were fabricated on polydimethylsiloxane (PDMS) surfaces, demonstrating structural integrity, visible light transmittances > 90 %, and resistivities of ≤ 8 × 10−4 Ω·cm. Finite element analysis was employed to simulate the impact transfer of the donor material onto the receiving substrate, thereby elucidating the energy-absorbing protective role of the flexible PDMS layer. Effective control of the transfer force was identified as a crucial factor in achieving the successful transfer of brittle films. This high-precision and rapid array processing approach meets the demands of automated batch manufacturing, indicating its potential for use in patterned processing on flexible substrates, as an alternative to lithographic techniques. This technique could be applied in the preparation of electronic skins and flexible devices. Additionally, for the first time, a 3 × 3 pixel resistive array sensor was integrated on a Ag nanowires/PDMS surface, demonstrating array pressure-sensing capabilities at pressures of 0–80 kPa. This study represents a significant step towards the development of multifunctional flexible optoelectronic devices.

A highly sensitive temperature sensor based on long period fiber grating coated with polymer-bilayer-membrane

This study introduces a highly sensitive temperature sensor based on long-period fiber grating (LPFG). The sensor is composed of a long period fiber grating covered by a higher RI (RI) layer of polyvinyl alcohol (PVA) and a lower RI layer of polydimethylsiloxane (PDMS). The PVA layer enables the sensor to operate in the mode transition region with high sensitivity, and the PDMS layer further enhances the temperature sensitivity owing to its high thermos-optic coefficient. In addition, the sensor can mitigate the influence of humidity due to the hydrophobic properties of PDMS. Experimental results show that the temperature sensitivity can achieve to 1232.3 pm/℃ within the range of 20℃-100℃ for an LPFG with a period of 363 μm coated with a 265 nm PVA layer and a 20 μm PDMS layer.