Simple Dip-coating Technique Research Articles

Mussel-inspired, fully biobased, mechanically robust, and room temperature healable supramolecular elastomer composites for sustainable strain sensors

The sustainable development of strain sensors necessitates the use of mechanically robust and self-healing elastomers derived from biobased feedstocks to ensure durability, extend service life, and reduce reliance on fossil resources. Herein, we report mussel-inspired, fully biobased, mechanically robust, room-temperature healable supramolecular elastomer composites (SECs) fabricated from natural rubber (NR), polydopamine (PDA), and cellulose nanofiber (CNF). Hydrogen bonds were formed among the hydroxyl and secondary amine groups of PDA, hydroxyl groups of CNF, and the non-rubber components of NR, resulting in room-temperature self-healing and mechanically reinforced NR/PDA/CNF SECs. The SECs achieved a tensile strength of up to 9.5 MPa and recovered over 80% of its strength after self-healing at room temperature for 3 h. The robust adhesion properties of PDA within the SECs enabled the surface coating of the SECs with conductive carbon nanotubes (CNT) to fabricate flexible strain sensors without additional adhesives through a simple dip-coating technique. These flexible strain sensors exhibited excellent structural stability, high sensitivity, and reliability, making them suitable for human motion signal detection. This study underscores the potential of biobased and self-healing elastomers in enhancing the performance and sustainability of flexible strain sensors, contributing significantly to the development of sustainable and durable sensing technologies.

Fabrication of SiO2/TiO2 coated polyethylene films with photoinduced superhydrophilicity, antifogging property and mechanical robustness

Anatase type TiO2 has garnered significant attention due to its potent oxidation capacity, stability, photoinduced superhydrophilicity and self-cleaning performance. However, there are few reports on the preparation of robust TiO2 films on substrates with a low glass transition temperature. In this work, SiO2/TiO2 films were fabricated on PE substrates using a simple dip-coating technique. The coated PE films exhibited a maximum transmittance of 86 % and an average transmittance of 85 % in the visible region. The composite films demonstrated remarkable photoinduced superhydrophilicity, antifogging characteristics, and excellent photocatalytic performance. The film showed superhydrophilicity under UV light or xenon lamp illumination, and remained superhydrophilicity after it was placed outdoors for 310 days. In addition, the prepared films also had excellent mechanical properties, and their superhydrophilicity remained unaffected even after 200 cycles of bending, 80 cycles of rolling, and 50 mL water impact test. The preparation method may open a new avenue to the application of TiO2 films on many substrates that are vulnerable to high temperature processes.

Robust Transparent Photothermal Omniphobic Coating for Efficient Anti/Deicing and Antifogging.

Icing and fogging on optical material surfaces bring various problems in daily life. Recently, some photothermal coatings have been reported to prevent the condensation or freeze of water droplets by increasing the surface temperature. However, it is a great challenge to apply them in practical conditions due to their opaqueness and poor mechanical wear-resistant property. In this work, we constructed a robust transparent photothermal omniphobic coating with a simple dip-coating technique. In the coating system, photothermal polypyrrole nanoparticles are introduced into inorganic silica networks, and then polydimethylsiloxane (PDMS) brushes were grafted on the inorganic silica layer to endow the surface with omniphobicity and stain resistance. The transparency and photothermal capacity of the coating can be regulated by the deposition times of the coating. In addition, the coating has an excellent anti/deicing property and reduces ice adhesion obviously due to the existence of "liquid-like" PDMS brushes. More importantly, the coating presents outstanding mechanical wear-resistant and self-lubricating properties that can endure several thousand friction cycles without performance loss. The mechanically robust photothermal omniphobic coating gives a feasible approach to anti-icing and antifogging of transparent substrates under sunlight irradiation.

Highly-sensitive wearable pressure sensor based on AgNWs/MXene/non-woven fabric

Nowadays, wearable medical devices are getting more and more public attention. As a continuous monitoring device in wearable medical devices, flexible pressure sensors have also attracted much attention in the field of wearable electronics. High sensitivity and long-term durability in a wide linear range are key requirements for making reliable and flexible wearable pressure sensors. Here, a comfortable, flexible, environmentally friendly and wearable non-woven fabric is proposed as a substrate for the pressure sensor. Conductive AgNWs/MXene/non-woven fabric is prepared by a simple dip-coating technique and then an overall sandwich structure is formed between two layers of polydimethylsiloxane (PDMS) film and an Interdigitated Array of Electrodes (IDE). The viscose fibres in nonwovens are rich in hydroxyl groups and their hydrophilicity is more conducive to the attachment of conductive MXene nanosheets to the entangled fibre network of nonwovens. The synergistic effect between Ti3C2Tx and AgNWs, and the unique intercalation structure can build a more effective conductive network. The pressure sensor based on AgNWs/MXene/non-woven fabric has a fibrous entanglement structure and a special sandwich structure of the sensor with high sensitivity (0.25–5 kPa pressure range: 14.28 kPa−1), and have a wide sensing range (0.25–400 kPa), rapid response and recovery times (60 ms/120 ms), excellent stability, and long term durability for use in human motion detection applications. In addition, the wearable pressure sensors was used to detect and discriminate between different signals related to human health, including monitoring human movement and breathing, and 4 × 4 arrays was used to detect stress distribution signals. These results suggest that the sensor can be potentially applied in mobile medical monitoring devices, showing broad potential in a new generation of wearable electronic devices.

Eco-friendly functional cellulose paper as a fire alarming via wireless warning transmission for indoor fireproofing

Herein, a strategy for fabricating wallpaper-based smart fire-warning systems to monitor and mitigate indoor fires is proposed. The fire-warning system, based on eco-friendly cellulose paper (CP), is produced via a simple dip-coating technique and provides flexibility, rapid low-temperature warning, and novel local and remote wireless signal conversion capability. Specifically, this fire-warning system can balance flexibility and flame retardancy, reducing the negative impact on the mechanical properties after adding flame retardants. Furthermore, the proposed fire-warning system meets the critical requirement of a fast low-temperature warning, showing warning messages within 2 s under 250 ºC, decreasing the response temperature below the combustion temperature of common materials (＞300 ºC). Moreover, the luminosity and temperature data collected can be sent to local and remote computers by wireless conversion. This work gives insight into the new generation of low-temperature smart fire-warning systems, including the contribution of wireless warning signal transmission to achieve smart and efficient fire detection.

Facile preparation of flame-retardant cellulose composite with biodegradable and water resistant properties for electronic device applications

The aim of the present study is to produce flexible, flame-retardant, water-resistant and biodegradable composite materials. The ultimate goal of this research is to develop simple processes for the production of bio-based materials capable of replacing non-degradable substrates in printed circuit board. Cellulose was chosen as a renewable resource, and dissolved in 1-ethyl-3-methylimidazolium acetate ionic liquid to prepare a cellulosic continuous film. Since flame retardancy is an important criterion for electronic device applications and cellulose is naturally flammable, we incorporated ammonium polyphosphate (APP) as a flame-retardant filler to increase the flame retardancy of the produced materials. The developed material achieved a UL-94 HB rating in the flammability test, while the cellulose sample without APP failed the test. Two hydrophobic agents, ethyl 2-cyanoacrylate and trichloro(octadecyl)silane were applied by a simple dip-coating technique to impart hydrophobicity to the cellulose-APP composites. Dynamic mechanical analysis indicated that the mechanical properties of the cellulosic materials were not significantly affected by the addition of APP or the hydrophobic agents. Moreover, the biodegradability of the cellulosic materials containing APP increased owing to the presence of the cellulase enzyme. The hydrophobic coating slightly decreased the biodegradability of cellulose-APP, but it was still higher than that of pure cellulose film.

Conductive fabrics based on carbon nanotube/Ti3C2Tx MXene/polyaniline/liquid metal quaternary composites with improved performance of EMI shielding and joule heating

Developing lightweight, flexible, conductive electromagnetic interference (EMI) shielding textiles with highly thermal conductivity and Joule heating performance is of great urgency in the field of next generation of wearable electronics, thermal management, communication, and artificial intelligence. In this work, an effective strategy to construct conductive fabrics based on carbon nanotube (CNT)/Ti3C2Tx MXene/polyaniline (PANI)/liquid metal (LM) quaternary composite with improved performance of EMI shielding and Joule heating is proposed. Conductive fabrics decorated with CNT/Ti3C2Tx/PANI/LM (CTPLM) as the conductive slurry by a simple solution dip-coating technique demonstrate a remarkable EMI shielding efficiency (EMI SE) of 78.9 dB at the thickness of 0.27 mm as well as absorbing shielding effectiveness (SEA) of 64.4 dB in the range of 8.2–12.4 GHz. The synergistic effect of high electrical conductivity and porous structure endow CTPLM-CF textiles with significantly higher EMI SE than pristine MXene film and pure CNT layer. Moreover, EMI shielding performance can be further improved to 104.3 dB when three layer conductive fabrics are combined. At the same time, conductive textiles present superior Joule heating performance with a saturation temperature of 34.5 °C @1V, 94.3 °C @2V, and 130.2 °C @3 V after 60 s, respectively. The combination of these components could comprehensively utilize the low density of carbon materials and excellent electrical conductivity from MXene and LM, thus providing a lightweight, flexible, multifunctional conductive textiles with superior EMI shielding and efficient Joule heating capability, which is highly desired for applications in aerospace, intelligent electronics, wearable electronics, thermotherapy, and personal self-heating system in harsh environment.

Green flame-retardant coatings based on iron alginate for polyester fabrics: Thermal stability, flame retardancy and mechanical properties

Polyester (PET) fabrics are widely used in our daily life, but they burn and drip quickly when they encounter flames, and the dripping can cause secondary damage to human bodies. In this study, flame-retardant finishing of PET fabrics was performed by preparing alginate coatings modified with Fe3+. A simple dip-coating technique was used and sodium alginate solution was employed to submerge PET fabrics, after that the coatings were complexed with Fe3+ to endow the flame retardancy of PET fabrics. The micromorphology, mechanical properties, thermal stability, flame retardancy, and burning behaviors of the coated PET fabrics were analyzed. Coated PET fabrics had a limiting oxygen index value of 29%. The vertical flame test illustrated that PET/Iron alginate-2 exhibited excellent self-extinguishing behaviors, no drips appeared. The peak heat release rate of PET/Iron alginate-2 was reduced by 70.3%. In the warp directions, compared with the control, the tensile strength of coated PET textiles increased dramatically. In a word, it is a green method to improve the flame retardancy and anti-dripping of PET fabrics.

A Review of Electro Conductive Textiles Utilizing the Dip-Coating Technique: Their Functionality, Durability and Sustainability.

The presented review summarizes recent studies in the field of electro conductive textiles as an essential part of lightweight and flexible textile-based electronics (so called e-textiles), with the main focus on a relatively simple and low-cost dip-coating technique that can easily be integrated into an existing textile finishing plant. Herein, numerous electro conductive compounds are discussed, including intrinsically conductive polymers, carbon-based materials, metal, and metal-based nanomaterials, as well as their combinations, with their advantages and drawbacks in contributing to the sectors of healthcare, military, security, fitness, entertainment, environmental, and fashion, for applications such as energy harvesting, energy storage, real-time health and human motion monitoring, personal thermal management, Electromagnetic Interference (EMI) shielding, wireless communication, light emitting, tracking, etc. The greatest challenge is related to the wash and wear durability of the conductive compounds and their unreduced performance during the textiles' lifetimes, which includes the action of water, high temperature, detergents, mechanical forces, repeated bending, rubbing, sweat, etc. Besides electrical conductivity, the applied compounds also influence the physical-mechanical, optical, morphological, and comfort properties of textiles, depending on the type and concentration of the compound, the number of applied layers, the process parameters, as well as additional protective coatings. Finally, the sustainability and end-of-life of e-textiles are critically discussed in terms of the circular economy and eco-design, since these aspects are mainly neglected, although e-textile' waste could become a huge problem in the future when their mass production starts.

Durable and covalently attached antibacterial coating based on post-crosslinked maleic anhydride copolymer with long-lasting performance

Clinical application of silicone rubber often encounters challenges. Here a strategy of free radical polymerization with 2-ethylhexyl acrylate (2-EHA) and maleic anhydride (MAh) to introduce durable crosslinked antimicrobial coating that covalently attached on silicone rubber substrate. The 2-EHA and MAh component endow the copolymer with good flexibility and further functionalization respectively. The copolymer coating is covalently bonded to the amine functionalized silicone rubber surface using a simple dip-coating technique and the thickness is adjustable. Poly (hexamethylene biguanide) (PHMB) is covalently coupled on the coating under mild conditions, and the immobilization density of PHMB is up to 3 mg cm−2. The coating layer crosslinked by 1,4-butanediamine gas to enhance the durability of the coating and inhibit undesired swelling and remains intact after 500 bending cycles. The modified substrate exhibits excellent antibacterial activity, with 99.9 % and 95.1 % inhibition rate towards S. aureus and E. coli, respectively. It still maintained 96.2 % of inhibition activity even after 12-day-long culturing with bacteria in simulated urine environment, exhibiting excellent long-term antibacterial stability. The results show that a simple, universal and scalable method to introduce antibacterial properties on polymer substrates, which also provides a new idea for the preparation of flexible cross-linking layers.

Structural characteristics and opto-electrical properties of in-situ synthesized polyaniline films

In the present study, polyaniline (PAni) thin films have been deposited on glass substrates by in-situ chemical polymerization method using simple dip-coating technique and their opto-electrical properties have been studied. The structure of deposited films have been analysed with Fourier transform infrared (FTIR) and Raman spectroscopic techniques to investigate the effect of deposition times on the conjugation length, polaron/bipolaron concentrations and other molecular structure conformations. FTIR and Raman spectroscopy studies reveal increase in both the conjugation length and the polaron/bipolaron carrier concentration with increasing deposition time of the prepared PAni films. The optical properties and optical band-gap of the deposited films have been estimated through UV–visible spectroscopy. The optical band-gap of the deposited films has been found to decrease from 3.31 eV to 3.13 eV with increase in deposition time from 1.5 h to 2.5 h, and further it has been increased slightly to 3.19 eV for the PAni film deposited for 3 h. The electrical conductivity of the deposited films has been found to increase with decrease in optical band gap. The parameters estimated from FTIR, Raman, UV–visible spectroscopy and electrical measurements are in good agreement with each other. It has been observed that the optical and electrical properties of the deposited films depend on the conjugation length of PAni. The polymerization time of 2.5 h has been found to be optimum for obtaining PAni thin films with good electrical conductivity and low optical band gap.

Fluoropolymer-based hybrid superhydrophobic nanocomposite coating with antifouling and self-cleaning properties for efficient oil/water separation

The production of industrial and domestic effluents possessing oily contaminated water has become a global concern as a result of environmental contamination and pollution. Newly synthesized organic-inorganic hybrid nanocomposites with special wetting and anti-wetting properties have been adopted in recent times to address this problem. However, this method has faced a few setbacks in curbing the situation, which leaves the problem persistent. In order to realize the full potential of hybrid composites in combating oil/water contamination, we synthesize a robust organic-inorganic superhydrophobic hybrid nanocomposite containing Polyvinylidene fluoride (PVDF) and silicon hydroxide (SiO2) to coat cellulose filter paper for effective and efficient separation of oil/water mixtures. With a simple dip-coating technique, the superhydrophobic hybrid composite obtain a superhydrophobicity with a water contact angle as high as 161˚ on the filter paper. The coated membrane possessed a robust mechanical property as well as chemical stability which withstands a sandpaper abrasion test of up to 80 cycles and could retain its superhydrophobicity in acidic, neutral and alkaline media after 24hrs of immersion respectively. Moreover, the coated surface possessed nanopores which allows it to be used in oil water separation applications both under pressure and gravity with a separation efficiency of up to 99.7 % and can also be recycled many times for use. The excellent antifouling and self-cleaning ability of the coated membrane also prevents the adhesion of contaminants from the surface. The outstanding performance of the facilely and cost-effective fabricated superhydrophobic hybrid composite reveals a great potential for curbing the problems of oil contamination while addressing some existing barriers to the full potential realization of hybrid composites.

Scalable Fabrication of Conjugated Microporous Polymer Sponges for Efficient Solar Steam Generation.

Seawater evaporation realized by solar-thermal conversion represents one of the most sustainable and effective strategies to obtain fresh water. Many approaches have been proposed to achieve high efficiencies of solar-thermal conversion, but their practical applications are limited by the low scalability. Herein, novel porphyrin/aniline-based conjugated microporous polymers (PACMPs) are synthesized via a Buchwald-Hartwig coupling reaction, which are then integrated with polyurethane sponges via a simple dip-coating technique. The PACMP-modified sponges (PACSs) retain the high porosity of the sponge substrate and excellent solar-thermal conversion properties of PACMPs. Under standard solar irradiation (1 kW m-2), PACSs achieve a high seawater evaporation rate of 1.31 kg m-2 h-1 with a solar-thermal conversion efficiency of 86.3%. PACSs show no salt accumulation and high performance of desalination and dye decolorization, removing >99.9% salt and >99.2% dye, respectively. The self-floating characteristic, recyclability, and durable solar-thermal evaporation efficiencies enable PACSs to be promising candidate materials for seawater desalination and sewage purification.

Chitosan-metal oxide nanoparticle hybrids in developing bi-functional polyamide 66 textiles with enhanced flame retardancy and wettability

Polyamide textiles with multi-functional properties have received a huge attention in the technical textile field due to their excellent physical properties; however, their easy ignition and relatively hydrophobic nature quench their potential application. Thus, in this work, bi-functional polyamide 66 (PA66) textiles with improved flame retardant and wettability properties were developed using metal-oxide nanoparticles, namely TiO2 and SiO2 in the presence of chitosan (CS) in a simple dip-coating technique. The application of TiO2 and SiO2 nanoparticles with CS escalated the limiting oxygen index (LOI) value up to 23.5% along with a significant reduction in the peak heat release rate (pHRR) by 31%. In line, an enhanced level of wettability was achieved as a much lowered water contact angle value of 10˚ was realized. In sum, such finishing was found to be a semi-durable one in the laundering test with a slight deterioration in the handle and tensile properties.

A hybrid approach of surface and direct absorption of solar radiation on parabolic solar collector.

This paper presents a novel approach of utilizing a spectrally selective coating inside the absorber tube of a solar parabolic collector for enhanced photothermal conversion. The photothermal performance of a hybrid system that incorporates an internal coating and nanofluid is analyzed in the present work. The internal coating developed is a composite of PMMA/CuO/Epoxy and as applied using the simple dip-coating technique. The maximum weighted solar absorptance of the internal coating was found to be 57.51%. The significance and interactions of the coating process variables, like concentrations of PMMA and CuO and the number of dips, were analyzed using the central composite design (CCD) of response surface methodology (RSM). An optimized coating (Concentration of PMMA and CuO: 4997.7 and 170.8 mg/30 ml, Number of Dips: 4) was arrived at based on the desirability function. Prior to the introduction of internal coating on the parabolic solar collector, a lab-scale photothermal conversion study was carried out using the optimized internal coating. The results revealed the superior performance of the internal coating when compared with that of pure surface absorption and direct absorption. Finally, the optimized internal coating was incorporated in a parabolic collector, with CuO nanofluid as a working fluid. Maximum efficiency of 62.80% was obtained for the hybrid system the internal coating and CuO nanofluid, compared to 31.6% for a direct absorption solar collector.

Influence of Calcium Silicate and Hydrophobic Agent Coatings on Thermal, Water Barrier, Mechanical and Biodegradation Properties of Cellulose.

Thin films of cellulose and cellulose–CaSiO3 composites were prepared using 1-ethyl-3-methylimidazolium acetate (EMIMAc) as the dissolution medium and the composites were regenerated from an anti-solvent. The surface hydrophilicity of the resultant cellulose composites was lowered by coating them with three different hydrophobizing agents, specifically, trichloro(octadecyl)silane (TOS), ethyl 2-cyanoacrylate (E2CA) and octadecylphosphonic acid (ODPA), using a simple dip-coating technique. The prepared materials were subjected to flame retardancy, water barrier, thermal, mechanical and biodegradation properties analyses. The addition of CaSiO3 into the cellulose increased the degradation temperature and flame retardant properties of the cellulose. The water barrier property of cellulose–CaSiO3 composites under long term water exposure completely depends on the nature of the hydrophobic agents used for the surface modification process. All of the cellulose composites behaved mechanically as a pure elastic material with a glassy state from room temperature to 250 °C, and from 20% to 70% relative humidity (RH). The presence of the CaSiO3 filler had no effect on the elastic modulus, but it seemed to increase after the TOS surface treatment. Biodegradability of the cellulose was evaluated by enzyme treatments and the influence of CaSiO3 and hydrophobic agents was also derived.

Nature-Inspired Hierarchical Protrusion Structure Construction for Washable and Wear-Resistant Superhydrophobic Textiles with Self-Cleaning Ability.

The use of toxic components and short longevity greatly restricted the commercial application of superhydrophobic surfaces in oil-water separation, antifouling, and self-cleaning. To address these concerns, a durable, robust, and fluorine-free superhydrophobic fabric is prepared on account of inspiration of nature. In this work, submicrometer-sized silica particles with different particle sizes are deposited onto cotton fabrics, followed by hydrophobic modification of poly(dimethylsiloxane) (PDMS), and consequently bonded the substrate and coating via powerful covalent bonds through a simple dip-coating technique. The rough surface with an imitated lotus-leaf-like hierarchical protrusion structure is constructed by deposited submicrometer-sized particles with different particle sizes, while the fabric with a low surface energy is achieved by the hydrophobic modification of PDMS. Ultimately, the fabricated fabric exhibits extraordinary superhydrophobicity with a high water contact angle (WCA) of 161° and a small sliding hysteresis angle (SHA) of 2.4°. Besides, considerable mechanical stability to withstand 130 sandpaper abrasion cycles and 40 washing cycles, and chemical resistance with sustained superhydrophobic property in various harsh environments (e.g., boiling water, strong acid/base solutions, and various organic solvents), are presented. Moreover, higher than 90% separation efficiency with a contact angle >150 ° is produced even after 50 cycles when the fabricated fabric serves as a filter during the oil-water separation besides its outstanding staining resistance and self-cleaning property.

Conductive MXene/cotton fabric based pressure sensor with both high sensitivity and wide sensing range for human motion detection and E-skin

• Conductive MXene coated cotton fabric is prepared for wearable pressure sensor. • The pressure sensor shows both high sensitivity and broad sensing range. • The porous and sandwiched architecture accounts for the good sensing property. • The pressure sensor has great potential for human motion detection and E-skin. Flexible wearable pressure sensors have attracted tremendous interest for applications in human health monitoring, electronic skin, artificial intelligence and so on. However, it is still a critical challenge for pressure sensors to simultaneously achieve high sensitivity and wide sensing range while performing well in response time, stability, reliability and wearing comfortability. Here, conductive MXene/cotton fabric was fabricated using the simple dip-coating technique and then sandwiched between polydimethylsiloxane film and an interdigitated electrode for flexible wearable piezoresistive pressure sensor. The abundant hydroxyl groups of cotton fabric and functional groups of MXene were beneficial for the good adhesion of conductive MXene nanosheets onto the entangled fiber networks, constructing effective conductive network. Taking advantage of the excellent flexibility and three-dimensional porous structure of cotton fabric and the special sandwich architecture of the sensor, the MXene/cotton fabric (MCF) based pressure sensor exhibited high sensitivity (5.30 kPa −1 in the pressure range of 0–1.30 kPa), broad sensing range (0–160 kPa), rapid response/recovery time (50 ms/20 ms), excellent stability and long-term durability. Moreover, the MCF based pressure sensor can be employed to detect and distinguish various human health signals, including finger motion, early stage Parkinson’s static tremor and wrist pulse. Importantly, E-skin was also designed based on the MCF based pressure sensor for the recognition of different tactile stimuli, exhibiting promising potential in next generation wearable electronics.

Boosting the Heat Dissipation Performance of Graphene/Polyimide Flexible Carbon Film via Enhanced Through-Plane Conductivity of 3D Hybridized Structure.

The development of materials with efficient heat dissipation capability has become essential for next-generation integrated electronics and flexible smart devices. Here, a 3D hybridized carbon film with graphene nanowrinkles and microhinge structures by a simple solution dip-coating technique using graphene oxide (GO) on polyimide (PI) skeletons, followed by high-temperature annealing, is constructed. Such a design provides this graphitized GO/PI (g-GO/PI) film with superflexibility and ultrahigh thermal conductivity in the through-plane (150 ± 7 W m-1 K-1 ) and in-plane (1428 ± 64 W m-1 K-1 ) directions. Its superior thermal management capability compared with aluminum foil is also revealed by proving its benefit as a thermal interface material. More importantly, by coupling the hypermetallic thermal conductivity in two directions, a novel type of carbon film origami heat sink is proposed and demonstrated, outperforming copper foil in terms of heat extraction and heat transfer for high-power devices. The hypermetallic heat dissipation performance of g-GO/PI carbon film not only shows its promising application as an emerging thermal management material, but also provides a facile and feasible route for the design of next-generation heat dissipation components for high-power flexible smart devices.

Fiber optic Fabry–Perot interferometer sensor: an efficient and fast approach for ammonia gas sensing

In this work, we propose and demonstrate a Fabry–Perot-interferometer-based polydimethylsiloxane (PDMS) and poly(methyl methacrylate) (PMMA)-composite-coated optical sensor for ammonia and volatile organic compounds (VOCs) detection at room temperature. The principle of sensing is based on change in the cavity length of the FP cavity in the presence of varied concentrations of gases, which results in changes in the total reflectance due to the shift in wavelength of an interference pattern. The sensing composite material was coated on a single-mode optical fiber by using a simple dip-coating technique and explored it for sensing. The ammonia and VOCs measurements were performed for concentrations ranging from 5 to 500 ppm. The corresponding sensitivity and limit of detection of the developed sensor for ammonia gas detection was observed of the order of around 4.16 pm/ppm and 4.8 ppm, respectively. The response and recovery times of the sensor were found to be of the order of 50 s and 10 s, respectively, for the ammonia gas. This sensor provides a simple, cost-effective, highly sensitive, and repeatable approach to measure ammonia gas and other VOCs at room temperature and could fulfill the demands of industrial applications.