Flexible Polyethylene Terephthalate Film Research Articles

Strong Interface Interaction of ZnO Nanosheets and MnSx Nanoparticles Triggered by Light over Wide Ranges of Wavelength to Enhance Their Removal of VOCs

The characteristics of the surface and interface of nanocomposites are important for exerting multi-functional properties and widening interdisciplinary applications. These properties are mainly depending on the electronic structures of materials. Some key factors, such as the surface, interface, grain boundaries, and defects take vital roles in the contribution of desired properties. Due to the excellent sensitivity of the QCM (quartz crystal microbalance) device, the surface and interface features of the nanocomposite were studied with the aid of the gas-response of the sensors (Sensor’s Gas-Sensitivity) in this work. To make full use of the visible light and part of NIR, a ZnO/MnSx nanocomposite was constructed using hydrothermal synthesis for narrowing the bandgap width of wide bandgap materials. The results indicated that the absorbance of the resulting nanocomposite was extended to part of the NIR range due to the introduction of impurity level or defect level, although ZnO and MnS belonged to wide bandgap semiconductor materials. To explore the physical mechanism of light activities, the photoconductive responses to weak visible light (650 nm, etc.) and NIR (near-infrared) (808 nm, 980 nm, and 1064 nm, etc.) were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with the casting method. The results showed that the on/off ratio of ZnO/MnSx nanocomposite to weak visible light and part of NIR light were changed by about one to five orders of magnitude, with changes varying with the amount of MnSx nanoparticle loading due to defect-assisted photoconductive behavior. It illustrated that the ZnO/MnSx nanocomposite easily produced photo-induced free charges, effectively avoiding the recombination of electrons/holes because of the formation of strong built-in electrical fields. To examine the surface and interface properties of nanocomposites, chemical prototype sensor arrays were constructed based on ZnO, ZnO/MnSx nanocomposite, and QCM arrays. The adsorption response behaviors of the sensor arrays to some typical volatile compounds were examined under a similar micro-environment. The results exhibited that in comparison to ZnO nanosheets, the ZnO nanosheets/MnSx nanocomposite increased adsorption properties to some typical organic volatile compounds significantly. It would have good potential applications in photo-catalysts, self-cleaning films, multi-functional coatings, and organic pollutants treatment (VOCs) of environmental fields for sustainable development. It provided some reference value to explore the physical mechanism of materials physics and photophysics for photo-active functional nanocomposites.

Impact of piezo-phototronic effect on ZnMgO/Se heterojunction photovoltaic devices

This paper investigates the impact of piezo-phototronic effects on the power conversion efficiency of ZnMgO/Se heterojunction photovoltaic devices. Sputter-deposited ZnMgO thin film and photo-absorbing Se were employed as the n-type window layer and p-type layer, respectively, to form a photovoltaic device on a flexible polyethylene terephthalate film. The applied strain was varied, and the changes due to the applied strain were recorded. The open-circuit voltage (Voc) increased from 0.59 V to 0.75 V when the applied strain was increased from − 0.41–0.40% by varying the bending angle. It has been reported that piezoelectric polarization of ZnMgO can decrease conduction band offset (CBO) between the ZnMgO and Se layers.

Complete recycling and valorization of waste textiles for value-added transparent films via an ionic liquid

Waste polyester-cotton blended textiles have huge production and most of them are incinerated and landfilled, leading to seriously environmental pollution and significant waste of natural resources. Hence, recycling these textile wastes to other value-added products in a sustainable and economical way is meaningful and urgent. In order to completely utilize and valorize polyester-cotton blended textiles, transparent regenerated cellulose films and high-purity recovered polyethylene terephthalate (PET) film were successfully prepared via ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). It is indicated that cotton fibers in waste polyester-cotton blended fabrics can be fully dissolved in AmimCl, resulting in efficient separation of polyester and cotton. The transparent cellulose films can be achieved after coagulating and drying processes. Moreover, the changes in morphology and crystalline structure of cellulose films regenerated in different coagulation bath were also investigated in detail, in which cellulose films with dense structure regenerated from water coagulation bath exhibited good mechanical properties and tensile strength was as high as 35 MPa, much higher than that of polyethylene (PE, 9 MPa) self-sealing bag membrane commonly used in laboratory, showing great potential application in packaging and wrapping fields. Meanwhile, the high purity PET residue was also reused as raw material to fabricate transparent and flexible PET film by melt pressing, whose tensile strength can reach 36 MPa. Consequently, a facile and eco-friendly process of recycling and reusing polyester-cotton blended textiles was developed and the high-valued utilization of waste polyester-cotton blended textiles can also be realized.

A graphenic and potentiometric sensor for monitoring the growth of bacterial biofilms

Biofilm development on surfaces represents one of the most challenging issues in the medical field. The irreversibility of the biofilm developmental process, and the peculiar characteristics of biofilms (including the low permeability to antibacterial compounds), make biofilm associated infections difficult to treat and prone to relapse. Thanks to the short response time, low-cost, easy fabrication and potential for miniaturization, electrochemical sensors are expected to play an important role in monitoring biofilm formation. Here, we describe the use of a potentiometric sensor based on functionalized reduced graphene oxide for monitoring the formation and growth of biofilms from three bacterial species (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) in liquid and semisolid culture media. The Open Circuit Potential (OCP) between an Ag/AgCl pseudo reference electrode and a working electrode, both screen-printed on a flexible polyethylene terephthalate film, was measured during the growth of bacteria. The OCP decreased over time as bacteria grew on the sensor surface exhibiting a negative correlation.

Controlled Island Formation of Large-Area Graphene Sheets by Atmospheric Chemical Vapor Deposition: Role of Natural Camphor.

Camphor-based mono-/bilayer graphene (MLG) sheets have been synthesized by very facile atmospheric chemical vapor deposition processes on Si/SiO2, soda lime glass, and flexible polyethylene terephthalate films. The effect of camphor concentration with respect to distance between camphor and the Cu foil (D) has been varied to investigate the controlled formation of a homogeneous graphene sheet over a large area on Cu foil. Raman studies show a remarkable effect of camphor at a typical distance (D) to form a monolayer to multilayer graphene (MULG) sheet. The signature of MLG to MULG sheets appears due to increase in the number of nucleation sites, even over the subsequent domains that contribute stacks of graphene over each other as observed by high-resolution transmission electron microscopy images. Moreover, the increase in camphor concentration at a particular distance generates more defect states in graphene as denoted by D band at 1360 cm–1. Uniform distribution of large-area MLG demonstrates an intense 2D/G ratio of ∼2.3. Electrical and optical measurements show a sheet resistance of ∼1 kΩ/sq with a maximum transmittance of ∼88% at 550 nm for low camphor concentration. An improvement in the rectification and photodiode behavior is observed from the diodes fabricated on n-Si/MULG as compared to n-Si/MLG in dark and light conditions.

Low-profile flexible frequency-reconfigurable millimetre-wave antenna for 5G applications

This paper presents the design and characterisation of a flexible, inkjet-printed, low-profile, and frequency-reconfigurable antenna, intended for the fifth generation (5G) wireless networks operating at millimetre-wave (mm-wave) frequency bands. The antenna geometry is comprised of a slotted T-shaped radiating patch embedded in a rectangular aperture cut inside the ground plane. The slots are designed with two pairs of switches to reconfigure the radiating area for the desired selection of operating frequency at the Ka-band (26.5–40 GHz). Moreover, a two-element inkjet-printed multiple-input multiple-output (MIMO) antenna assembly is proposed based on a flexible polyethylene terephthalate film. The conformal MIMO antenna is suitable for integration in high-performance flexible 5G front-ends, as well as in next-generation wearable electronic devices and applications.

Novel method for the detection of the facial nerve using electrical impedance spectroscopy during otologic surgery

Iatrogenic facial nerve injuries, which may occur during otologic surgery, can cause facial paralysis that eventually leads to devastating complications such as cosmetic problems, limitation to eye lubrication, and problems with eating, drinking, and speaking. We aimed to prevent iatrogenic nerve injury using an electrical impedance spectroscopy (EIS) technique and developed a facial nerve detector (FND) with coplanar bipolar electrodes on a flexible polyethylene terephthalate film using micro electro-mechanical systems technology. The discrimination capability of the FND was preliminarily evaluated by analyzing electrical impedances of solutions of various concentrations of phosphate-buffered saline and by extracting sample resistance using curve fitting with an electrical equivalent circuit. The impedances of bone, facial nerve covered by thin bone, and facial nerve of a cadaver were investigated using the optimal frequency range obtained based on the proposed discrimination index. To generalize the sensor output without regard to the shapes and dimensions of the EIS sensors, electrical conductivities of the samples were estimated by matching the extracted sample resistances with resistances obtained in the finite element method (FEM) simulation. Finally, in order to determine the location of the facial nerve before the facial nerve is exposed, resistance and conductivity changes were investigated using an FEM simulation based on the thickness of the bone covering the facial nerve. Thus, physicians can obtain information regarding the thickness of the bone covering the facial nerve while grinding the bone in otologic surgery. This will enable physicians to easily avoid iatrogenic facial nerve injury during otologic surgery.

Flexible Organic Tribotronic Transistor for Pressure and Magnetic Sensing.

Flexible electronics has attracted enormous interest in wearable electronics and human-machine interfacing. Here, a flexible organic tribotronic transistor (FOTT) without a top gate electrode has been demonstrated. The FOTT is fabricated on a flexible polyethylene terephthalate film using the p-type pentacene and poly(methyl methacrylate)/Cytop composites as the conductive channel and dielectric layer, respectively. The charge carriers can be modulated by the contact electrification between the dielectric layer and a mobile triboelectric layer. Based on the fabricated FOTT, pressure and magnetic sensors have been developed, respectively, that exhibit great sensitivity, fast response time, and excellent stability. The FOTT in this simple structure shows bright potentials of tribotronics in human-machine interaction, electronic skins, wearable electronics, intelligent sensing, and so on.

A flexible, gigahertz, and free-standing thin film piezoelectric MEMS resonator with high figure of merit

In this paper, a 2.6 GHz air-gap type thin film piezoelectric MEMS resonator was fabricated on a flexible polyethylene terephthalate film. A fabrication process combining transfer printing and hot-embossing was adopted to form a free-standing structure. The flexible radio frequency MEMS resonator possesses a quality factor of 946 and an effective coupling coefficient of 5.10%, and retains its high performance at a substrate bending radius of 1 cm. The achieved performance is comparable to that of conventional resonators on rigid silicon wafers. Our demonstration provides a viable approach to realizing universal MEMS devices on flexible polymer substrates, which is of great significance for building future fully integrated and multi-functional wireless flexible electronic systems.

Nanocomposites of Carbon Nanotube/Polyaniline with Pending Calix[8]Arene and their External Stimuli Response Properties

To functionalize the smart nanocomposites, the nanocomposites of CNTs/polyaniline with pending calix [8] arene were prepared. A series of characterizations were performed by SEM (scanning electron microscopy), the Fourier-Transform Infrared (FTIR) spectra, The UV-Vis (Ultra-violet visible spectroscopy), et al. The photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The results showed that the nanocomposites of CNTs/polyaniline with pending calix [8] arene exhibited good photoresponse to visible light and weak 808 nm laser, but its recoverability was very slow, it needed several hours, and the film-forming property of nanocomposite was not very good. This may be attributed to the results of increased hydrophobicity of nanocomposite because of introducing the calix [8] arene ring. In order to increase the film-forming technology of nanocomposites, the grapheme oxide were obtained with unzipping method of carbon nanotube (CNTs) for enhancing the hydrophilcity of carbon nanomaterials. The nanocomposites of grapheme oxide/polyaniline with pending calix [8] arene were obtained with similar methods, which showed improved film-forming property. The photoresponses to weak visible light and 808 nm laser also showed the similar results. It may develop the nanocomposite with external stimuli response, and have good potential applications in sensors, organic photocatalyst, et al.

Organic Functionalization and Properties of ZnO Nanosheets with Polymer Containing N-Vinyl Carbazole

To make full use of the visible light more effectively, many studies are focuses on ZnO baesd nanocomposites. To modify the surface of ZnO with functional polymer is a very simple and effective approach. PVK (N-vinyl carbazole polymer) is one of typical organic functional materials, which is generally used as charge transfer materials for the applications of several organic electronic devices. Surface modification of ZnO nanosheets with polymer containing –COOH and N-vinyl carbazole group was performed with self-assembly process for improving the adsorption to visible light and properties of charge transfer in nanoscale. A series of characterizations were carried out by SEM (scanning electron microscopy), Fourier-Transform Infrared (FTIR) spectra, UV-Vis (Ultra-violet visible spectroscopy), et al. The adsorption of the nanocomposite was extended to the region of visible light. The photoconductivity response to weak visible light was studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The photocurrent of ZnO nanosheets modified with the polymer containing N-vinyl carbazole to weak visible light was changed greatly. The organic-inorganic nanocomposite showed good activities to visible light, with which it can be easily produced photo-induced charges, avoiding the recombination of charges produced by visible light. Photocatalytic efficiency was examined by selecting typical organic pollutants and some good results were obtained, showing much prospect in the fields of photocatalysts, nanoreactors, self-cleaning films, coatings, and organic pollutants treatment of environmental.

Photo-Induced Charge Generation of TiO<sub>2</sub> Nanotube Modified with Polymer Containing C<sub>60</sub> under Irradiation of Visible Light and its Applications

Due to its excellent physical properties and inert chemical reaction activity of C60, it is possible to synthesize solution-processing polymer containing C60 utilizing the inclusive characteristics of polymer chain segment, and then to prepare organic/inorganic nanocomposites with enhanced some key properties. In order to harvest the visible light of TiO2 effectively the surface modification of TiO2 nanotube with polymer containing C60 was carried out in this study. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), Fourier-Transform Infrared (FTIR) spectra, UV-Vis (Ultra-violet visible spectroscopy), XRD patterns analysis. The results showed that the UV-Vis of resulting nanocomposite was almost covered the whole region of visible light. The photoconductivity response to visible light with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate with casting method. The results indicated that the photoresponses of two kinds of polymer containing C60 to weak visible light emerged photo-switching behavior, its recoverability was also rapidly, and the photoresponse of TiO2 nanotube modified with two kinds of polymer containing C60 to weak visible light also changed greatly. This illustrated that the organic-inorganic nanocomposites showed good activities to weak visible light. Photocatalytic efficiency was examined by selecting typical organic pollutants, some good results were obtained. It may develop organic-inorganic nanocomposites with external stimuli response, photocatalyst, et al.

Surface Modification of Graphene Oxide with Pyrene Derivatives and their Photo-Switching Behaviors

The characteristics of surface and interface of nanocomposites are favor for exerting some functional properties and widening new applications. Some low-dimensional materials generally have abundant chemical groups and reaction activities. These surface chemical groups of nanomaterials provide a large platform to develop new nanocomposites and applications by surface chemical reaction and surface reconstruction of another kind of materials. Among so many hot-fields materials, graphene and its nanocomposite are developed rapidly. The graphene oxide not only has good charge transferring property, but also has abundant chemical groups on its surface, such as, -COOH, -OH and epoxide group. Therefore, graphene oxide is a good candidate substrate for further constructing other functional materials in nanoscale. The graphene oxide and pyrene derivatives were selected as representative materials for studies. Assembly of pyrene containing –NH2 groups on the surface of graphene oxide was carried out. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), the FTIR (Fourier-Transform Infrared ) spectra, The UV-Vis (Ultra-violet visible spectroscopy), photoluminescence spectra, et al. The results indicated that the UV-Vis of nanocomposite was almost covered the whole region of visible light, and the results of PL showed strong fluorescence quenching. There was strong interaction between the graphene oxide and pyrene. The photoconductivity response to weak visible light and 808 nm laser were studied based on interdigital electrodes of Au on flexible PET(polyethylene terephthalate) film substrate with casting method. The results showed that graphene oxide modified with pyrene derivatives exhibited that the photocurrent increased obviously to visible light, and photoresponse to weak 808 nm laser emerged photo-switching behavior. It would be developed the light detector to NIR, biomimetic fields or external stimuli driven nanocarriers for biomedical fields, et al.

Flexible polymer opal films prepared by slide coating from alcoholic media

In this study, we investigated the fabrication of a colloidal photonic crystal film on flexible substrate, which can be used as a scaffold material for various photonic applications. A thin polyethylene terephthalate (PET) film was treated by oxygen plasma and then used as a flexible substrate. The surface characterizations revealed that the surface roughness increased, and that the treated PET film was rendered hydrophilic. The contact angles of the films with water/isopropyl alcohol (IPA) mixtures at five different weight ratios (25%, 40%, 50%, 60%, and 75% of IPA) prepared on both treated and non-treated PET films were measured. The results indicated that water/IPA wets on oxygen plasma-treated PET film. The colloidal dispersions were prepared in five different water/IPA mixtures, and slide coating was carried out on both PET films aided by hot air to promote opal formation. Serious dewetting of opal film was observed on the non-treated PET film, except that with a 75% IPA. However, the treated PET film enabled the formation of high-quality opal film, regardless of IPA content in colloidal dispersion. The optical properties and surface morphologies of opal films on flexible PET film were confirmed by reflectance spectra and scanning electron microscopy images of the respective films.

A wearable textile antenna for wireless power transfer by magnetic resonance

The paper presents a wearable textile antenna embroidered on a fabric for wireless power transfer systems. A planar spiral coil was generated with the conductive thread on a cotton substrate, and was connected to a rectifier circuit fabricated on flexible polyethylene terephthalate film to constitute a bendable receiver by the magnetic resonance. At a resonance frequency of 6.78 MHz, the proposed system could achieve −5.51 dB transfer efficiency and 12.75 mW power transmission at a distance of 15 cm. It was also demonstrated that the resonance frequency and transmitted power of the proposed system could be maintained as the same even when the system was bent conformingly to the surface curvature of the human body model for a bending radius up to 50 mm or larger.

Pressure sensors gaining durability

Researchers in Singapore have done what most materials scientists can only dream about: They ran their project over with a car. But this act wasn’t born of frustration. Rather, it demonstrated the durability of pressure sensors made from eutectic gallium indium, or eGaIn, a metal that’s liquid at room temperature (ACS Sens. 2016, DOI: 10.1021/acssensors.6b00115). To create their device, researchers at the National University of Singapore dispense electrically conductive eGaIn into a cavity they have patterned within a silicone elastomer. They then seal the device with a flexible polyethylene terephthalate film that also supports two electrodes made from screen-printed silver. Squishing a device redistributes the liquid metal and alters the resistance between the electrodes, converting pressure changes to electrical signals. The sensor is durable enough to stomp on, but soft and flexible enough to wear inside a shoe, the researchers report. They could even discern whether it was worn inside

Charge Behavior of Low-Dimensional V<sub>2</sub>O<sub>5</sub>/Graphene Nanoribbons Oxides Nanocomposites under Irradiation of Visible Light and its Application

Due to its outstanding photo-catalysis properties, low-dimensional V2O5 has many important applications in lithium ion batteries, supercapacitors, electrochromic devices, photocatalysts, sensors, et al. As good photocatalysts for organic pollutants, some key issues of photocatalysts are charge generation, separation, transfer of nanocomposites under irradiation of visible light. To improve their important properties and pave the effective conductive channels for charge transfer and separation, low-dimensional V2O5/graphene nanoribbons nanocomposites were prepared. The emphasis is put on adsorption response to VOC of nanocomposite based on the QCM (quartz crystal microbalance) device. In order to investigate the mechanism of charge-generated by visible light, the photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate. Some good results were obtained. This illustrates that this nanocomposite can easily produce the charge-generate with visible light and 808 nm laser with low-power, avoiding the recombination of charge-generate by light. It would be good applications in remove the organic pollutants with photocatalysis effects.

Two-Dimensional Composite Biomimetic Films with Wide Optical Spectrum Response and their Properties

Since graphene was discovered, the biomimetic materials with laminated structure (such as, shellfish) had become one of the research-hot fields. Chitosan comes from shellfish, and was considered as a very promising abundant natural biopolymer. It holds not only outstanding mechanical properties, film-forming technology and low cost, but also has good applications in environmental fields due to its excellent adsorption properties to a broad range of organic pollutants and some heavy metal ions. Preparation of biomimetic materials with laminated structure utilizing chitosan have many advantages, however, to improve functional properties of chitosan based biomimetic materials is still a great challenge. Graphene has various applications, including storage energy devices, hydrogen production with photo-catalysts, and environmental fields because of its high charge mobility and good mechanical properties. However, graphene and its oxide have difficult re-dispersion properties in fabrication of nanocomposite. In this paper, the nanosheets stacking of metal oxide and grapheme oxide with aid of chitosan was carried out. Several characterizations were examined by SEM (scanning electron microscopy), XRD (X-ray diffraction), ultraviolet-visible spectroscopy (UV-Vis), and Fourier-Transform Infrared (FTIR) spectra. Photocatalytic tests were examined by selecting typical organic pollutants. The photoconductivity response of nanocomposite film to visible light and 808 nm laser with low-power were investigated based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate. The results indicated that the organic-inorganic film not only had wide visible light and NIR (near-infrared) responses, but also had good removal ability to organic pollutants. The nanocomposite film also exhibited clearly photo-response to visible light and 808 nm laser. It would be potential good applications in self-cleaning film, nanocoating, et al.

Surface Modification of Low-Dimensional Heterostructured Functional Materials with Dendrimers and their Properties of Organic-Inorganic Nanocomposites

Low-dimensional heterostructured functional materials have been widely applied in new energy materials, catalysts, et al. However, to enhance photo-response in visible light and the biocompatibility improvement are still the great challenges faced. And the dendrimers act good roles in transferring the drug and gene, and has good biocompatibility. Self-assembly on the surface of low-dimensional heterostructured functional materials with dendrimers holding-COOH groups was carried out in this paper. The characterizations of the materials were examined by SEM (scanning electron microscopy), XRD (X-ray diffraction), the Fourier-Transform Infrared (FTIR) spectra, ultraviolet-visible spectroscopy (UV-Vis) and so on. The photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET (polyethylene terephthalate) film substrate. The results indicated that ZnO/CuS modified with dendrimers showed good photo-response to visible light and 808 nm laser, the photo-response properties enhanced greatly by adding some small amount of grapheme oxide. Photocatalytic efficiency was examined by selecting typical organic pollutants, some good results were obtained. The external stimuli driven nanorobots for removal the organic pollutants or toxins in the living body have been developed.

NIR (Near-Infrared) Driven Carbon Nanotube Modified with Dendrimers

Dendrimers and carbon nanotube took an important role in transport and delivery of drugs, gene, et al, however, to improve its functional properties is still a great challenge. Carbon nanotube not only has good biocompatibility but also hold optical adsorption in NIR. In biomimetic and biomedical fields, nanorobots or nanocarriers with external stimuli response for removal the organic pollutants and toxins or drugs in the living body are attractive for research and applications. In this paper, the self-assembly with CNTs containing –COOH and dendrimers having –NH2 groups was carried out. A series of characterizations were performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (X-ray diffraction), and Fourier-Transform Infrared (FTIR) spectra. The adsorption properties and releasing characteristics of CNTs modified with dendrimers were performed with simulating drugs. Some meaningful results were obtained. The photoconductivity response to visible light and 808 nm laser with low-power were studied based on interdigital electrodes of Au on flexible PET(polyethylene terephthalate) film substrate. The results indicated that CNTs modified with dendrimers showed good photo-response to visible light and 808 nm laser. It would be developing smart nanorobots with external stimuli response for removal the organic pollutants and toxins or drugs in the living body.