Polyethylene Terephtalate Substrates Research Articles

Design of a Flexible PET Based Yagi Dipole Antenna

In the proposed paper, a flexible Yagi Dipole Antenna based on PET Substrate is designed for the RF system-on-package (RF SOP) applications. RF antenna as a smart sensor is designed on a Flexible substrate Polyethylene Terephtalate (PET). It is the more popular and universally accepted thermoplastic polymer belonging to the family of the polyester. It is generally employed in textiles, thermoforming packaging along with glass fibers. In the proposed design Coplanar Strip line (CPS) is used as a feeder and the RF antenna is a Yagi dipole Antenna with a single driven element i.e. director, and a single reflecting element i.e. reflector. It is a linearly polarized antenna which means it radiates in a single direction. The antenna is designed at a resonating frequency of 5 GHz with a return loss of -23 dB. Simulations of the flexible PET based Yagi Dipole Antenna is carried out by using CST Studio Suite software for Return loss, Radiation plot with varied curvatures. The results for designed flexible Yagi Dipole Antenna imprinted with a PET substrate for portable wireless electronics are analyzed.

Read/Interrogation Enhancement of Chipless RFIDs Using Machine Learning Techniques

This letter describes the implementation of a machine learning (ML) classification strategy for read/interrogation enhancement in chipless radio frequency identification (RFID) applications. A novel ML-based approach for classification and of detection tag identifications (IDs) has been presented, which can perform effective transponder readings for a wide variety of ranges and contexts, while providing tag-ID detection accuracy of up to 99.3%. Four tags encoding the four 2 bit IDs were inkjet-printed onto flexible low-cost polyethylene terephtalate substrates and interrogated without crosstalk or clutter interference de-embedding at ranges up to 50 cm, with different orientations and with and without the presence of scattering objects in the vicinity of the tags and reader. A support vector machine algorithm was then trained using 816 measurements, and its accuracy was tested and characterized as a function of the included training data. Finally, the excellent performance of the approach, displaying reading accuracies ranging from 89.6% to 99.3%, is reported. This effort sets a precedent, opening the door to a rich and wide area of research for the implementation of ML methods for the enhancement of chipless RFID applications.

Metal‐Free Flexible Protonated g‐C3N4/Carbon Dots Photoanode for Photoelectrochemical Water Splitting

AbstractA metal‐free flexible protonated g‐C3N4/carbon dots (pCN/C dots) photoanode has been fabricated on polyethylene terephtalate (PET) /indium tin oxide (ITO) substrate by a facile room temperature electrophoretic approach. The pCN/C dots photoanode gives an increased anodic photocurrent of 38 μA/cm2 at 1 V vs. RHE under illumination with simulated one sun conditions, which is about 3 times higher than that of the pristine pCN. The improved photoresponse of the pCN/C dots film was found as a result from enhanced light absorption and decreased charge transfer resistance with the incorporation of C dots. The successful deposition of pCN/C dots on flexible conductive PET substrate holds promising application in multiple electronic and photoelectronic devices.

Micro-chip initiator realized by integrating Al/CuO multilayer nanothermite on polymeric membrane

We have developed a new nanothermite based polymeric electro-thermal initiator for non-contact ignition of a propellant. A reactive Al/CuO multilayer nanothermite resides on a 100 µm thick SU-8/PET (polyethyleneterephtalate) membrane to insulate the reactive layer from the silicon bulk substrate. When current is supplied to the initiator, the chemical reaction Al+CuO occurs and sparkles are spread to a distance of several millimeters. A micro-manufacturing process for fabricating the initiator is presented and the electrical behaviors of the ignition elements are also investigated. The characteristics of the initiator made on a 100 µm thick SU-8/PET membrane were compared to two bulk electro-thermal initiators: one on a silicon and one on a Pyrex substrate. The PET devices give 100% of Al/CuO ignition success for an electrical current >250 mA. Glass based reactive initiators give 100% of Al/CuO ignition success for an electrical current >500 mA. Reactive initiators directly on silicon cannot initiate even with a 4 A current. At low currents (<1 A), the initiation time is two orders of magnitude longer for Pyrex initiator compared to those obtained for PET initiator technology. We also observed that, the Al/CuO thermite film on PET membrane reacts within 1 ms (sparkles duration) whereas it reacts within 4 ms on Pyrex. The thermite reaction is 40 times greater in intensity using the PET substrate in comparison to Pyrex.

PRINTED ANTENNA ON FLEXIBLE LOW-COST PET SUBSTRATE FOR UHF APPLICATIONS

This paper introduces a ∞exible antenna, printed on a low-cost Polyethylene Terephtalate (PET) substrate for UHF applications. The RF characteristics of the PET substrate are examined using a microstrip resonator to characterize the substrate's relative permittivity and the loss tangent at UHF band. The PET substrate is used to print an antenna designed to work in the 868 ISM- Band. The printing process described is carried out using a semi- industrial roll-to-roll (R2R) machine with mass production capability. The fabricated dipole antenna was mounted on cylindrical objects made from several materials such as paper and glass, and its RF characteristics were measured and discussed.

Highly stable Ag–Ni based transparent electrodes on PET substrates for flexible organic solar cells

We report a novel transparent electrode structure made of Ag–Ni bilayer on polyethylene terephtalate (PET) substrates. However, without any adequate countermeasure, such an ultrathin layer would uninvitedly oxidize even at ambient conditions due to permeation of moisture and oxygen through the polymer substrates. A combination of heat and Ar plasma pretreatment was found to significantly increase the stability of the metals layers deposited onto polymer substrates. The 1nm Ni capping layer provides higher work function together with stability to the underlying Ag conducting layer over time and in harsh conditions of 85°C and 85% relative humidity. The obtained Ag–Ni bilayer ultrathin films show average transparency of 75% in the visible region and sheet resistance of 11Ω/sq. To demonstrate its operational potential, the electrode has been used as the transparent anode in an organic solar cell (OSC), which shows an overall photon conversion efficiency of >90% of the indium tin oxide (ITO) based cell which was measured to be 2.67%. With respect to ITO, the proposed transparent electrode has several advantages, including mechanical flexibility, room temperature processing and low cost.

Properties of TiO₂Thin Films Deposited on PET Substrate for High Energy Density Capacitor

thin films for high energy density capacitors were prepared by r.f. magnetron sputtering at room temperature. Flexible PET (Polyethylene terephtalate) substrate was used to maintain the structure of the commercial film capacitors. The effects of deposition pressure on the crystallization and electrical properties of films were investigated. The crystal structure of films deposited on PET substrate at room temperature was unrelated to deposition pressure and showed an amorphous structure unlike that of films on Si substrate. The grain size and surface roughness of films decreased with increasing deposition pressure due to the difference of mean free path. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of chemically stable films. The dielectric constant of films was significantly changed with deposition pressure. films deposited at low pressure showed high dissipation factor due to the surface microstructure. The dielectric constant and dissipation factor of films deposited at 70 mTorr were found to be 100~120 and 0.83 at 1 kHz, respectively. The temperature dependence of the capacitance of films showed the properties of class I ceramic capacitors. films deposited at 10~30 mTorr showed dielectric breakdown at applied voltage of 7 V. However, the films of 500~300 nm thickness deposited at 50 and 70 mTorr showed a leakage current of A at 100 V.

Edge Isolation of Transparent Conductive Polymer (TCP) Thin Films on Flexible Substrates using UV Laser Ablation

The purpose of this study was to directly use the writing techniques for the complex electrode edge isolation of transparent conductive polymer (TCP) thin films by a nanosecond pulsed UV laser processing system. The processing parameters including the laser pulse energy, the pulse repetition frequency, and the scan speed of galvanometers were examined to ablate the TCP films deposited on polyethylene terephtalate substrates of 188 microm thick. The thickness of TCP films was approximately 20 nm. The laser pulse repetition frequency and the scan speed of galvanometers were applied to calculate the overlapping rate of laser spots and to discuss the patterning region quality. Surface morphology, edge quality, and width and depth of edge isolated patterning structures after laser ablation process were measured by a three-dimensional confocal laser scanning microscope. In addition, the electrical conductivity of ablated TCP films was measured by a four-point probes instrument. After isolated line patterning was formed, the ablated TCP films with a better edge quality were obtained directly when the overlapping rate of laser spots, the scan speed, and the pulse repetition rate were 83.3%, 200 mm/s, and 40 kHz, respectively. The better surface morphology of electrode pattern structures was also obtained when the scan speed and the pulse repetition rate were 500 mm/s and 40 kHz, respectively.

Modification of electrospun nylon nanofibers using layer-by-layer films for application in flow injection electronic tongue: Detection of paraoxon pesticide in corn crop

The concern on exposure to hazardous pesticides caused by release of agrotoxic agents has motivated the development of new methods to analyze the quality of waters. This study reports on the modification of nylon nanofibers with layer-by-layer (LbL) films of conductive polypyrrole (PPy) and poly(o-ethoxyaniline) (POEA) that were assembled onto graphite interdigitated polyethylene terephtalate substrates, and used to detect pesticide in water. The electronic tongue apparatus, assembled to a flow analysis system, was able to distinguish water from different sources, with and without the presence of contaminants, at nanomolar concentrations. The practical utility of the system was demonstrated by discriminating the pesticide paraoxon in the water of corn washing in postharvest treatment, compared to water of other sources. The results presented here demonstrate the ability of the approach of modifying nylon nanofibers with LbL films of conductive polymers to be used as sensing units in the electronic tongue, to evaluate water quality regarding contamination by pesticides.

Characterization of indium tin oxide films by RF-assisted DC magnetron sputtering

A unique design of RF (radio frequency) assisted DC (direct current) sputter was employed to deposit ITO (indium tin oxide) films on PET (polyethylene terephtalate) substrate. Effects of different RF portions of total power and oxygen gas flow on the properties of the films were investigated. It was found that the films became denser as the applied RF portion of the total power increased. This is due to higher momentum energy transfer by impinging ions increasing adatom diffusion on the films. Thus, a larger grained and less porous microstructure was presented in the films deposited at higher RF portions of the total power. However, a rougher surface morphology and minor crystallization was also found in the films prepared at 100% RF power. By wisely adjusting to a 50% RF portion of the total power, the electrical resistivity can reach a minimum value of 5.4×10−4Ωcm associated with the carrier concentration of 7.0×1020cm−3 and mobility of 17.4cm2V−1s−1, respectively. In addition, the oxygen gas concentration in the sputtering chamber was found to play a key role in determining the quality of the films. As oxygen gas flowed at 2sccm, the electrical resistivity was decreased to 3.9×10−4Ωcm at a 50% RF portion of the total power. The electrical conduction mechanism, based on the grain boundary scattering, was correlated to the microstructure of the films in terms of grain size.

Influence of various thickness metallic interlayers on opto-electric and mechanical properties of AZO thin films on PET substrates

Various thickness metallic interlayers to improve the opto-electric and mechanical properties of aluminum-doped zinc oxide (AZO) thin films deposited on flexible polyethylene terephtalate (PET) substrates are studied. The effects of the interlayers on the resistance and transmittance of the AZO thin films are discussed. The result shows that the metallic interlayers effectively improve the electric resistance but reduce the optical transmittance of the AZO thin films. These phenomena become more obvious as the interlayer thickness increases. However, the AZO with an aluminum interlayer still behaves an acceptable transmittance. Moreover, mechanical tests indicate that the aluminum interlayer increases the hardness and modulus, and reduce the residual stress of the AZO thin films. In contrast, the silver and copper interlayers decrease the AZO's mechanical properties. Comparing to those without any interlayer, the results show that the best interlayer is the 6nm thick aluminum film.

Study of growth processes and mechanical properties of nanoscale multilayered C/C films

The growth processes of carbon films deposited using two techniques (sputtering and RF plasma assisted chemical vapor deposition, PACVD), and the effects of stacking these films in a multilayered structure on their mechanical and adhesion properties were studied. The films deposited by the two techniques differed in composition, structure and hardness. They are termed “hard C” and “soft C” according to their synthesis process, sputtering and PACVD respectively. By means of stress measurements and angle-resolved X-ray photoelectron spectroscopy, the growth mechanism of the films was characterized when they were deposited on a silicon substrate and when one kind of carbon film was deposited onto the other kind, in order to simulate a multi-layer film formation. This study evidenced the effect of converting the individual layer surfaces into interfaces when building a multilayer film. On one hand, this conversion appeared to increase the compressive stress of the multilayer films for the lowest periodicity (14nm and 7nm of half-period). On the other hand, a strong correlation between the stress resulting from multilayering and the film elasto-plastic properties was found. A hardening effect, put in evidence by applying a nano-indentation “plasticity index”, was obtained for the most layered films (i.e. with the lowest modulation period) and this effect is discussed in relation with the existing models for multi-layer strengthening. The film adhesion to polyethylene terephtalate (PET) substrates was investigated. A beneficial effect of multi-layering on film adhesion was significant only when the half-width period went down to 14nm and 7nm. The adhesion improvement cannot be related to a reduced internal stress, since the most stressed films were also the most adherent. Instead the compressive stress found in the films with the lowest periodicity is thought to induce a stronger bonding of the soft C layer (polymer-like) to the PET substrate and to the hard C layers, through chain entanglement across the interface.

Direct Metal Transfer Lithography for Fabricating Wire-Grid Polarizer on Flexible Plastic Substrate

This paper reports on the fabrication of polymer-based metallic wire-grid polarizers using a direct metal contact printing method. The proposed method can directly transfer a metal pattern from a silicon mold to a soft plastic substrate simply by roller pressing and infrared (IR) heating. With properly chosen loading contact pressure and heating temperature, metallic linear grating structures with a linewidth of 60 nm, a period of 170 nm, and an area size of 2.5 ×2.5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> are successfully formed on the surface of a polyethylene terephtalate (PET) substrate. The optical performance of the fabricated flexible polarizers is experimentally measured and numerically analyzed in the near-IR spectrum with wavelength from 800 to 1500 nm. Inspired by the numerical simulation results, the optical characteristics of the flexibe polarizers are further enhanced by reactive ion etching on the PET substrate. Good agreements between experiments and theoretical simulation are obtained. Future developments and potential applications of this metal contact transfer lithography method will be addressed.

Monolayered Wires of Gold Colloidal Nanoparticles for High-Sensitivity Strain Sensing

High-sensitivity resistive strain gauges based on electron tunneling in assemblies of gold colloidal nanoparticles are fabricated and characterized. The active area of these strain gauges consists in well-defined arrays of parallel, few micrometer wide wires of close-packed 18 nm gold nanoparticles. These nanoparticle wires are obtained by convective self-assembly (CSA) on flexible polyethylene terephtalate substrates, without any lithographic prepatterning. The fine control over the thickness and the width of the nanoparticle wires through the substrate temperature and the meniscus speed during the CSA process allows demonstrating the strong impact of the dimensionality (2D or 3D) of the nanoparticle assembly on the strain gauge sensitivity. Wires made of a single monolayer of nanoparticles turn out to give strain gauges about three times more sensitive than those made of multilayers. This work shows that the simplicity and versatility of convective self-assembly over other alternative methods make this ...

Thermomechanical and barrier properties of UV‐cured epoxy/O‐montmorillonite nanocomposites

AbstractMixtures of an epoxy resin and organophilic montmorillonites were subjected to ultraviolet (UV)‐induced photopolymerization. Two types of commercially available nanoclays, namely Cloisite 30B and Cloisite Na+, were modified through interaction with organic compatibilizers (dodecylsuccinic anhydride, octadecylamine, octadecyl alcohol, and octadecanoic acid). The modified nanoclays, dispersed in the liquid epoxy resin at 5 wt%, were photopolymerized to get nanocomposite films. The kinetics of the photopolymerization was evaluated by means of real‐time Fourier transform infrared spectroscopy. The modified nanoclays and their nanocomposites were characterized through X‐ray diffractometry; transmission electron microscopy showed the presence of intercalated and partially exfoliated morphologies in the nanocomposites. Thermogravimetric and dynamic‐mechanical analyses showed an increase of the thermal properties and an increase of the glass transition temperatures of the nanocomposites compared with that of the neat UV‐cured resin. Finally, the oxygen barrier properties of nanocomposite films, coated on a polyethyleneterephtalate substrate, were evaluated; the decrease of permeability was correlated with the degree of exfoliation of the nanocomposites. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

On the essential work of fracture in polymer–metal multilayers

Polyethylene terephtalate (PET) metallized with aluminium by physical vapour deposition was investigated through classical physical chemistry techniques and mechanical characterization. The amount of aluminium altered the amount of crystallinity of the PET substrate, but appeared unrelated to the mechanical properties obtained with regular tensile test. In contrast, the essential work of fracture (EWF), as obtained with Cotterell tests, permitted to better discriminate the perforation resistance. It is shown that increasing the amount of crystallinity within the PET linearly reduced the EWF.

Chromaticity (b*) and Transmittance of ITO Thin Films Deposited on PET Substrate by Using Roll-to-Roll Sputter System

Indium Tin Oxide (ITO) thin films on Polyethylene Terephtalate (PET) substrate were prepared by Roll-to-Roll sputter system with targets of 5 wt% and 10 wt% <TEX>$SnO_2$</TEX> at room temperature. The influence of the chromaticity (b*) and transmittance properties of the ITO Films were investigated. The ITO thin films were deposited as a function of the DC power, rolling speed, and Ar/<TEX>$O_2$</TEX> gas flow ratio, and then characterized by spectrophotometer. Their crystallinity and surface resistance were also analyzed by X-ray diffractometer and 4-point probe. As a result, the chromaticity (b*) and transmittance of the ITO films were broadly dependent on the thickness, which was controlled by the rolling speed. When the ITO films were prepared with the DC power of 300 W and the Ar/<TEX>$O_2$</TEX> gas flow ratio of 30/1 sccm using 10 wt% <TEX>$SnO_2$</TEX> target as a function of the rolling speeds 0.01 through 0.10 m/min, its chromaticity (b*) and transmittance were about -4.01 to 11.28 and 75.76 to 86.60%, respectively. In addition, when the ITO films were deposited with the DC power of 400W and the Ar/<TEX>$O_2$</TEX> gas flow ratio of 30/2 sccm used in 5 wt% <TEX>$SnO_2$</TEX> target, its chromaticity (b*) and transmittance were about -2.98 to 14.22 and 74.29 to 88.52%, respectively.

The power source effect on SiO x coating deposition by plasma enhanced chemical vapor deposition

SiOx coatings were prepared by capacitively coupled plasma enhanced chemical vapor deposition on polyethyleneterephtalate substrates in 23 kHz middle-frequency and radio frequency power supplies, respectively, where hexamethyldisiloxane was used as gas source. The influences of discharge conditions on gas phase intermediate species and active radicals for SiOx formation was investigated by mass spectrometry as real-time in-situ diagnosis. The deposited SiOx coating chemical structures were also analyzed by Fourier transform infrared spectroscopy. Meanwhile, the film barrier property, oxygen transmission rate, was measured at 23 °C and 50% humidity circumstance. The better barrier property was obtained in the MF power source depositing SiOx coated PET.

Adhesion of Campylobacter jejuni and Mycobacterium avium onto polyethylene terephtalate (PET) used for bottled waters

Adhesion of the bacteria Campylobacter jejuni and Mycobacterium avium onto polyethylene terephtalate (PET), a polymer widely used within the bottled water industry was measured in two different groundwater solutions. From this, it was found that whilst the percentage cell adhesion for a given strain did not change between groundwater types, substantial variation was obtained between the two bacterial species tested: M. avium (10–30% adhered cells) and C. jejuni (1–2%) and no major variations were measured as a function of groundwater composition for a given strain. To explain this, the interfacial electro-hydrodynamic properties of the bacteria were investigated by microelectrophoresis, with the resultant data analysed on the basis of electrokinetic theory for soft biocolloidal particles. The results obtained showed that M. avium carries a significant volume charge density and that its peripheral layer exhibits limited hydrodynamic flow permeation compared to that of C. jejuni. It was also demonstrated that steric hindrance to flow penetration and the degree of hydrophobicity within/of the outer bacterial interface are larger for M. avium cells. In line with this, the larger amount of M. avium cells deposited onto PET substrates as compared to that of C. jejuni can be explained by hydrophobic attraction and chemical binding between hydrophobic PET and outer soft surface layer of the bacteria. Hydrophobicity of PET was addressed by combining contact angle analyses and force spectroscopy using CH 3-terminated AFM tip.

Microstructure and Resistivity of Low Temperature Deposition ITO Films on PET Substrate by Magnetron Sputtering

Sn doped indium oxide (ITO) films were fabricated on polyethylene terephtalate (PET) substrate by magnetron sputtering at low deposition temperature using a 10 wt % SnO2-doped In2O3 target applied in the infrared regions as low emissivity materials. The microstructure and surface morphology of ITO films was studied using X-ray diffraction (XRD) and atomic force microscopy (AFM); the resistivity was investigated by four-point probe technology. It was found that the film with amorphous microstructure has highest resistivity to 1.956×10-3 2.cm at low deposition temperature and the surface roughness and resistivity increase with the increasing Ar sputtering pressure from 0.5Pa to 1.4Pa. The most interesting is that the resistivity increases with the increasing surface roughness, it indicates that there are internal correlation between roughness and resistivity.