Terephthalate Substrate Research Articles

Enhancing hydrovoltaic power generation with carbon spheres coated on nickel foam/polyethylene terephthalate substrate

The present study aims to assess the viability of hydrovoltaic impact as a potential method for energy generation. This methodology utilizes the capillary action of water in devices composed of nickel (Ni) foam/polyethylene terephthalate (PET) substrates coated with hydrothermally synthesized carbon spheres at various temperatures (180, 200, and 220 °C). The prepared materials and devices were analyzed using a range of analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The SEM images revealed the spherical morphology of the carbon particles and their presence on Ni foam, whereas the XRD patterns indicated that the carbon spheres were amorphous. Spectroscopic analysis revealed the presence of hydroxyl functional groups in all the samples. The performance of the devices was assessed by electrochemical tests, including open-circuit potential (OCP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The device coated with carbon spheres synthesized at 180 °C demonstrated enhanced performance with an elevated OCP value of 0.077 V, increased surface charge area, lower resistance to water, and reduced charge transfer resistance. These findings indicate the successful production of hydrovoltaic energy by utilizing the capillary action of water in carbon-sphere-coated Ni foam/PET devices.

Process optimization and effect of sputtering pressure on electrochromic properties of flexible WO3 films prepared by DC magnetron sputtering

In this study, WO3 films were prepared on flexible indium tin oxide/polyethylene terephthalate substrates through DC magnetron sputtering at approximately 40 °C, and the process parameters were optimized. The effects of the sputtering pressure on the microstructure, morphology, and electrochromic properties of the films were investigated using Raman spectroscopy, scanning electron microscopy, x-ray diffraction, atomic force microscopy, and electrochemical techniques. The results showed that the thickness, surface roughness, and grain size of the WO3 films changed with increasing pressure, and the optimal values of these parameters for excellent electrochromic properties of the WO3 films were 731, 53.5, and 1.79 nm, respectively, at 2.0 Pa. The optical modulation amplitude reached 84.66% at 455 nm, and the coloring and bleaching response times were 7.64 s and 6.76 s, respectively. The electrochemical impedance spectroscopy results showed that the films prepared at 2.0 Pa had the smallest Rct (41.63 Ω).

Single-crystalline-level properties of ultrathin SrRuO3 flexible membranes with wide and clean surface

Transferring single-crystalline (SC) membranes to flexible substrates has been increasingly studied, enabling emerging functionality and enhanced performance of various devices. A commonly used support-assisted transfer process inevitably leaves dirty residue on material surfaces, limiting the further development of surface-related applications. Here, we scale down the thickness of flexible SC SrRuO3 (SRO) membranes to 15 nm with a clean surface area of 2.5 × 2.5 mm2. This is accomplished by making the polyethylene terephthalate (PET) substrate surface hydrophilic via oxygen plasma treatment, thereby reducing the surface tension. The ultrathin, clean, wide, and flexible SC SRO membranes guarantee a high transmittance of up to 60%, a low resistivity of 10−4−10−3 Ω cm at room temperature, and band ferromagnetism below 150 K with a high magnetic moment of ~0.5 μB/Ru at 10 K. The SC-level properties of our SRO membranes imply their potential use in state-of-the-art platforms for next-generation electronics and energy devices.

Versatile and Easily Designable Polyester-Laser Toner Interfaces for Site-Oriented Adsorption of Antibodies.

Laser toners appear as attractive materials for barriers and easily laminated interphases for Lab-on-a-Foil microfluidics, due to the excellent adhesion to paper and various membranes or foils. This work shows for the first time a comprehensive study on the adsorption of antibodies on toner-covered poly(ethylene terephthalate) (PET@toner) substrates, together with assessment of such platforms in rapid prototyping of disposable microdevices and microarrays for immunodiagnostics. In the framework of presented research, the surface properties and antibody binding capacity of PET substrates with varying levels of toner coverage (0–100%) were characterized in detail. It was proven that polystyrene-acrylate copolymer-based toner offers higher antibody adsorption efficiency compared with unmodified polystyrene and PET as well as faster adsorption kinetics. Comparative studies of the influence of pH on the effectiveness of antibodies immobilization as well as measurements of surface ζ-potential of PET, toner, and polystyrene confirmed the dominant role of hydrophobic interactions in adsorption mechanism. The applicability of PET@toner substrates as removable masks for protection of foil against permanent hydrophilization was also shown. It opens up the possibility of precise tuning of wettability and antibody binding capacity. Therefore, PET@toner foils are presented as useful platforms in the construction of immunoarrays or components of microfluidic systems.

Trained laser-patterned carbon as high-performance mechanical sensors

We describe the mechanical properties of turbostratically graphitized carbon films obtained by carbon laser-patterning (CLaP) and their application as bending or mechanical pressure sensors. Stable conductive carbonized films were imprinted on a flexible polyethylene terephthalate (PET) substrate by laser-induced carbonization. After initial gentle bending, i.e. training, these sponge-like porous films show a quantitative and reversible change in resistance upon bending or application of pressure in normal loading direction. Maximum response values of ΔR/R0 = 388% upon positive bending (tensile stress) and −22.9% upon negative bending (compression) are implicit for their high sensitivity towards mechanical deformation. Normal mechanical loading in a range between 0 and 500 kPa causes a response between ΔR/R0 = 0 and −15%. The reversible increase or decrease in resistance is attributed to compression or tension of the turbostratically graphitized domains, respectively. This mechanism is supported by a detailed microstructural and chemical high-resolution transmission electron microscopic analysis of the cross-section of the laser-patterned carbon.

Solution process formation of high performance, stable nanostructured transparent metal electrodes via displacement-diffusion-etch process

Transparent electrodes (TEs) with high chemical stability and excellent flexibility are critical for flexible optoelectronic devices, such as photodetectors, solar cells, and light-emitting diodes. Ultrathin metal electrode (thickness less than 20 nm) has been a promising TE candidate, but the fabrication can only be realized by vacuum-based technologies to date, and require tedious surface engineering of the substrates, which are neither ideal for polymeric based flexible applications nor suitable for roll-to-roll large-scale manufacture. This paper presents high-performance nanostructured transparent metal electrodes formation via displacement–diffusion-etch (DDE) process, which enables the solution-processed sub-20-nm-thick ultrathin gold electrodes (UTAuEs) on a wide variety of hard and soft substrates. UTAuEs fabricated on flexible polyethylene terephthalate (PET) substrates show a high chemical/environmental stability and superior bendability to commercial flexible indium–tin-oxide (ITO) electrodes. Moreover, flexible organic solar cells made with UTAuEs show similar power conversion efficiency but much enhanced flexibility, in comparison to that of ITO-based devices.

Morphological, structural, and optical properties of flexible Tin Oxide(II) thin film via thermal evaporation technique

Tin oxide compounds have been highly studied due to their important properties. Tin Oxide (II) SnO compound is considered an ideal p-type conductive material, with large p-type carrier mobility. It is getting a lot of attention in next-generation electronic applications. In this work, the SnO thin film was deposited on the polyethylene terephthalate (PET) substrate by the thermal evaporation method. The X-ray diffraction pattern revealed the amorphous structure of the SnO/PET thin film. The purity of the SnO/PET film was confirmed using the Raman spectrum. An atomic force microscope was carried out to investigate the topography (roughness and particle size) of the obtained SnO thin film. The optical band gap E_{{text{g}}}^{{{text{Opt}}}} for SnO/PET thin film in the absorption region was estimated using Tauc’s equation. The refractive index for the SnO/PET thin film was estimated at the normal dispersion range by a single oscillator model. The dielectric optical properties of the SnO/PET thin film were estimated. The calculated third-order nonlinear susceptibility χ(3) and nonlinear refractive index n(2) were in the order of ~ 10−10 and ~ 10−9esu, respectively, within the photon energy range (0.5 to 4 eV). The Sheik–Bahae model was used to determine the nonlinear absorption coefficient βc for SnO/PET thin film. Based on these detailed results, the high nonlinear optical parameters pave the way for the probability of using the SnO/PET in flexible optoelectronics devices.Graphical abstract

Effects and Mechanism of Surface Water Wettability and Operating Frequency on Response Linearity of Flexible IDE Capacitive Humidity Sensor.

Flexible capacitive humidity sensors are promising for low-cost, wearable, and radio frequency identification sensors, but their nonlinear response is an important issue for practical applications. Herein, the linearity of humidity response was controlled by surface water wettability and operating frequency of sensor, and the mechanism was explained in detail by surface water condensation. For a sensor with a Ag interdigitated electrode (IDE) on a poly(ethylene terephthalate) substrate, the capacitance showed a small linear increase with humidity up to 70% RH but a large nonlinear increase in the higher range. The response linearity was increased by a hydrophobic surface treatment of self-assembled monolayer coating while it was decreased by an ultraviolet/ozone irradiation for hydrophilicity. It was also increased by increasing the frequency in the range of 1–100 kHz, more prominently on a more hydrophilic surface. Based on experiment and simulation, the increase in sensor capacitance was greatly dependent on the geometric pattern (e.g., size, number, and contact angle) and electrical permittivity of surface water droplets. A larger and more nonlinear humidity response resulted from a larger increase in the number of droplets with a smaller contact angle on a sensor surface with higher water wettability and also from a higher permittivity of water at a lower frequency.

Effect of Mechanical Properties of Substrates on Flexibility of Ag Nanowire Electrodes under a Large Number of Bending Cycles

Ag nanowire electrodes have attracted considerable attention because of their potential applications in next-generation flexible electronics. However, there is a paucity of studies on the mechanical properties of Ag nanowire electrodes subjected to a large number of bending cycles. In this study, the effects of the substrate on the mechanical behavior of Ag nanowire electrodes were studied for a high bending frequency. The mechanical reliability of the Ag nanowire electrodes fabricated on a polyethylene terephthalate (PET) substrate was better than that for a polyimide (PI) substrate; the increase in the resistance of the PET-based Ag nanowire electrode was 1.07%, while that of the PI-based one was 1.23%. Nanoindentation tests showed that the elastic modulus of PI was larger than that of PET. This resulted in a lower bending strain on PET-based Ag nanowire electrodes compared to those on PI-based ones, because of the smaller distance from the neutral plane of the PET-based system. Our study showed that the mechanical properties of the substrate influenced the strain imposed on the thin layer on the substrates, which, in turn, determines the mechanical reliability of the thin-layer/substrate multilayer system.

Biomimetic Crack Sensors Using Electrohydrodynamic Technology.

This paper proposes a new mechanism for detecting microscopic damage of structures based on imitating the sensory organs of spiders. Therefore, it is essential to manufacture sensors that can react sensitively to the micro deformations of structures. Numerous cracks were intentionally generated to improve the sensitivity of the proposed sensor, and an increase in the gap of the crack was observed by scanning electron microscopy (SEM) observation. Electrohydrodynamic technology is used to detect deformations in a structure of depositing Ag nano paste on a polyethylene terephtha-late (PET) substrate. Ag nano lines are also observed by SEM images. The sensor is constructed as a grid structure, by forming layers patterned horizontally and vertically. An impact tester is used to verify the mechanism for structural health monitoring using the developed sensor. The resistance changes of the sensors are applied to estimate the structure's damaged location. The intersections of the lines with varying resistance can be used to accurately detect crack initiation. The proposed mechanism is a powerful methodology for estimating and detecting microscopic deformations and damage to structures.

Semitransparent Thin-Film Dual-Metal Anode for Red-Phosphorescent Organic Light-Emitting Diodes

Semitransparent dual-metal electrodes comprising several thin layers of metals, such as Ni, Ag, Cu, and Al, were developed for designing flexible red-phosphorescent organic light-emitting diodes (OLEDs). The said diodes were fabricated by first depositing a Ni layer on four glass and polyethylene terephthalate (PET) substrates each to facilitate adhesion with glass and a flexible PET substrate. Subsequently, a conductive layer of Ni, Ag, Cu, and Al was stacked atop the first Ni layer on the four glass and PET substrates each, respectively. The proof of principles has been employed to demonstrate the performance potential via optical, physical, and electrical analyses of dual-as well as single-metal layers prior to device realization. In addition, their electrical and optical characteristics were compared against those of In-Sn-oxide-based OLEDs to demonstrate their potential with regard to application flexibility.

Properties and Configurations of B-N Co-Doped ZnO Nanorods Fabricated on ITO/PET Substrate

Based on flexible materials, optoelectronic devices with optoelectronic technology as the core and flexible electronic devices as the platform are facing new challenges in their applications, including material requirements based on functional electronic devices such as lightness, thinness, and impact resistance. However, there is still a big gap between the current preparation technology of flexible materials and practical applications. At present, the main factors restricting the more commercial development of flexible materials include preparation conditions and performance. In this work, B-N co-doped ZnO nanorod arrays (NRAs) were successfully synthesized on the polyethylene terephthalate (PET) substrate coated with indium tin oxide (ITO) by the hydrothermal method. Based on the density functional theory, the effect of B-N co-doping on the electronic structure of ZnO was calculated; the incorporation of B and N led to an increase in the lattice constant of ZnO. The B-N co-doped ZnO has obvious rectification characteristics with the positive conduction voltage of 2 V in the I–V curve.

High Performance of IZO Coated on PET Substrate for Electroluminescence Device Using Oxygen Plasma Treatment

Thin films of indium zinc oxide (IZO) were deposited on polyethylene terephthalate (PET) substrate with varying plasma power (from 100 W to 300 W) using the radio-frequency (RF) magnetron sputtering technique and electroluminescence (EL) devices. The IZO films that were obtained from this process were treated with oxygen plasma powers using the plasma-enhanced chemical vapor deposition (PECVD) system. After this treatment, the microstructural, electrical, and optical properties of IZO films were observed and reported. The result showed that the IZO/PET films was fabricated at the lowest resistivity ( 2.83 × 10 − 3 Ω · cm ), while the optical characterization displayed the maximum transmittance of 95% in the visible region with a smooth morphology and good crystalline structured, affected by the 300 W of plasma power with the optimum carrier concentration ( 4.93 × 10 21 c m − 3 ) and hall mobility (42.12 cm2/V·sec), respectively. The luminance properties and the EL efficiency were also investigated and shown a 300 W highest point of plasma power with 84 cd/m2 and 0.924 lm/W. The film properties were found responsible for producing and improving the performance of IZO/PET substrate, suitable for displaying the devices.

Fabrication of high-performance flexible transparent conductive silver nanowire films using spray coating

Flexible silver nanowires (AgNWs) transparent conductive films (TCFs) were fabricated on poly(ethylene terephthalate) (PET) substrate by using spray coating process. Effects of concentration and amount of AgNWs suspension on the performances of optoelectronics and microstructures of AgNWs TCFs were investigated. The experimental results demonstrate that as the increase of both of concentration and amount of AgNWs suspension, the sheet resistance and nonuniformity factor of the sheet resistance (NUF) and transmittance of AgNWs TCFs decrease and the root mean square (RMS) roughness and figure of merit (FoM) and haze of the AgNWs TCFs increase, respectively, due to the increase of the deposition density of AgNWs on the substrate. The flexible AgNWs TCFs with excellent comprehensive performance, which is a NUF of 0.48, haze of 1.94%, FoM of 148.5, transmittance of 84.5%, and sheet resistance of [Formula: see text], can be obtained under the proper experimental conditions. The pressure treatment can improve the electrical conductivity of AgNWs TCFs due to the increase of contact area and the decrease of contact resistance. AgNWs TCF with pressure treatment also exhibits excellent reliability against mechanical bending over 1000 cycles. Our works demonstrate that flexible AgNWs TCFs with high performance can be obtained by using spray coating method, which is one of the common techniques for preparing coatings or films.

Effectiveness of electromagnetic interference shielding of sputtered nitrogen-doped carbon thin films

In this work, nitrogen-doped carbon (C:N) films are deposited on the aluminum/polyethylene terephthalate substrate by RF magnetron sputtering with different N2 flow rates. Film properties are characterized by transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The electrical properties are examined by Hall measurements, and the shielding efficiency is extracted from the network analyzer in the frequency range of 8.2–12.4 GHz. The Raman spectra suggest that N introduction in carbon films increases the intensity ratio of D-band (ID) to G-band (IG). A blue shift of the G-band is also observed. The Hall measurement reveals that the N doping acts as electron donor, leading to an increase in carrier concentrations and conductivity. Due to the improvement of electrical properties, more carriers interact with the incident EM field, resulting in an increased absorption loss through the C:N films. The electromagnetic interference shielding effectiveness, in terms of reflection loss and absorption loss, increases as well.

Flexible ECG circuit fabrication and application using vinyl cutting technique

The aim of this study is to prove the capability of vinyl cutting technique to cut the conductive traces of electronic circuit layout which used a copper tape (Copper tape 1181 from 3M) on flexible substrate to replace the method of using nano-scale particle material. A wireless electrocardiography (ECG) circuit was integrated and fabricated on flexible substrate, namely a polyethylene terephthalate (PET) substrate by using vinyl cutting method to produce the conductive line traces. After that, the fabricated circuit is used for acquiring ECG signals from a patient simulator and human subjects to measure the performance differences and compatibility as a wearable device. In the data processing stage, ECG data were denoised using sym20 from Wavelet Transform tool provided by MATLAB. Then, Signal-to-noise-ratio (SNR) was calculated and used as the signal quality indicator. At the end of the study, flexible circuit performance was compared to MIT-BIH Arrhythmia database and it shows that there is no significance difference between both. In conclusion, vinyl cutting method shows a promising fabrication output on PET substrate as the performance of both flexible ECG circuit is comparable with rigid ECG circuit by a previous study.

Dependence of Ionic Conductivity on the Thickness of β-AgI Thin Film Prepared on Polyethylene Terephthalate

β-AgI thin films with thicknesses of 0.09–8.9 µm were prepared on polyethylene terephthalate (PET) substrate. Dependence of ionic conductivity on the thickness of the β-AgI thin film was measured via impedance spectroscopy in the temperature range of 300–330 K. It has been confirmed that the ionic conductivity of the b-AgI thin film is several hundred times higher than the b-AgI bulk. The enhancement of ionic conductivity is considered to be due to the formation of a high ion-conducting region near the hetero-interface region of b-AgI and PET. Furthermore, it has been suggested that the activation energy and carrier density may change depending on the distance from the interface, and the thickness dependence of enhancement in ionic conductivity may be related to the film thickness dependence of crystal orientation and structural disorder of β-AgI thin films.

Flexible ZnO-mAb nanoplatforms for selective peripheral blood mononuclear cell immobilization

Cancer is the second cause of death worldwide. This devastating disease requires specific, fast, and affordable solutions to mitigate and reverse this trend. A step towards cancer-fighting lies in the isolation of natural killer (NK) cells, a set of innate immune cells, that can either be used as biomarkers of tumorigenesis or, after autologous transplantation, to fight aggressive metastatic cells. In order to specifically isolate NK cells (which express the surface NKp30 receptor) from peripheral blood mononuclear cells, a ZnO immunoaffinity-based platform was developed by electrodeposition of the metal oxide on a flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrate. The resulting crystalline and well-aligned ZnO nanorods (NRs) proved their efficiency in immobilizing monoclonal anti-human NKp30 antibodies (mAb), obviating the need for additional procedures for mAb immobilization. The presence of NK cells on the peripheral blood mononuclear cell (PBMCs) fraction was evaluated by the response to their natural ligand (B7-H6) using an acridine orange (AO)-based assay. The successful selection of NK cells from PBMCs by our nanoplatform was assessed by the photoluminescent properties of AO. This easy and straightforward ZnO-mAb nanoplatform paves the way for the design of biosensors for clinic diagnosis, and, due to its inherent biocompatibility, for the initial selection of NK cells for autotransplantation immunotherapies.

Understanding of the Mechanism for Laser Ablation-Assisted Patterning of Graphene/ITO Double Layers: Role of Effective Thermal Energy Transfer

Demand for the fabrication of high-performance, transparent electronic devices with improved electronic and mechanical properties is significantly increasing for various applications. In this context, it is essential to develop highly transparent and conductive electrodes for the realization of such devices. To this end, in this work, a chemical vapor deposition (CVD)-grown graphene was transferred to both glass and polyethylene terephthalate (PET) substrates that had been pre-coated with an indium tin oxide (ITO) layer and then subsequently patterned by using a laser-ablation method for a low-cost, simple, and high-throughput process. A comparison of the results of the laser ablation of such a graphene/ITO double layer with those of the ITO single-layered films reveals that a larger amount of effective thermal energy of the laser used is transferred in the lateral direction along the graphene upper layer in the graphene/ITO double-layered structure, attributable to the high thermal conductivity of graphene. The transferred thermal energy is expected to melt and evaporate the lower ITO layer at a relatively lower threshold energy of laser ablation. The transient analysis of the temperature profiles indicates that the graphene layers can act as both an effective thermal diffuser and converter for the planar heat transfer. Raman spectroscopy was used to investigate the graphite peak on the ITO layer where the graphene upper layer was selectively removed because of the incomplete heating and removal process for the ITO layer by the laterally transferred effective thermal energy of the laser beam. Our approach could have broad implications for designing highly transparent and conductive electrodes as well as a new way of nanoscale patterning for other optoelectronic-device applications using laser-ablation methods.

Finite element analysis on the sandwich structure of (MWCNTs/PET) composite under compression mechanism and different interfacial behaviors, buckling and tensile instability

This article is focused on buckling characteristics of fully profiled sandwich structure based on polyethylene terephthalate (PET) substrate and thicker Multi wall carbon nanotubes (MWCNT) which are bonded together using separate adhesives, Therefore this research article represents a new design and 3-D finite element analysis. Debonding mechanism for different MWCNTs layer number at a constant normal compressive load was studied and analyzed .The Rayleigh-Ritz and finite element analysis by Comsol Multi- physics software are used to predict the critical buckling load for various layer thicknesses of MWCNTs .The finite element calculation shows that a thinner [MWCNTs/PET] is more stable.