Indium Tin Oxide Glass Substrate Research Articles

A Novel EWOD Platform for Freely Transporting Droplets in Double and Single-Plate Structures.

This study developed a novel dielectric wetting microfluidic operation platform combining parallel-plate and coplanar-plate regions with a curved surface structure as the connection structure. With the new electrowetting on dielectric (EWOD) platform, "droplet pull-out" has been successfully achieved and viewed as an essential new operation for microfluidics with the dielectric wetting technique. The EWOD system is divided into a PDMS substrate top plate and an indium tin oxide (ITO) glass substrate as a bottom layer on this chip. In the parallel-plate region, the droplets can be generated and transported through the square parallel electrodes; in the single-plate area, the droplets can be pulled out from the parallel structure, transported and mixed through the common grounded coplanar electrodes. In dielectric wetting performance testing, coplanar electrodes can apply a maximum driving force of 31.22 µN to DI water and 13.38 µN to propylene carbonate (PC). This driving force is sufficient to detach the sample from the top cover and pull the sub-droplet from the parallel plate structure for DI water, PC and polyethylene glycol diacrylate (PEGDA) buffer. The novel EWOD system also possesses the advantage of precise volume control for liquid samples; the volume error of the generated droplet can be controlled within 0.1% to 2%.

A novel integrated lateral flow immunoassay platform for the detection of cardiac troponin I using hierarchical dendritic copper-nickel nanostructures

Cardiac troponin I (cTnI) is a critical biomarker for the diagnosis of acute myocardial infarction (AMI). Herein, we report a novel integrated lateral flow immunoassay (LFIA) platform for highly sensitive point-of-care testing (POCT) of cTnI using hierarchical dendritic copper-nickel (HD-nanoCu-Ni) nanostructures. The electrodeposited HD-nanoCu-Ni film (∼22 μm thick) on an ITO-coated glass substrate exhibits superior capillary action and structural integrity. These properties enable efficient sample transport and antibody immobilization, making it a compelling alternative to conventional multi-component paper-based LFIA test strips, which are often plagued by structural fragility and susceptibility to moisture damage. The biofunctionalized HD-nanoCu-Ni substrates were laser-etched with lateral flow channels, including a sample loading/conjugate release zone, a test zone, and a control zone. Numerical simulations were used to further optimize the design of these channels to achieve optimal fluid flow and target capture. The HD-nanoCu-Ni LFIA device utilizes a fluorescence quenching based sandwich immunoassay format using antibody-labeled gold nanoparticles (AuNPs) as quenchers. Two different fluorescent materials, fluorescein isothiocyanate (FITC) and CdSe@ZnS quantum dots (QDs), were used as background fluorophores in the device. Upon the formation of a sandwich immunocomplex with cTnI on the HD-nanoCu-Ni device, introduced AuNPs led to the fluorescence quenching of the background fluorophores. The total assay time was approximately 15 min, demonstrating the rapid and efficient nature of the HD-nanoCu-Ni LFIA platform. For FITC, both inner filter effect (IFE) and fluorescence resonance energy transfer (FRET) contributed to the AuNP-mediated quenching. In the case of CdSe@ZnS QDs, IFE dominated the AuNP-induced quenching. Calibration curves were established based on the relationship between the fluorescence quenching intensity and cTnI concentration in human serum samples, ranging from 0.5 to 128 ng/mL. The limits of detection (LODs) were determined to be 0.27 ng/mL and 0.40 ng/mL for FITC and CdSe@ZnS QDs, respectively. A method comparison study using Passing-Bablok regression analysis on varying cTnI concentrations in human serum samples confirmed the equivalence of the HD-nanoCu-Ni LFIA platform to a commercial fluorescence cTnI LFIA assay kit, with no significant systematic or proportional bias observed.

Green synthesis and characterization of Ag nanoparticles using fresh and dry Portulaca Oleracea leaf extracts: Enhancing light reflectivity properties of ITO glass

AbstractSilver (Ag) nanoparticles (NPs) are perceiving remarkable progress during the past few periods due to its exclusive properties in many applications. Recently, green synthesis method of NPs is racing against traditional chemical and physical methods by avoiding the use of many toxic chemicals, and expensive devices. Accordingly, in this study, dry and fresh Portulaca‐oleracea L. leaf extract has been employed for producing AgNPs as a reducing, capping and stabilizing agents. This process is simple, eco‐friendly and green. UV–vis spectra showed the formation of AgNPs represented by the change of a colorless liquid to brownish solution. The crystallinity of the AgNPs, was confirmed by X‐ray diffraction (XRD). The contribution of the available functional groups of the leaf extract in the reduction and capping process of NPs was demonstrated using Fourier transform infrared spectroscopy (FTIR). This study showed that fresh Portulaca‐oleracea L. leaf extract provides better NPs in terms of stability, purity, degree of crystallinity and spherical shape. The biosynthesized AgNPs from both procedures were coated on the indium tin oxide (ITO) glass substrates to enhance the reflectivity property. It has been shown that the utilized AgNPs, from fresh Portulaca‐oleracea L. extract, has smaller size and negligeable agglomeration, consequently lower light transmittance.

P3HT:ITIC polymer based photovoltaic biointerfaces for neural photostimulation

Aims/Purpose: Optoelectronic neural interfaces have diverse applications in comprehending neural network and treatment of neurodegenerative conditions especially in the field of the vision impairments. We aimed to use the non‐invasive, capacitive photocurrent generation stimulated by near‐infrared light in the biological environment integrating P3HT:ITIC devices to provide neuroprotective and neurodegenerative effects with reducing axonal damage through local repetitive photo‐stimulation.Methods: In this study, we performed neuron stimulation with the help of ITO/ZnO/P3HT:ITIC photoactive polymer implant placed on an indium tin oxide (ITO) glass. To evaluate the biocompatibility of the P3HT:ITIC devices, CTG cell viability and LDH leak assay were performed on primary nervous and visual system cells including Mio‐M1 and primary astrocytes. Cell specific biomarkers were examined by immunofluorescence staining to demonstrate short‐ and long‐term morphological changes and neural network improvements on both the biointerface and ITO control substrates.Results: We fabricated NIR‐responsive photovoltaic P3HT:ITIC biointerface with ZnO nanoparticles (NPs) as electron transport layer and P3HT:ITIC thin films as photoactive layer on ITO glass substrates. After evaluation of their stability, we showed that primary neurons, astrocytes and Müller glia cells on the biointerface have high cell viability, low cytotoxicity and preserved cellular network and morphology after 2 weeks of culture condition.Conclusions: Our study will provide novel solutions to existing problems in electrostimulation devices by exploring capabilities of wirelessly functional, biocompatible organic polymer‐based photoelectric devices with low cost of production. They have a potential in establishing a platform for the development of near infrared light‐controlled electrostimulation treatment, that can improve axonal healing in retina and optic nerve injuries.

Sensitive Recognition of Acetamiprid with a Unique Electrochromic Molecular Imprinted Polymer Sensor

The development of molecularly imprinted polymers (MIPs) and the applications for them have attracted a great deal of interest during the last two decades. MIPs are generally used in different fields, specially molecularly imprinted electrochemical sensors (MIECS), due to their particular design and specific detection abilities [1]. The advantages of an electrochemical MIP sensor include low cost, easy operation, rapid response time and excellent potential for miniaturization and construction for portable equipment applications [2]. In the scope of this work, we performed that electropolymerization of IrO2 as an electrochromic material on an indium tin oxide (ITO) glass substrate and electrosynthesis on this electrode using pyrrole as a functional monomer in the presence of acetamiprid as template were used to create the electrochromic molecular imprinted polymer sensor (MIP/IrO2/ITO). With the created electrochromic MIP sensor, it is intended to create a selective pesticide sensor by utilizing molecular imprinted polymer (MIP) technology, and to detect with the naked eye by color change depending on the acetamiprid concentration by using electrochromic material. The IrO2/ITO electrochromic film demonstrated magnificent cycle stability (100 cycles), high coloration efficiency (400 cm2 C-1 at 450 nm), and quick coloring/bleaching reaction time (8.60s/7.10s, respectively). By using in-situ spectroelectrochemical measurements, these optical properties of MIP/IrO2/ITO were obtained at various acetamiprid concentrations for quantitative analysis. By using differential pulse voltammetry between -0.2 V and +0.8 V (versus Ag/AgCl in 0.1 M PBS), the sensor performance of MIP/IrO2/ITO was assessed. In an acetamiprid concentration range of 4.29–38.6 nM, the MIP/IrO2/ITO electrode demonstrated linear response with a detection limit of 2.72 nM, sensitivity of 47.2 µA nM-1, and repeatability of 0.87%. Keywords: Electrochromism; Molecularly imprinted polymer (MIP); Pyrrole; IrO2;Acetamiprid; Electrochemical sensor; Spectroelectrochemistry. Acknowledgements This work was supported by The Scientific and Technological Research Council of Türkiye, TUBITAK (Project No:121Z784) as the financial.

Electrochromic molecular imprinted polymer sensor for detection of selective acetamiprid

An electrochromic molecular imprinted polymer sensor was constructed by electropolymerization of IrO2 as an electrochromic material on an indium tin oxide glass substrate and electrosynthesis on this electrode was achieved with pyrrole as a functional monomer in the presence of acetamiprid as a template. With the designed electrochromic MIP sensor, it was aimed to detect the color change of the electrochromic material with change in the acetamiprid concentration by the naked eye and to develop a selective pesticide sensor by molecular imprinted polymer technology. These optical characteristics of MIP/IrO2/ITO were determined with different acetamiprid concentrations for quantitative analysis by in-situ spectroelectrochemical measurements. The sensor performance of MIP/IrO2/ITO was determined with differential pulse voltammetry between −0.2 V and + 0.8 V (vs Ag/AgCl in 0.1 M phosphate buffer solution. MIP/IrO2/ITO electrode exhibited linear response with acetamiprid concentrations in the range of 4.29–38.6 nM with a detection limit of 2.72 nM, sensitivity of 47.2 μA nM−1 and reproducibility of 0.87 %.

Performances of Nano-Structured Cu2O Thin Films Electrochemically Deposited on ITO Substrates in Lactate Bath as Liquid Petroleum Gas Sensors

The investigations are focused on structural and surface morphological features and their influence on electrical and wetting characteristics against liquid petroleum gas (LPG) sensing of synthesized nanostructured cuprous oxide (Cu2O) thin films grown by electrochemical deposition (ECD) on indium tin oxide (ITO) glass substrates in lactate bath (pH 10). p-Cu2O films revealed a cubical-tetrahedron nano-scale polycrystalline grain distribution (average grain size: 64.2 nm, inter planer spacing: 0.24 nm) that exhibited dominance in the crystallographic plane (111). LPG sensing evaluations of p-Cu2O/ITO done at 70 °C constant temperature with 100% LPG at 5 cc min−1 flow rate, showed excellent gas sensor response, recovery, and stability over time due to its moderate wetting behavior (average contact angle: ∼86°). AC impedance measurements carried out at room temperature demonstrated an ionic to electronic conduction variation from 100 Hz to 1 MHz, due to adsorption/desorption of LPG molecules (CnH2n+2) and oxygen species on the nano-particles surface. Cu2O/ITO flat band potential was found to be higher than its’ ambient state after exposure to LPG with an increment in acceptor density. Overall, this efficient LPG sensing could be attributed to the interfacial properties of Cu2O thin films and ITO substrates, that provide an optimized fabrication process of nano-structured Cu2O thin films.

Reconfigurable perfect vortex beam generator based on a liquid crystal spiral phase plate.

A transmissive adaptable optical setup to generate a range of perfect vortex beams (PVBs) carrying different topological charges (TC) without using moving parts is presented. The setup is composed of an ad hoc transparent reconfigurable liquid crystal (LC) spiral phase plate (SPP), a refractive axicon and a convergent refractive lens. The LC SPP electrodes are manufactured ablating indium-tin oxide (ITO) glass substrates using direct laser writing (DLW) resulting in a very high fill factor device. In-house tailored electronics drive the 72 LC SPP electrodes giving rise to 72 different configurations with orbital angular momentum. In this work, the generation of PVBs with 36 positive or 36 negative TCs using this optical setup is accomplished.

Using Various Solvents for Extracting Grape Juice as Dye and Applying It in Fabrications of Dye-Sensitized Solar Cells

Using grape juice as a natural dye source and employing a solvent extraction to isolate anthocyanins and subsequently harnessing them as sensitizers, dye-sensitized solar cells (DSSCs) were fabricated in this study. The extraction process required diverse solvents, including tert-butanol, acetonitrile, acetone, and ethanol, with multiple adjustments and parameter optimizations to determine the most effective ratio in extraction. In the preparation of the photoanode, commercial titanium dioxide powder, which combined 20 mol% anatase phase and 80 mol% rutile phase, was utilized and applied through a doctor blade technique. The prepared photoanodes were immersed in the extracted anthocyanin dye and subjected to being exposed at various times to ensure complete light exclusion throughout the process. For electrode preparation, a platinum film approximately 1 nm thick was sputter-coated onto an indium tin oxide (ITO) glass substrate. The photoanodes treated in a dye-soaking process were then sealed with the electrodes. We measured incident photon-to-electron conversion efficiency (IPCE) with ultraviolet-visible spectroscopy (UV-VIS) and a solar simulator to comprehensively assess the performance of the manufactured dye-sensitized solar cells.

Fabrication and processing of bacterial cellulose/silver nanowire composites as transparent, conductive, and flexible films for optoelectronic applications

AbstractThis work reports on the engineering and fabrication of transparent, conductive, and flexible films made as a composite of bacterial cellulose microfibers (BMF), a polymer (either PVA or PEO), and silver nanowires (AgNWs) as viable and cost‐effective replacements to commercial indium‐tin oxide (ITO) and fluorine‐doped tin oxide (FTO) transparent conductors. The studies conducted indicate that the optical and mechanical properties of BMF‐polymer substrates are tuneable by varying the ratio of BMF to polymer. An optimized ratio of 70:30 of BMF to polymer was established for BMF‐PVA and BMF‐PEO composites. The optimized composite films were coated with varying amounts of AgNWs. As the AgNW loading increased, the deposition density of AgNW networks increased, while the sheet resistance and optical transmittance decreased. The optimum AgNW loading was determined at 0.20 mg for both composite films. The BMF‐PVA‐AgNW film displayed transmittance between 81% and 71% and an average resistivity of 9.462 ± 0.588 Ω/sq while the BMF‐PEO‐AgNW films showed transmittance between 73% and 65% and an average resistivity of 9.388 ± 0.1.375 Ω/sq. These properties compared well to that of commercial ITO and FTO glass substrates. The findings promote cellulose‐based composites as low‐cost, lightweight, and durable substrates for optoelectronic applications.

Enhanced Nanogenerator Performances of 1-D Al-Doped ZnO Nanorod Arrays through Ultrasonic Wave Systems

One-dimensional (1-D) well-aligned zinc oxide (ZnO) nanorods (NRs) without and with aluminum (Al) dopants were triumphantly grown on conductive indium–tin-oxide glass substrates through a simple chemical bath deposition at low temperature in this study. The designed devices are also called the AZO-0 and AZO-1 samples. After annealing in a vacuum state (10 min, 600 °C), the optical properties of the nanostructures were explored via photoluminescence emission spectroscopy. Field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and an X-ray diffraction spectrometer were used to investigate the surface nanostructures and crystalline properties of the NR arrays. It was seen that all nanostructures clearly showed a single-crystal property with hexagonal wurtzite shape and grew vertically on the substrate. The elemental content of the sample was checked by X-ray photoelectron spectroscopy and an energy-dispersive X-ray spectrometer. Additionally, nanogenerators (NGs) based on the 1-D AZO-0 and AZO-1 nanostructures were also fabricated and investigated. The copper tape was successfully utilized to combine nanostructures and electrodes for the NG device in an ultrasonic oscillator machine with a water chamber. As a result, it was found that the output power values of the AZO-1 NR NGs were higher than that of the AZO-0 NR NGs. The AZO-1 NRs revealed significantly superior conductive performance in NG devices and are promising candidates in future self-powered NG applications.

Analysis of morphological and electro-optical properties of silica nanoparticles induced vertically aligned liquid crystal - effect of doping and coating techniques

Conventionally, polyimide (PI) coating materials are used on the indium tin oxide (ITO) glass substrates to induce the vertical alignment (VA) of nematic liquid crystals (LCs). However, this coating technique requires a couple of steps such as spin coating, high-temperature baking and mechanical rubbing which limits their applicability to flexible LC display device applications. In the present work, VA of nematic LCs in a confined cell is induced using two different approaches: one via doping of silica nanoparticles (SNPs) as guest particles in LCs and the other with the deposition of SNPs layer on ITO glass substrates. Further, morphological and electro-optical (E-O) studies have been studied for the SNPs doped and SNPs coated vertically aligned liquid crystals (VALCs). The morphological study shows the identical degree of dark (black) and bright (white) textures of SNPs doped and coated VALC cells at OFF and ON states, respectively under the crossed polarizers. Also, the VA of nematic LC molecules in confined cells has been confirmed from the conoscopic behaviour. Consequently, morphological and E-O results revealed that the threshold (V th ) and operating (V o ) voltages required to switch the LCs from their initial VA (black state) towards minimum transition planar state and complete planar (bright) state, respectively, are reduced with better contrast ratio (CR) in SNPs coated VALC cell as compared with SNPs doped VALC cell.

Chronoamperometry-based controllable fabrication of gold nanoparticle monolayers and their hydrophobic force-induced movement on indium tin oxide glass substrate

Owing to their unique plasmonic properties, noble metals have been the materials of choice for photovoltaics, photocatalysis and sensors. Here, we demonstrate novel gold(Au) monolayers with tailorable particle diameters and optical property on transparent indium tin oxide (ITO) using a simple electrochemical deposition. The nanoparticles on ITO are spherical and isolated, and are identified as Au0 nanoparticles. The gold nanoparticles are uniformly distributed on ITO surface, but the gold nanoparticle sizes increase and the particle population densities decrease at lower current densities, resulting in higher light scattering. There is a positive correlation between mean particle size and maximum extinction wavelength of gold nanoparticles prepared with different current densities under a fixed total charge, whereas the maximum extinction wavelength of gold nanoparticles does not change with the total charge under the fixed current densities. The localized surface plasmon resonance change of Au nanoparticles on ITO can be effectively tuned by regulating deposition current density. With the existence of alkanethiols on Au monolayers surface, the original pink color of gold monolayers changed to blue after immersion in toluene for 30 min, indicating hydrophobic force produced by oil-in-water (O/W) or water-in-oil (W/O) phenomenon caused gold nanoparticles to migrate and produce a color change.

Two-dimensional Cs3Bi2I6Cl3 perovskite for resistive switching behaviors and artificial synaptic simulation

Two-dimensional Cs3Bi2I6Cl3 perovskite films have been successfully grown on indium tin oxide (ITO) glass substrates, which were used to fabricate the memory device with the structure of Al/Cs3Bi2I6Cl3/ITO. The current memristor exhibited bipolar resistive switching behaviors. Both the endurance and retention time tests clearly demonstrate the excellent stability of the present device. Moreover, the short-term plasticity of biological synapse was successfully simulated by evaluating the conductance responses of Al/Cs3Bi2I6Cl3/ITO device under applying various voltage pulses in detail. The enhancement of conductance triggered by 10 consecutive pulses (−0.5 V, 10 ms) was up to be around 40% compared to the resting conductance level. The simulations of long-term plasticity for biological synapse were also performed through spike-timing-dependent plasticity. The fitted time constants are 8.38 and 6.89 ms for long-term potentiation and long-term depression, respectively, which are comparable to the millisecond-scale response time in biological synapses. In addition, based on the photoelectric response ability, the current Al/Cs3Bi2I6Cl3/ITO device established associative learning behavior successfully by simulating the Pavlov’s dog experiment. The present Al/Cs3Bi2I6Cl3/ITO device is promising to be used for resistive switch and biological synaptic simulation of next generation memristors.

Template Free Anisotropically Grown Gold Nanocluster Based Electrochemical Immunosensor for Ultralow Detection of Cardiac Troponin I.

Anisotropic gold nanostructures have fascinated with their exceptional electronic properties, henceforth exploited for the fabrication of electrochemical sensors. However, their synthesis approaches are tedious and often require a growth template. Modern lifestyle has caused an upsurge in the risk of heart attack and requires urgent medical attention. Cardiac troponin I can serve as a biomarker in identification of suspected myocardial infection (heart attack). Hence the present work demonstrates the fabrication of a sensing platform developed by assimilating anisotropic gold nanoclusters (AuNCs) with anti cTnI antibody (acTnI) for the detection of cardiac troponin I (cTnI). The uniqueness and ease of synthesis by a template-free approach provides an extra edge for the fabrication of AuNC coated electrodes. The template-free growth of anisotropic AuNCs onto the indium tin oxide (ITO) glass substrates offers high sensitivity (2.2 × 10-4 A ng-1 mL cm-2) to the developed sensor. The immunosensor was validated by spiking different concentrations of cTnI in artificial serum with negligible interference under optimized conditions. The sensor shows a wide range of detection from 0.06-100 ng/mL with an ultralow detection limit. Thus, it suggests that the template-free immunosensor can potentially be used to screen the traces of cTnI present in blood serum samples, and the AuNCs based platform holds great promise as a transduction matrix, hence it can be exploited for broader sensing applications.

Growth of single-crystalline MAPbI3 perovskite film by a modified space-confined inverse temperature crystallization method

Single crystalline (SC) metal halide perovskite absorber film can outperform its polycrystalline counterpart in power conversion efficiency and stability due to the absence of grain boundaries. However, SC perovskite film's direct growth on charge selective contact layer coated substrates for solar cell applications is not widely explored. In this study, SC methylammonium lead iodide (MAPbI3) perovskite film is directly grown on charge selective (electron and hole transport) contact layer coated substrates (TiO2 coated fluorine doped tin oxide (FTO) glass substrate and poly(triarylamine) (PTAA) coated indium tin oxide (ITO) glass substrate) by inverse temperature crystallization (ITC) method. The PTAA/ITO substrate's hydrophobic nature led to faster ion migration and controlled nucleation, resulting in large-sized SC MAPbI3 perovskite film. X-ray diffraction of the MAPbI3/PTAA/ITO showed SC nature with diffraction from (200) and (400) planes, indicating that the film is majorly (100) oriented. The MAPbI3 film grown on TiO2/FTO is found to be relatively small in size (< 1 mm), majorly oriented in the (110) plane with diffraction also from other planes indicating polycrystalline nature. Long-term stability studies over 1500 h show that SC MAPbI3 films show more endurance to ambient conditions than polycrystalline MAPbI3. The growth time of 50 h was reduced to 30 h by employing antisolvent-assisted ITC, resulting in ultra-stable circular shaped films suitable for photovoltaic applications.

Boosting the photoelectrochemical performance of vertically aligned MoS2 nanosheets by Ag2S decoration

The effective heterojunction is a decisive factor in maximizing the photoelectrochemical (PEC) properties of two-dimensional (2D) MoS2. Herein, we demonstrated 2D MoS2 nanosheet/Ag2S as an efficient heterostructure for PEC applications. The MoS2 nanosheet/Ag2S heterostructures was fabricated in a controllable manner by metalorganic chemical vapor deposition of vertical 2D MoS2 nanosheets on indium tin oxide glass substrate, followed by Ag2S decoration. The 2D MoS2 nanosheet/Ag2S heterostructure showed significantly enhanced photocurrent compared with pristine MoS2 nanosheets, which was attributed to the efficient photo-generated carrier separation by the heterojunction effect and fast transfer of a carrier based on nanosheets. These results suggest one of the promising heterostructures of 2D MoS2 for various PEC applications.

Application of electrowetting on dielectric (EWOD) in drug release control and release-on-demand

In this paper, a novel application of electrowetting on dielectric (EWOD) systems in controlling drug release is introduced. The application of electric field in changing the wettability of a substrate has been investigated before, and the correlation between the surface wettability and drug release characteristics of drug-eluting constructs has been reported in the literature; however, the effects of electric field on controlling the drug release rate using EWOD phenomenon has not been investigated before. In this paper, changing the interfacial tension between the solid drug-eluting substrate and the liquid media using EWOD and the consequent change in the drug release was targeted. To this aim, an indium tin oxide (ITO) glass substrate was coated with Polydimethylsiloxane (PDMS), acting as the dielectric layer, and the dielectric layer was then coated with layers of Rhodamine B, a model drug, loaded polylactic-co-glycolic acid (PLGA), acting as the biocompatible drug-eluting layer. The wettability dependency of the substrate to direct current (DC) voltages was assessed, and applying 300 V made a significant change in the contact angle, demonstrating enhanced hydrophilic properties. The contact angle did not significantly change by a further increase in voltage, reaching a contact angle saturation. Subsequently, in an in-vitro drug release study, the cumulative drug release of drug-loaded substrates under various voltages was examined, and increasing the voltage by 300 V noticeably increased the drug release in the media. In addition, the dielectric thickness had a direct effect on the contact angle. Lowering PDMS (dielectric layer) thickness decreased the contact angle and enhanced drug release. The polarity of the EWOD setup did not affect the contact angle and the drug release. The release-on-demand process can further be optimized to lower the required voltage while enhancing the drug release rate. This study introduces a novel application of the EWOD phenomenon in drug delivery.

Fabrication of Tungsten Oxide/Graphene Quantum Dot (WO3@GQD) Thin Films on Indium Tin Oxide-Based Glass and Flexible Substrates for the Construction of Electrochromic Devices for Smart Window Applications

In the present study, we have prepared tungsten trioxide (WO3)/graphene quantum dot (GQD) thin films (WO3@GQD) on indium tin oxide (ITO)-based glass and flexible (polyethylene terephthalate, PET) substrates for smart window applications. Furthermore, electrochromic devices (ECDs) were fabricated using WO3 and WO3@GQD thin films as electrochromic layers on ITO-based glass and flexible PET substrates. The WO3-based ECDs on ITO glass substrates exhibited a coloration efficiency (C.E.) of 56 cm2/C, while an improved C.E. of 78 cm2/C was obtained for WO3@GQD (5 min)-based ECDs on ITO glass substrates. The improvement in C.E. may be attributed to the presence of the conductive GQD. The WO3@GQD (5 min)-based ECDs also showed good stability for up to 10000 cycles. After checking the effect of GQD in WO3@GQD (5 min)/ITO glass through comparison with WO3/ITO glass with a liquid electrolyte, WO3@GQD (5 min) was applied for flexible ECDs. The developed flexible ECDs exhibited that WO3@GQD (5 min) can be used as a potential electrochromic layer in developing flexible smart windows.

Synthesis of tungsten oxide films at low processing temperature and their electrochromic properties

Tungsten oxide films with electrochromic properties were prepared by spin coating WCl6 ethanol solution on indium tin oxide (ITO) glass and polyethylene terephthalate (PET) substrate, and followed heat treatment at 60–400 °C in air for 1 h. The films were characterized by X-ray powder diffraction, scanning electron microscopy, energy spectrum analysis, electrochemistry and ultraviolet–visible–near-infrared (UV–Vis–NIR) spectrophotometer. Tungsten oxide films with different components can be obtained at different heat treatment temperatures. With the increase of heat treatment temperature, the products gradually lose the crystal water from WO3·2H2O to WO3·H2O and finally to WO3. The as-prepared film has many tiny cracks, which is beneficial for effective electrolyte penetration. The tungsten oxide PET films also show good electrochromic properties, and the coloring and bleaching processes are consistent with that of tungsten oxide device. The treatment at low temperature is no damage to the substrate and maintains the flexibility of the films. The method provides a simple, low-cost and large-scale practical scheme for the flexible electrochromic films.