Indium Tin Oxide Etching Research Articles

Portable self-powered electrochemical aptasensing platform for ratiometric detection of mycotoxins based on multichannel photofuel cell

Self-powered electrochemical sensors based on photofuel cells have attracted considerable research interest because their unique advantage of not requiring an external electric source, but their application in portable and multiplexed targets assay is limited by the inherent mechanism. In this work, a portable self-powered sensor constructed with multichannel photofuel cells was developed for the ratiometric detection of mycotoxins, namely ochratoxin A (OTA) and patulin (PAT). The spatially resolved CdS/Bi2S3-modified photoanodes and a shared Prussian Blue cathode were integrated on an etched indium-tin oxide slide to fabricate the multichannel photofuel cell. The aptamers of OTA and PAT were covalently bonded to individual photoanode regions to build sensitive interfaces, and the specific recognition of analytes impaired the output performance of constructed PFC. Accordingly, ratiometric sensing of OTA and PAT was achieved by utilizing the output performance of a control PFC as a reference signal. This approach effectively eliminates the impact of light intensity on the accuracy of the detection. Under the optimal conditions, the proposed sensing chip exhibited linear ranges of 2.0–1000 nM and 5.0–500 nM for OTA and PAT, respectively. The detection limits (3 S/N) were determined to be 0.25 nM for OTA and 0.27 nM for PAT. The developed ratiometric sensing method demonstrated good selectivity and stability in the simultaneous detection of OTA and PAT. It was successfully utilized for the analysis of OTA and PAT real samples. This work provides a new perspective for construction of portable and ratiometric self-powered sensing platform.

A Broadband Photodetector Based on PbS Quantum Dots and Graphene with High Responsivity and Detectivity.

A high-efficiency photodetector consisting of colloidal PbS quantum dots (QDs) and single-layer graphene was prepared in this research. In the early stage, PbS QDs were synthesized and characterized, and the results showed that the product conformed with the characteristics of high-quality PbS QDs. Afterwards, the photodetector was derived through steps, including the photolithography and etching of indium tin oxide (ITO) electrodes and the graphene active region, as well as the spin coating and ligand substitution of the PbS QDs. After application testing, the photodetector, which was prepared in this research, exhibited outstanding properties. Under visible and near-infrared light, the highest responsivities were up to 202 A/W and 183 mA/W, respectively, and the highest detectivities were up to 2.24 × 1011 Jones and 2.47 × 108 Jones, respectively, with light densities of 0.56 mW/cm2 and 1.22 W/cm2, respectively. In addition to these results, the response of the device and the rise and fall times for the on/off illumination cycles showed its superior performance, and the fastest response times were approximately 0.03 s and 1.0 s for the rise and fall times, respectively. All the results illustrated that the photodetector based on PbS and graphene, which was prepared in this research, possesses the potential to be applied in reality.

A self-powered biosensing system based on triboelectric nanogenerator for rapid bacterial DNA detection

A self-powered biosensing system based on triboelectric nanogenerator (TENG) for bacterial DNA detection is invented and a vertical contact-separation TENG was designed to provide a steady power supply to a detection bioreactor. A carboxyl-functionalized capture probe was modified on etched indium tin oxide (ITO) glass, with which target bacterial DNA could be recognized. Meanwhile, multi-walled carbon-nanotubes (CNT)-modified signal probe was designed to amplify the detection signal due to its excellent electrical conductivity. The self-powered biosensing system could measure the variation in output voltage and be highly sensible with a low detection limit at 0.084 pM of target DNA. In addition, a mathematical model based on the Freundlich isotherm was built to simulate the DNA detection process, and it was feasible to simulate the calibration equation and detection range. A portable self-powered biosensing device was made by integrating miniaturized TENG and bioreactor in a 3D-printed mold, with which the presence of bacterial DNA could be instantly indicated by LED (light-emitting diode). This study provided a useful platform for quick bacterial DNA detection and paved the way for further development of pocket diagnosis with TENG-based biosensing systems.

Indium tin oxide etch characteristics using CxH2x+2(x=1,2,3)/Ar

For the next generation display devices, dry etching technique for indium tin oxide (ITO) used as a transparent electrode is required to obtain a highly anisotropic etch profile, and to decrease the dimensional loss after the etching. For the dry etching of ITO, the easy dry cleaning of etch byproducts attached to the chamber wall during the dry etching is also important. In this study, by using novel hydrocarbon gases mixed with Ar, such as ethane (C2H6) and propane (C3H8), the dry etch characteristics and the etch residue cleaning process have been investigated using an inductively coupled plasma etcher, and the results were compared with the conventionally investigated methane (CH4)-based gases, such as CH4 and CH4/H2 mixed with Ar. The result showed that the hydrogen in CH4/H2 both decreased the ITO etch rate, and decreased the etch selectivity over photoresist (PR). By using hydrogen-less hydrocarbon gas having the alkane structure, such as CxH2x+2 (x = 2, 3), both the ITO etch rate and the etch selectivity were increased with the increase of carbon in the alkane structure; therefore, the highest etch rate was observed for C3H8. In addition, with the increase of x in the carbon of CxH2x+2, less dimensional loss, more anisotropic etch profile, and lower surface roughness could be observed. During the etching, etch residues containing C, In, Sn, O, and H were accumulated on the chamber wall due to the low volatility of the etch byproducts; however, the etch residues formed by all three hydrocarbon gases could be successfully dry cleaned using H2/Ar plasmas through the formation of InCxHy(x < y), COx, and SnHx.

Thermodynamic Characterization of a Highly Transparent Microfluidic Chip with Multiple On-Chip Temperature Control Units

Indium tin oxide (ITO) is a functional material with great transparency, machinability, electrical conductivity and thermo–sensitivity. Based on its excellent thermoelectric performance, we designed and fabricated a multilayer transparent microfluidic chip with multiple sets of on–chip heating, local temperature measurement and positive on–chip cooling function units. Temperature control plays a significant role in microfluidic approaches, especially in the devices that are designed for bioengineering, chemical synthesis and disease detection. The transparency of the chip contributes to achieve the real–time observation of fluid flow and optical detection. The chip consists of a temperature control layer made with an etched ITO deposited glass, a PDMS (polydimethylsiloxane) fluid layer, a PDMS cooling and flow control layer. The performances of the ITO on–chip microheaters, ITO on–chip temperature sensors and two coolants were tested and analyzed in different working conditions. The positive on–chip heating and cooling were proved to be area-specific under a large temperature–regulating range. This PDMS–ITO–glass based chip could be applied to both temporal and spatial stable temperature–regulating principles for various purposes.

Synthesis of Ni-Doped ZnO Nanorod Arrays by Chemical Bath Deposition and Their Application to Nanogenerators

Nanogenerators (NGs) based on Ni-doped ZnO (NZO) nanorod (NR) arrays were fabricated and explored in this study. The ZnO films were grown on indium tin oxide (ITO) glass substrates, and the NZO NRs were prepared by the chemical bath deposition (CBD) method. The samples were investigated via field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) spectral analysis. The results showed that the growth of NRs presented high-density single crystalline structures and were preferentially oriented in the c-axis direction. The optical characteristics of the NZO NRs were also measured by photoluminescence (PL) spectra. All samples exhibited two different emissions, including ultraviolet (UV) and green emissions. ITO etching paste was used to define patterns, and an electrode of Au film was evaporated onto the ITO glass substrates by the electron beam evaporation technique to assemble the NG device. In summary, ZnO NRs with Ni dopant (5 mM) showed significantly excellent performance in NGs. The optimal measured voltage, current, and power for the fabricated NGs were 0.07 V, 10.5 µA, and 735 nW, respectively.

Characterization of nanogenerators based on S-doped zinc oxide nanorod arrays

Nanogenerators (NGs) synthesized with sulfur (S) doped zinc oxide (ZnO) nanorods (NRs) by a hydrothermal method were characterized for their performances in this study. The NG formation steps consist of (1) growing the S-doped ZnO NRs on an indium-tin-oxide (ITO) glass substrate, (2) employing an ITO etching paste to create the electrode pattern, and (3) depositing an electrode of aluminum (Al) film on the ITO glass substrate by a radio-frequency magnetron sputtering technique for the final NG assembly. As found, the ZnO NRs doped with 5 at.% S exhibit the best efficiency among all S-doped ZnO NRs, with the optimal operational outputs of 150 mV, 0.16 μA, and 24 nW, respectively.

Electrochemical and Thermal Etching of Indium Tin Oxide by Solid-State Hybrid Organic–Inorganic Perovskites

We show that tin-doped indium oxide (ITO) can be thermally etched by the Bronsted acid salts methylammonium iodide (MAI), methylammonium lead triiodide (MAPbI3), and formamidinium lead triiodide (FAPbI3) in solid-state films and devices at common processing temperatures. More importantly, a series of reactions within an ITO/hybrid perovskite/Au device can be electrochemically induced near room temperature by applied cathodic voltages as low as −1.2 V. Cyclic voltammetry in this range leads to eventual In3+ leaching into the perovskite layer in the form of InI3, unambiguously identified by a binding energy signature of 445.9–446.3 eV measured by X-ray photoelectron spectroscopy. Furthermore, the etching is exacerbated by defects generated by O2-plasma treatment of the ITO compared to UV-ozone cleaning, lowering the reaction potential and the electrochemical stability window of an ITO/MAPbI3/Au device. Low-temperature, electrochemical reactivity at this interface has implications on operational stability, f...

Fabrication of Enzymatic Biofuel Cell with Electrodes on Both Sides of Microfluidic Channel

Enzymatic biofuel cells (EBFCs) that utilize glucose as fuel in a human body to produce electricity are being explored as promising alternatives to power implantable devices. However, some limitations need to be overcome to render such micro-electronic devices practically applicable. Here, we propose a microfluidic EBFC architecture with electrodes on both sides of the microchannel and its fabrication via stencil method. Multiwalled carbon nanotube (MWCNT) electrodes are fabricated on both sides of a Y-shaped microfluidic channel to reduce the effect of the depletion boundary layer and cross-diffusional mixing of the fuel and oxidant, which are functions of the distance from the microchannel inlet. Therefore, the microchannel length is reduced by half, while maintaining the same MWCNT electrode area. The microchannel is produced by polydimethylsiloxane (PDMS) casting whereas the electrodes are fabricated by a PDMS stencil, using MWCNT patterned on etched indium tin oxide glass. The electrodes are modified with glucose oxidase and laccase via direct covalent bonding. The cell performance is studied at different microchannel heights and flow rates, obtaining a maximum power and current density of 153 µW cm−2 and 450 µA cm−2, respectively, at a microchannel height of 450 µm and flow rate of 25 mL h−1. The double-layer EBFC shows a 23% improvement in the performance compared to a single-layer EBFC.

Comparative study of macroporous silicon-based photovoltaic characteristics using indium tin oxide‑silicon and pn‑silicon junction based devices

We report highly ordered macroporous silicon (Si)-based photovoltaic characteristics using indium tin oxide (ITO)/n-Si and pn-Si junction-based devices. The detailed fabrication processes including new controlled ITO etching are presented. Theoretical device simulations are performed to understand the presented device structures and propose an optimum device design based on processing limitations. The performance of ITO/n-Si junction devices directly depends on the conformal ITO coating along the pore surface. While pn-Si junction device requires additional doping step, the device can overcome the limitation of ITO conformal coating, especially for a device with high-aspect-ratio macropore structures. Experimental results also support the simulation analysis. The three-dimensional structural properties of well-defined macroporous Si coupled with the formation of photovoltaic devices are attractive for multi-functional applications.

Selective recovery of pure copper nanopowder from indium-tin-oxide etching wastewater by various wet chemical reduction process: Understanding their chemistry and comparisons of sustainable valorization processes

Sustainable valorization processes for selective recovery of pure copper nanopowder from Indium-Tin-Oxide (ITO) etching wastewater by various wet chemical reduction processes, their chemistry has been investigated and compared. After the indium recovery by solvent extraction from ITO etching wastewater, the same is also an environmental challenge, needs to be treated before disposal. After the indium recovery, ITO etching wastewater contains 6.11kg/m3 of copper and 1.35kg/m3 of aluminum, pH of the solution is very low converging to 0 and contain a significant amount of chlorine in the media. In this study, pure copper nanopowder was recovered using various reducing reagents by wet chemical reduction and characterized. Different reducing agents like a metallic, an inorganic acid and an organic acid were used to understand reduction behavior of copper in the presence of aluminum in a strong chloride medium of the ITO etching wastewater. The effect of a polymer surfactant Polyvinylpyrrolidone (PVP), which was included to prevent aggregation, to provide dispersion stability and control the size of copper nanopowder was investigated and compared. The developed copper nanopowder recovery techniques are techno-economical feasible processes for commercial production of copper nanopowder in the range of 100–500nm size from the reported facilities through a one-pot synthesis. By all the process reported pure copper nanopowder can be recovered with>99% efficiency. After the copper recovery, copper concentration in the wastewater reduced to acceptable limit recommended by WHO for wastewater disposal. The process is not only beneficial for recycling of copper, but also helps to address environment challenged posed by ITO etching wastewater. From a complex wastewater, synthesis of pure copper nanopowder using various wet chemical reduction route and their comparison is the novelty of this recovery process.

In-situ characterization of electrochromism based on ITO/PEDOT:PSS towards preparation of high performance device**Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA034201) and the Chinese Universities Scientific Fund (Grant No. 2015LX002).

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is usually sandwiched between indium tin oxide (ITO) and a functional polymer in order to improve the performance of the device. However, because of the strong acidic nature of PEDOT:PSS, the instability of ITO/PEDOT:PSS interface is also observed. The mechanism of degradation of the device remains is unclear and needs to be further studied. In this article, we investigate the in-situ electrochromism of PEDOT:PSS to disclose the cause of the degradation. X-ray photoelectron spectroscopy (XPS) was used to characterize the PEDOT:PSS films, as well as the PEDOT:PSS plus polyethylene glycol (PEG) films with and without indium ions. The electrochromic devices (ECD) based on PEDOT:PSS and PEG with and without indium ions are carried out by in-situ micro-Raman and laser reflective measurement (LRM). For comparison, ECD based on PEDOT:PSS and PEG films with LiCl, KCl, NaCl or InCl3 are also investigated by LRM. The results show that PEDOT:PSS is further reduced when negatively biased, and oxidized when positively biased. This could identify that PEDOT:PSS with indium ions from PEDOT:PSS etching ITO will lose dopants when negatively biased. The LRM shows that the device with indium ions has a stronger effect on the reduction property of PEDOT:PSS-PEG film than the device without indium ions. The contrast of the former device is 44%, that of the latter device is about 3%. The LRM also shows that the contrasts of the device based on PEDOT:PSS+PEG with LiCl, KCl, NaCl, InCl3 are 30%, 27%, 15%, and 18%, respectively.

Commercial process for the recovery of metals from ITO etching industry wastewater by liquid–liquid extraction: simulation, analysis of mechanism, and mathematical model to predict optimum operational conditions

A commercial process for the recovery of metals from the indium-tin-oxide (ITO) etching industry wastewater by liquid–liquid extraction has been developed.

Nanoparticle and nanosphere mask for etching of ITO nanostructures and their reflection properties

Au nanoparticles and polystyrene nanospheres were used as mask for plasma etching of indium tin oxide (ITO) layer. By reactive ion etching (RIE) processes, the morphology of polystyrene nanospheres can be tuned through chemical or physical etching, and Au nanoparticle mask can result in ITO nanostructures with larger aspect ratio than nanosphere mask. During inductively coupled plasma (ICP) processes, Au nanoparticle mask was not affected by the thermal effect of plasma, whereas temperature of the substrate was essential to protect nanospheres from the damaging effect of plasma. Physical bombardment in the plasma can also modify the nanospheres. It was observed that under the same process conditions, the ratio of CH4 and H2 in the process gas can affect the etching rate of ITO without completely etching the nanospheres. The morphology of ITO nanostructures also depends on process conditions. The resulting ITO nanostructures show lower reflection in a spectral range of 400–1000 nm than c-Si and conventional antireflection layer of SiNx film. ITO nanostructures obtained after etching (scale bar = 200 nm).

Study of wet etching thin films of indium tin oxide in oxalic acid by monitoring the resistance

We describe a study on wet etching of thin films of indium tin oxide (ITO) using a simple method by monitoring the resistance of the thin film in aqueous solutions of oxalic acid and hydrochloric acid. Generally three different regimes can be distinguished during etching ITO in acids: (1) initial etching, which is slow, (2) a fast etching phase and (3) slow etching stage at the end. These regimes are explained in terms of a porosity–roughness model. This porosity model has been confirmed largely by X-ray reflection measurements at grazing incidence, roughness measurements and scanning electron microscopy (SEM).A reliable method for monitoring the resistance during etching has been developed. This method is based on a 2-strips measuring jig with a very low series contact resistance.The activation energy of the etch rate of ITO films was found to be 80±5kJ/mol for oxalic acid and 56±5kJ/mol for HCl. SEM analyses in the final stage of the etching process indicate an enrichment of Sn in the residual film material. These observations are explained in terms of preferential etching of In2O3. X-ray analyses showed that the density of the ITO film decreased by etching. By adding ferric chloride to the oxalic acid solution we could accelerate the etch rate substantially.

From bipolar to quadrupolar electrode structures: an application of bond-detach lithography for dielectrophoretic particle assembly.

We describe a new, simple process for fabricating transparent quadrupolar electrode arrays enabling large-scale particle assembly by means of dielectrophoresis. In the first step, interdigitated electrode arrays are made by chemical wet etching of indium tin oxide (ITO). Then, the transition from a bipolar to a quadrupolar electrode arrangement is obtained by covering the electrode surface with a thin poly(dimethylsiloxane) (PDMS) film acting as an electrical insulation layer in which selective openings are formed using bond-detach lithography. The PDMS insulating layer thickness was optimized and controlled by adjusting experimental parameters such as the PDMS viscosity (modulated by the addition of heptane) and the PDMS spin-coating velocity. The insulating character of the PDMS membrane was successfully demonstrated by performing a dielectrophoretic assembly of polystyrene particles using interdigitated electrodes with and without a PDMS layer. The results show that the patterned PDMS film functions properly as an electrical insulation layer and allows the reconfiguration of the electric field cartography. Electric field simulations were performed in both configurations to predict the dielectrophoretic behavior of the particles. The simulation results are in perfect agreement with experiments, in which we demonstrated the formation of concentrated clusters of polystyrene particles and living cells of regular size and shape.

Indium Recovery by Selective Removal of Copper and Tin from ITO Etching Waste Solution by Cementation with Cobalt and Subsequent Electro-Winning: A Validation Experiment

AbstractA three-step batch-type indium recovery method was developed to prove feasibility of recovering indium powders from highly acidic dilute indium chloride solution prepared by dissolving indium tin oxide (ITO) electrodes of waste liquid crystal display (LCD) panels in concentrated hydrochloric acid (HCl) solutions. More specifically, a batch-type three-step indium recovery by cementation and subsequent electro co-deposition process was designed and performed and its individual experimental parameters were varied to get insights in the engineering feasibility of validation experiments. Significant proportion of copper and tin was removed by cementation with cobalt powder. Residual copper and tin ions were further removed by primary electro co-deposition directly from the highly acidic etching waste solution recovered from cementation process. Synergistic effect of cobalt electro co-position on indium electro-reduction was observed during secondary electro co-deposition, which warrants additional electro-refining process for selective removal of indium from cobalt-indium metal mixture and its purification. Ionic and metallic species thus obtained from the validation experiments were further characterized using various analytical tools such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES), X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray fluorescence (XRF).

A real-time microfluidic multiplex electrochemical loop-mediated isothermal amplification chip for differentiating bacteria

This report shows that loop-mediated isothermal amplification (LAMP) of nucleic acid can be integrated on a laser etched indium tin oxide (ITO) electrode-based multiplex microfluidic chip for real-time quantitative differentiation of bacteria; we call this technique microfluidic multiplex electrochemical LAMP (μME-LAMP) system. Three important acute upper respiratory tract infections (URTI) related bacteria, namely Mycobacterium tuberculosis (MTB), Haemophilus influenza (HIN), and Klebsiella pneumonia (KPN) were chosen for this study. We monitored the amplification process by measuring and analyzing the electrochemical signal of methylene blue (MB) through eight etched ITO electrochemical reactors. The results indicated that this assay with the ability of analyzing multiple genes qualitatively and quantitatively is highly specific, operationally simple, and cost/time effective. It exhibits high sensitivity with detection limits of 28, 17, and 16copiesμL−1 for MTB, HIN, and KPN, respectively. The whole differentiation can be finished in a short time of 45min, which has the potential to apply in clinical diagnosis.

Improving the Stability of Bulk Heterojunction Solar Cells by Incorporating pH-Neutral PEDOT:PSS as the Hole Transport Layer

In the application of traditional bulk heterojunction polymer solar cells, to prevent the etching of ITO by the acidic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and thereby improve the device stability, pH-neutral PEDOT:PSS is introduced as the hole transport layer (HTL). After treating the neutral PEDOT:PSS with UV-ozone and with an oxygen plasma, the average power conversion efficiency (PCE) of the device increases from 3.44% to 6.60%. Such surface treatments reduce the energy level offset between the HTL and the active layer, which increases the open circuit voltage and enhances hole transportation, leading to the PCE improvement. Moreover, the devices with the neutral PEDOT:PSS HTL are more stable in air than those with the acidic PEDOT:PSS HTL. The PCE of the devices with the acidic PEDOT:PSS HTL decreases by 20% after 7 days and 45% after 50 days under ambient conditions, whereas the PCE of the devices with the pH-neutral PEDOT:PSS HTL decreases by only 9 and 20% after 7 and 50 days, respectively. X-ray photoelectron spectroscopy shows that the acidic PEDOT:PSS etches the indium from the indium-tin-oxide (ITO) electrode, which is responsible for the degradation of the device. In comparison, the diffusion of the indium is much slower in the devices with the pH-neutral PEDOT:PSS HTL.

Enhanced thermal stability of organic solar cells on nano structured electrode by simple acid etching

The long-term thermal stability of organic photovoltaic device has been emerged as a crucial characteristic to satisfy the demand of industry requiring lifespan of 20year. In this paper, etched indium–tin-oxide (ITO) nanoelectrodes are employed to enhance the thermal stability and power conversion efficiency in poly(3hexylthiophene):methanofullerene bulk-heterojunction solar cells. A simple etching process for the ITO electrode was carried out using a hydrochloric acid solvent in order to significantly increase the roughness of the ITO surface. This nanostructured ITO not only induced efficient light harvesting, but also acted as a barrier that suppressed the PCBM phase separation, resulting in the lifespan increased from 33h to 77h during thermal annealing.