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A sensitive and portable on-thread pre-concentration and colorimetric detection method of copper ions was proposed. Commercial cotton thread was proposed as a solid sorbent for effectively extracting copper ions (Cu2+) from solution. The adsorbed Cu2+ was converted to Cu+ by ascorbic acid. The Cu+ on the threads was visualized by horseradish-peroxidase-catalyzed color changes of a chromogenic oxidized tetramethylbenzidine substrate. The adsorption of Cu2+ on the plasma- and Na2CO3-treated thread was verified by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and zeta potential characterization. The Cu+-induced dysfunction of HRP on the thread was verified by X-ray photoelectron spectroscopy. With optimized reaction conditions, the concentration-dependent colorimetric response plot was characterized, where the linear detection range was 2–400 nM and the detection limit was about 0.15 nM. Measurements of a group of possible interfering ions and spiked real-water samples demonstrated the good selectivity of the proposed method. The proposed on-thread pre-concentration and colorimetric detection offers a low-cost and effective alternative for detecting of copper ions in real applications.

Cotton thread has been proposed as a new, economically affordable material for the fabrication of microfluidic circuits for use in fast, low-cost, point-of-care diagnostic testing devices. In this work, chitosan, a biocompatible polymer, was used to modify cotton thread to improve its fluidic properties for microfluidic applications. Electrostatic-interaction-mediated adsorption of chitosan on alkaline-scoured thread can effectively increase thread’s solution hydrophilicity and wicking rate. Moreover, the proposed process conserves the thread’s hydrophilicity and fluidic properties even when stored for several months. As a microfluidic platform for enzymatic-reaction-associated colorimetric measurement, the suggested chitosan modification results in the accumulation of more analyte in the detection zone because of the improved flow rate, which enhances the colorimetric signal intensity. In this study, a glucose oxidase-mediated colorimetric glucose assay was demonstrated on a chitosan-modified microfluidic thread-based analytical device (μTAD). A linear range of 1–7.5 mM, a low detection limit of 0.2 mM, and a recovery rate between 93 and 98% was achieved in detecting glucose in artificial urine samples.

CoSb3 thermoelectric thin films were prepared on polyimide flexible substrate by radio frequency (RF) magnetron sputtering technology using a cobalt antimony alloy target. Ti and In were added into CoSb3 thin films by co-sputtering. The influence of Ti and In on the thermoelectric properties of CoSb3 thin films was investigated. X-ray diffraction result shows that the major diffraction peaks of all the thin films match the standard peaks related to the CoSb3 phase. The sample has best thermoelectric properties when the Ti sputtering time was 1min and In sputtering time was 30 seconds.

In this study, copper selenide thin films were fabricated by ion beam sputtering deposition by using a fan-shaped target of Cu and Se. The influence of heat treatment on thermoelectric properties of copper selenide thin films was investigated. X-ray diffraction results demonstrate that the as-deposited and annealed thin films are both amorphous. The SEM images show that the thin films are discontinuous and just like island structure. The thin films are crystalline when the substrate temperature is added at the deposition process. The thin film exhibits the dominating CuSe phase at the substrate temperature of 250 °C and it transforms to single CuSe2 phase at the temperature of 300 °C. When the substrate temperature further increased to 350 °C, the mixed Cu2−xSe phase is dominated. The thin film with Cu2−xSe phase has a high electrical conductivity of 2.02 × 104 Scm−1 at 423 K and thin film with CuSe2 phase has a high Seebeck coefficient of 37.3 μVK−1 at 316 K.

Delafossite-type CuCr1−x Zn x O2 (x = 0, 0.03, 0.05, 0.07, 0.1) conductive oxides were synthesized by sol–gel method, and the effects of Zn-doping on morphology, structure, and electrical properties of the CuCr1−x Zn x O2 oxides were investigated. Based on X-ray diffraction (XRD) and Raman spectrum, the crystalline quality of the oxides is improved by the suitable substitution of Cr by Zn. The X-ray photoelectron spectroscopy (XPS) spectra reveal the chemical state of Zn is +2. The Hall and Seebeck coefficients of the pellet samples display a positive sign, indicating p-type conductive characteristics of the obtained oxides. The temperature-dependent resistivity of the oxides is proven to be consistent with small polaron hopping. For the three oxide samples with x = 0, 0.05, and 0.1, the activation energies for the polaron hopping between Zn2+ and Cr3+ sites are 54, 41.5, 32 meV, respectively, which is found to decrease with the increase of Zn content. The electrical conductivity can be remarkably improved by Zn-doping due to the small polaron hopping activation energy. These properties render this material promising as transparent electrode in optoelectronic industry.

Epitaxial thin films of CuFe 1 − x Sn x O 2 ( x = 0.00, 0.01, 0.03, 0.05, 0.07), a transparent oxide semiconductor with delafossite structure, were grow on Al 2 O 3 (0 0 0 1) substrate by sol–gel method, The X-ray diffraction patterns revealed that the CuFeO 2 film annealed at 500 °C in air was mainly composed of amorphous phase, and after post-annealed at 900 °C in N 2 , single phase CuFe 1 − x Sn x O 2 films with high c -axis oriented were obtained. The Raman spectrum confirmed the delafossite structure of the films. The binding energy of Cu-2p 3/2 , Fe-2p 3/2 and Sn-3d 5/2 were 932 eV, 711.3 eV and 486.2 eV in CuFe 1 − x Sn x O 2 films. The chemical composition of the films was close to its stoichiometry, which was determined by X-ray photoelectron spectroscopy. The films show high transmittance around 45–78% in the visible band and 78–95% in the near infrared spectral region, while the energy gaps for direct allowed transition were estimated as 3.5 ± 0.02 eV. The p-type characteristics of CuFe 1 − x Sn x O 2 thin films were determined by positive Hall coefficients. The resistivity of the film was 36.83 Ω cm for CuFeO 2 film at room temperature, significantly decreased to 1.043 Ω cm after substituting Sn 2+ for Fe 3+ . The resistivity showed a decrease at the beginning and increased with the growing of Sn ion doping ratio. These results demonstrate that the high c -axis oriented CuFe 1 − x Sn x O 2 films can be the very promising p-type transparent conductive thin films.

As an important wide bandgap p-type conductive delafossite material, CuScO2 (CSO) has been intensively investigated for its wide applications in multi-functional optoelectronic devices. In order to obtain both high infrared (IR) transparency and low resistivity, we report on, for the first time, the experimental preparation of single phase epitaxial CSO thin film by using polymer-assisted-deposition (PAD) method. As a key point in the PAD process, the used polymer materials (PEI and EDTA) not only control the desired viscosity for the process, but also bind the metal ions to prevent premature precipitation and formation of metal oxide oligomers. The technique results in a homogeneous distribution of the metal precursors in the solution as well as the formation of uniform metal organic film. Due to the uniaxial locked epitaxy mechanism, the epitaxial growth of CSO (0001) thin film on a-plane sapphire is achieved, and the orientation relationship of the film with respect to the substrate are confirmed to be CSO[3R](0001)//a-Al2O3(110). The obtained CSO thin film from the PAD technique exhibits a low electrical resistivity of 1.047 Ω cm at room temperature, and a high transmittance of 65–85% in the near-IR range and more than 85% in the mid-IR range. The presented technique does provide the possibility of preparing high-crystallinity oxide films which can be applicable over a wide wavelength range from visible band to infrared band.

In this study, we investigated the effect of carbon nanotubes (CNTs) and performance of the prepared membranes. Thin film composite (TFC) forward osmosis (FO) membranes were fabricated based on the polyacrylonitrile (PAN) substrate, incorporating carbon nanotubes (CNTs) in the active skin layer. The CNTs can improve the water flux through added the hydrophilic groups. The mean surface roughness and hydrophilicity increased with the concentration of carbon nanotubes increased. The TFC membranes incorporated CNTs (0.2 wt%) exhibited the best FO performance with water flux of 25.14 L/m2·h and reverse salt flux of 8.64 g/m2·h using 0.5 M NaCl as draw solution and DI water as feed solution during FO test. The research provides us a promising approach to fabricate the high flux FO membranes.

Transparent conductive IWO/Cu/IWO (W-doped In2O3) films were deposited on quartz substrates by magnetron sputtering of IWO and Cu in the Ar atmosphere. The X-ray diffraction (XRD) patterns identified the cubic iron&ndash, manganese ore crystal structure of the IWO layers. The influence of the thickness of the intermediate ultra-thin Cu layers on the optical and electrical properties of the multilayer films was analyzed. As the Cu layer thickness increases from 4 to 10 nm, the multilayer resistivity gradually decreases to 4.5 &times, 10&minus, 4 &Omega, &middot, cm, and the optical transmittance in the mid-infrared range increases first and then decreases with a maximum of 72%, which serves as an excellent candidate for the mid-infrared transparent electrode.