Galinstan has the potential to replace mercury - one of the most popular liquid metals. However, the easy oxidation of Galinstan restricts wide applicability of the material. In this paper, we report an effective reduction method for the oxidized Galinstan using gas permeable PDMS (polydimethlysiloxane)-based microfluidic channel. The complete study is divided into two parts - reduction of Galinstan oxide and behavior of reduced Galinstan oxide in a microfluidic channel. The reduction of Galinstan oxide is discussed on the basis of static as well as dynamic angles. The contact angle analyses help to find the extent of reduction by wetting characteristics of the oxide, to optimize PDMS thickness and to select suitable hydrochloric acid (HCl) concentration. The highest advancing angle of 155° and receding angle of 136° is achieved with 200 μm thick PDMS film and 37 wt% (weight percent) HCl solution. The behavior of reduced Galinstan oxide is analyzed in PDMS-based coplanar microfluidic channels fabricated using a simple micromolding technique. Galinstan in the microfluidic channel is surrounded by another coplanar channel filled with HCl solution. Due to the excellent permeability of PDMS, HCl permeates through the PDMS wall between the two channels (interchannel PDMS wall) and achieves a continuous chemical reaction with oxidized Galinstan. A Lab VIEW controlled syringe pump is used for observing the behavior of HCl treated Galinstan in the microfluidic channel. Further optimization of the microfluidic device has been conducted to minimize the reoxidation of reduced Galinstan oxide in the microfluidic channel.

Easy movement of oxidized Galinstan in microfluidic channels is a promising way for the wide application of the non-toxic liquid metal. In this paper, two different surface modification techniques (physical and chemical) are reported, which dramatically improve the non-wetting characteristics of oxidized Galinstan in the microfluidic channel. In the physical technique, normal paper textures are transferred to the inner wall of polydimethylsiloxane (PDMS) channels and four types of nanoparticles are then coated on the surface of the wall for further improvement of the non-wetting characteristics. Highest advancing angle of 167° and receding angle of 151° are achieved on the paper-textured PDMS with titanium oxide (TiO2) nanoparticles. In the chemical technique, three types of inorganic acids are employed to generate dual-scale structures on the PDMS surface. The inner wall surface treated with sulfuric acid (H2SO4) shows the highest contact angle of 167° and a low hysteresis of ~14° in the dynamic measurement. Creating, transporting, separating and merging of oxidized Galinstan droplets are successfully demonstrated in the fabricated PDMS microfluidic channels. After optimization of these modification techniques, the potential application of tunable capacitors and electronic filters is realized by using liquid metal-based microfluidic devices.

We report the morphology-controlled synthesis of aluminium (Al) doped zinc oxide (ZnO) nanosheets on Al alloy (AA-6061) substrate by a low-temperature-solution growth method without using any external seed layer and doping process.

This paper reports on the fabrication and characterization of ZnO based vertically integrated nanogenerator (VING) devices under controlled compression. The basic NG structure is a composite material integrating hydrothermally grown vertical piezoelectric zinc oxide (ZnO) nanowires (NWs) into a dielectric matrix (PMMA). A specific characterization set-up has been developed to control the applied compression and the perpendicularity of the applied force on the devices. The role of different fabrication parameters has been evaluated experimentally and compared with previously reported theoretical models, including the thickness of the top PMMA layer and the density of the NWs array in the matrix. Finally, the performance of the VING structure has been evaluated experimentally for different resistive loads obtaining a power density of 85 μW cm −3 considering only the active layer of the device. This has been compared to the performance of a commercial bulk layer of PZT (25 μW cm −3 ) under the same applied force of 5 N.

The present work discusses and compares the toluene sensing behavior of polyaniline (PANI) and graphene/polyaniline nanocomposite (C-PANI) films. The graphene–PANI ratio in the nanocomposite polymer film is optimized at 1:2. For this, N-methyl-2-pyrrolidone (NMP) solvent is used to prepare PANI-NMP solution as well as graphene-PANI-NMP solution. The films are later annealed at 230 °C, characterized using scanning electron microscopy (SEM) as well Fourier transform infrared spectroscopy (FTIR) and tested for their sensing behavior towards toluene. The sensing behaviors of the films are analyzed at different temperatures (30, 50 and 100 °C) for 100 ppm toluene in air. The nanocomposite C-PANI films have exhibited better overall toluene sensing behavior in terms of sensor response, response and recovery time as well as repeatability. Although the sensor response of PANI (12.6 at 30 °C, 38.4 at 100 °C) is comparatively higher than that of C-PANI (8.4 at 30 °C, 35.5 at 100 °C), response and recovery time of PANI and C-PANI varies with operating temperature. C-PANI at 50 °C seems to have better toluene sensing behavior in terms of response time and recovery time.

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A nanostructured copper (II) oxide film deposited by reactive DC-magnetron sputtering technique, has been studied for static sensor response towards methanol and ethanol by operating temperature and analyte concentration modulations. The optimum operating temperature (T opt) for the sensing of methanol and ethanol is observed to be 350 ˚C and 400 ˚C, respectively. The maximum sensitivity observed for 2500 ppm methanol and ethanol is 29% and 15.4% respectively. Another important observation is that the sensitivity time reduces with analyte concentrations, where as recovery time increases. The response time of 2500 ppm methanol and ethanol is 235 s and 247 s correspondingly. Index term: Copper (II) Oxide thin films, sputtering, gas sensing, response time and recovery time.

A novel flexible alloy substrate (Phynox, 50 µm thick) is used for the synthesis of Zinc Oxide (ZnO) nanorods by low-temperature solution growth method. The growth of ZnO nanorods were observed at low temperature range of 60-90 °C for the growth duration of 4 hours. As-synthesized nanorods were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) for their morphology, crystallanity, microstructure and composition. The as-grown ZnO nanorods were observed to be relatively vertical to the substrate. However, the morphology of ZnO nanorods in terms of their length, diameter and aspect ratio is found to vary with the growth temperatures. The morphological variations are mainly due to the effects of varied relative growth rates with growth temperature. The growth temperature influenced ZnO nanorods are also used for analyzing their wetting (either hydrophobic or hydrophilic) property. After carrying out multiple wetting behaviour analysis, it has been found that the as-synthesized ZnO nanorods are hydrophobic in nature. These ZnO nanorods have the potential application possibilities in self cleaning devices, sensors & actuators as well as energy harvesters like nanogenerators.Zinc Oxide (ZnO) is one of the most promising potential materials due to its remarkable properties such as wide band-gap (3.37eV), large exciton binding energy (60 meV), excellent chemical & thermal stability, transparency and biocompatibility. Due to the possible utilization of the above mentioned properties in various fields like electronics, optoelectronics, electrochemical and electromechanical, the ZnO has become more popular and drawing increasing interest in the area of nanotechnology [1][2][3][4]. ZnO is very flexible functional material exhibiting wide structural morphologies, such as nanocombs [5], nanorings [6], nanohelixes/nanosprings [7], nanobelts [8], nanowires/nanorods [9, 10], nanotubes [11], nanocages [12] and nanosheets [13]. Among these, one dimensional (1D) ZnO nanorords/nanowires have been extensively studied in the recent past due to their multifunctional device applications in the areas of ultraviolet (UV) lasers [14-15], light emitting diodes [16], field emission devices [17-18], solar cells [19-20], surface acoustic wave devices [21], piezoelectric sensors & actuators [22-23] and nanogenerators [2-3,24]. The 1D ZnO nanorods can be synthesized by various methods such as physical vapour deposition (PVD) [8], chemical vapour deposition (CVD) [25], metalorganic chemical vapour deposition (MOCVD) [26], molecular beam epitaxy (MBE) [27], pulsed laser deposition (PLD) [28], hydrothermal synthesis [3,24,29]and electrochemical deposition [30]. Among all these methods, solution growth assisted hydrothermal synthesis is most favourable due to its flexibility to carry out the synthesis process on variety of substrates (both conducting and non-conducting) at low temperatures (<100°C). Moreover, this process is ...