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In this article, synthesis of white-light-emitting, highly stable carbon dots (CDs) using a colloidal synthesis technique is reported. It has been observed that the use of a non-coordinating solvent plays a vital role in the successful fabrication of highly stable CDs. Dilution-independent emissive behavior in CDs is achieved. Excitation-energy-dependent emissive behavior is observed in CDs. However, by surface passivating the CD core by using hexadecylamine (HDA), excitation wavelength dependence of emission is successfully minimized. Surface-functionalized CDs (SFCDs) show blue to green light tunable emission with the change in synthesis conditions. HDA also plays an important role in achieving dilution-independent emission in SFCDs. Furthermore, the carbon dots synthesized are highly inert, and their emission spectra are unaffected on exposure to an open atmosphere for as long as 9 days. A new class of highly crystalline carbon dots called ``carbon onion rings'' is reported.

Thin film transistor (TFT) active matrix backplanes are used in large area electronic systems, such as displays and image sensors. With backplanes being fabricated on wearable and flexible substrates, the possibilities of operational faults in backplanes have increased. These faults could either be hard faults, such as line opens or shorts or could be softer faults, such as time dependent variations in the TFT transfer characteristics. Real time diagnosis of these faults require built-in-self-test systems. While many such systems have been demonstrated to diagnose hard faults, an easily realizable system to identify soft faults, such as variations in transistor transconductance remain an open challenge. In this paper, we discuss a system that extracts the transconductance by charging and then discharging the pixel capacitor at various gate voltages for an active matrix liquid crystal display backplane. This permits a plot of the time averaged current versus the gate voltage from which the spatial variation of transconductance can be extracted. The details of the design are discussed and a proof of concept with a $3\times 4$ amorphous silicon backplane is demonstrated.

A highly sensitive, selective, and rapid interference green synthesis based determination of potential milk adulterant melamine has been reported here. Melamine is a nitrogenous compound added to milk for mimicking proteins, consumption of which leads to kidney stones and renal failures. Melamine interacts with ascorbic acid (AA) through strong hydrogen-bonding interactions, thus resulting in an interference/interruption in the formation of silver (Ag) nanoparticles which was confirmed by UV-Vis spectroscopy and Transmission Electron Microscopy (TEM). The corresponding benchmark validations for melamine spiked milk samples were performed using High Performance Liquid Chromatography (HPLC). This interference in the formation of Ag nanoparticles resulted in color change that varies with concentration of melamine, thereby enabling in-situ rapid sensing of melamine from milk to a lower limit of 0.1 ppm with a linear correlation coefficient of 0.9908. (C) 2016 Elsevier B.V. All rights reserved.

Multi-scan waveguides have been inscribed in GeS2 glass sample with different pulse energies and translation speeds. Mechanical and structural changes on GeS2 binary glass in response to irradiation to 1047 nm femto-second laser pulses have been investigated. The optical characterization of these waveguides has been done at 1550 nm of laser wavelength and the material response to laser exposure is characterized by both nanoindentation studies and micro-Raman spectroscopy. Nanoindentation investigations show a decrease in hardness (H) and elastic modulus (E) upon laser irradiation. The change in E and H are found to be varying with the translational speed, pulse energy and hence the net-fluence at the sample. These changes are correlated with variations in the Raman response of photo-exposed glass which is interpreted in terms of structural modifications made by the laser inscriptions to the glassy network. The mechanical behavior and local structural changes on waveguide writing is found to be dependent on net-fluence and it is correlated with the preparation conditions like melt temperature and cooling rate. (C) 2017 Elsevier B.V. All rights reserved.

Separating the particles from the liquid component of sample solutions is important for several microfluidic-based sample preparations and/or sample handling techniques, such as plasma separation from whole blood, sheath-free flow focusing, particle enrichment etc. This paper presents a microfluidic in-flow decantation technique that provides the separation of particles from particle-free fluid while in-flow. The design involves the expansion of sample fluid channel in lateral and depth directions, thereby producing a particle-free layer towards the walls of the channel, followed by gradual extraction of this particle-free fluid through a series of tiny openings located towards one-end of the depth-direction. The latter part of this design is quite crucial in the functionality of this decantation technique and is based on the principle called wee-extraction. The design, theory, and simulations were presented to explain the principle-of-operation. To demonstrate the proof-of-principle, the experimental characterization was performed on beads, platelets, and blood samples at various hematocrits (2.5%&ndash, 45%). The experiments revealed clog-free separation of particle-free fluid for at least an hour of operation of the device and demonstrated purities close to 100% and yields as high as 14%. The avenues to improve the yield are discussed along with several potential applications.

We demonstrate room temperature nitrogen dioxide (NO2) sensing at parts per billion level (ppb) using a chemiresistive sensor based on strontium nanoparticles decorated reduced graphene oxide. Among the various functional materials used for NO2 sensing, it is a unique study reported for the first time using hybrid of reduced graphene oxide with a low work function alkaline earth metal. An increase of nearly 222% in sensing response is observed in the hybrid device over reduced graphene oxide alone at a concentration of 1 ppm. Moreover, the hybrid device exhibits a good sensitivity to NO2 over a wide concentration range from 500 ppb to 104 ppm. Additionally, the hybrid device is highly selective to NO2 amongst other pollutants. The integration of strontium nanoparticles onto reduced graphene oxide imparts excellent performance to the hybrid sensor due to their high adsorption energy for NO2. Further, strontium nanoparticle, being a low work function material, raises the fermi level of reduced graphene oxide and populate it with more electrons thus facilitating rapid charge transfer to electrophilic nitrogen dioxide. Hence, strontium nanoparticles attribute to an important role in fast and selective adsorption of nitrogen dioxide at room temperature with underlying graphene helping in rapid charge transfer.

In this paper, we present the fabrication and characterization of molybdenum microheaters for high-temperature gas sensing applications. The surface morphology of dc magnetron sputtered molybdenum thin films was characterized by scanning electron microscopy and atomic force microscopy. The suspended membrane microheater consumed 104 mW to reach a maximum temperature of 800 degrees C and showed an absolute thermal resistance of 7.2 degrees C/mW. Thermal distribution patterns over the active heating area were recorded using FLIR camera. It showed a temperature gradient of 1.18 % from the center of the microheater to its periphery. The thermal and mechanical stabilities of the microheater were analyzed, and its membrane failure at higher operating temperatures was prevented. The microheater membrane deformation at different temperatures was characterized using optical profilometer, and its maximum value was found to be 16.25 mu m at 800 degrees C. The microheater response to a pulse, continuous pulse train, and constant dc voltages was characterized. Its response and recovery times are in the order of 19 and 34 ms, respectively. It showed a stable temperature with a negligible resistance drift (0.96%) over a period of 600 h. The TiO2 thin film integrated molybdenum microhotplate-based MEMS gas sensor response for CO (5000 ppb) was measured at different operating temperatures (300 degrees C-700 degrees C).

Pulmonary function tests (PFTs) are noninvasive diagnostic tests that evaluate the functionality of the lungs. Spirometry is an established diagnostic tool for the evaluation and management of lung disorders. Pulmonary function testing carried out using a spirometer provides vital information about the functional status of the respiratory system. In this study, a spirometer based on a fiber Bragg grating (FBG) sensor for PFT has been proposed. The proposed fiber Bragg grating spirometer (FBGS) is a novel, noninvasive device that has the ability to convert the rate of air flow into strain variations using an FBG sensor bonded on a cantilever. The FBGS dynamically acquires in real time, the complete breath sequence comprising of inhalation phase, pause phase, and exhalation phase, in terms of the air flow rate along with the time duration of each phase. Fundamental pulmonary parameters such as forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), the FEV1/FVC ratio, and peak expiratory flow are evaluated from the data obtained from the FBGS, which will aid greatly during clinical tests. The results from the FBGS developed are compared with a standard hospital grade pneumotachograph-based spirometer for a sample size of 16 subjects to prove the efficacy of the proposed device.

Polycrystalline copper indium gallium diselenide (CIGS) thin film is a favourable candidate for solar cell applications. In the present work the effect of post-deposition annealing on the structure, surface morphology, optical and electrical properties are discussed. Initially, gallium rich CIG thin films were deposited by RF magnetron sputtering followed by an indium rich CIG layer and subjected to selenization to realize CIGS stoichiometry. X-ray diffraction (XRD) results revealed the polycrystalline nature of the films with chalcopyrite structure having preferential orientation along direction normal to the substrate. Optical properties of CIGS thin films were studied using UV-vis spectrophotometry and the band gap of CIGS was found to be around 1.15 eV. Hall Effect studies carried out on the CIGS thin films showed a linear dependence of conductivity with post deposition annealing. The elemental composition of the films was quantified using X-ray photoelectron spectroscopy (XPS) and the results are discussed. (C) 2016 Elsevier B.V. All rights reserved.

Lithium-sulfur batteries mostly suffer from the low utilization of sulfur, poor cycle life, and low rate performances. The prime factors that affect the performance are enormous volume change of the electrode, soluble intermediate product formation, poor electronic and ionic conductivity of S, and end discharge products (i.e., Li2S2 and Li2S). The attractive way to mitigate these challenges underlying in the fabrication of a sulfur nanocomposite electrode consisting of different nanoparticles with distinct properties of lithium storage capability, mechanical reinforcement, and ionic as well as electronic conductivity leading to a mechanically robust and mixed conductive (ionic and electronic conductive) sulfur electrode. Herein, we report a novel bottom-up approach to synthesize a unique freestanding, flexible cathode scaffold made of porous reduced graphene oxide, nanosized sulfur, and Mn3O4 nanoparticles, and all are three-dimensionally interconnected to each other by hybrid polyaniline/sodium alginate (PANI-SA) matrix to serve individual purposes. A capacity of 1098 mAh g(-1) is achieved against lithium after 200 cycles at a current rate of 2 A g-1 with 97.6% of initial capacity at a same current rate, suggesting the extreme stability and cycling performance of such electrode. Interestingly, with the higher current density of 5 A g(-1), the composite electrode exhibited an initial capacity of 1015 mA h g(-1) and retained 71% of the original capacity after 500 cycles. The in situ Raman study confirms the polysulfide absorption capability of Mn3O4. This work provides a new strategy to design a mechanically robust, mixed conductive nanocomposite electrode for high-performance lithium sulfur batteries and a strategy that can be used to develop flexible large power storage devices.

Current study relates to the development of an electrical power-free, handheld microfluidic nanoparticle synthesizer for synthesis of uniform sized silver nanoparticles at room temperature. The synthesizer module consists of a custom designed microreactor and employs negative pressure based pumping mechanism for the electrical power free synthesis of metal nanoparticles. In order to realize a microreactor capable of on-site synthesis of monodisperse nanoparticles, optimization studies by bulk biosynthesis at varying ratios of the precursor and the reducing agent followed by UV-VIS absorption studies were performed to determine the appropriate mixing ratio. Later, a custom designed microfluidic micromixer was used to perform volumetric flow rate optimizations at the desired ratio using syringe pumps. From the knowledge of the precursor and reducing agent ratio and the flow rates, we modified the hydraulic resistance of micro-mixer inlets by varying the channel geometry to meet the optimized specifications leading to effective synthesis. The synthesized nanoparticles were characterized by UV-VIS spectroscopy, XPS, FTIR, EDS, HRTEM and SAED. The crystal lattice planes of 111] and 220] from the SAED pattern confirms the presence of silver nanoparticles. HRTEM study elucidates that the size of the synthesized nanoparticles is between 2 and 10 nm.

The present work demonstrates the superhydrophobic and Surface Enhanced Raman Spectroscopy (SERS) active substrate performance of silver coated copper oxide (Ag@CuO) nanostructured thin films prepared by the SILAR process. Super hydrophobic substrates that combine super hydrophobic condensation effect and high enhancement ability of Ag@CuO nanoflowers are investigated for SERS studies. The possible growth mechanism for the formation of nanoflower arrays from nanospindles has been discussed. Morphology and crystallinity of the Ag@CuO thin films are confirmed using FESEM and XRD. The results obtained in the present study indicate that the as-deposited hydrophobic nanospindles structure converts to super hydrophobic nanoflower arrays on annealing at 200 degrees C. The Ag@CuO super hydrophobic nanoflowers thin film based SERS substrates show highly enhanced Raman spectra with an EF value of 2.0 x 10(7) for (Rhodamine 6G) R6G, allowing a detection limit from a 10(-10) mol L-1 solution. The present study may provide a new perception in fabricating efficient super hydrophobic substrates for SERS, suggesting that the fabricated substrates are promising candidates for trace analysis of R6G dye and are expected to be widely used as highly sensitive SERS active substrates for various toxic dyes in the future. (C) 2016 Elsevier Inc. All rights reserved.

Light absorption efficiency and doping induced charge carrier density play a vital role in self-powered optoelectronic devices. Unique vanadium-doped zinc oxide nanoflake array (VZnO NFs) is fabricated for self-powered ultraviolet (UV) photodetection. The light harvesting efficiency drastically improved from 84% in ZnO NRs to 98% in VZnO NFs. Moreover, the hydrogenation of as-synthesized VZnO (H:VZnO) NFs displayed an outstanding increase in response current as compared to pristine structures. The H:VZnO NFs device presents an extraordinary photoelastic behavior with faster photodetection speed in the order of ms under a low UV illumination signal. Excellent responsivity and external quantum efficiency with larger value of specific detectivity of H:VZnO NFs device promises an outstanding sensitivity for UV signal and self-powered high-performance visible-blind photodetector.

We discuss the potential application of high dc voltage sensing using thin-film transistors (TFTs) on flexible substrates. High voltage sensing has potential applications for power transmission instrumentation. For this, we consider a gate metal-substrate-semiconductor architecture for TFTs. In this architecture, the flexible substrate not only provides mechanical support but also plays the role of the gate dielectric of the TFT. Hence, the thickness of the substrate needs to be optimized for maximizing transconductance, minimizing mechanical stress, and minimizing gate leakage currents. We discuss this optimization, and develop n-type and p-type organic TFTs using polyvinyldene fluoride as the substrate-gate insulator. Circuits are also realized to achieve level shifting, amplification, and high drain voltage operation.

An electroactive poly(3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me-2) thin film was electropolymerized by cyclic voltammetry technique, and its electrochemical and electrochromic properties were systematically studied. The prepared PProDOT-Me-2 thin film was electrochemically reversible, and it showed a linear relation between peak current with scan rates. The electrochemical impedance spectrum also indicated the diffusion limitation of the film during charge/discharge process. The film showed a good color contrast (60 %) with a low applying potential of 1.2 V. The electrochromic window (ECW) based on PPro-DOT-Me-2 film was fabricated and studied for its electrochromic performance. The color contrast of the device was achieved as 36 % at lambda(max) of 560 nm. The switching speed of fabricated ECW for coloring and bleaching were almost 0.7 s in a range of +1.5 to -1.5 V. The fabricated device showed better cyclic current response and remarkable switching stability over 100 cycles. The novelty of the electrochromic window based on PProDOT-Me-2 is the maximum absorbance at photopic wavelength that would be highly sensitive to human eyes.

SU8-based micromechanical structures are widely used as thermal actuators in the development of compliant micromanipulation tools. This paper reports the design, nonlinear thermomechanical analysis, fabrication, and thermal actuation of SU8 actuators. The thermomechanical analysis of the actuator incorporates nonlinear temperature-dependent properties of SU8 polymer to accurately model its thermal response during actuation. The designed SU8 thermal actuators are fabricated using surface micromachining techniques and the electrical interconnects are made to them using flip-chip bonding. The issues due to thermal stress during fabrication are discussed and a novel strategy is proposed to release the thermal stress in the fabricated actuators. Subsequent characterization of the actuator using an optical profilometer reveals excellent thermal response, good repeatability, and low hysteresis. The average deflection is $\sim 8.5~\mu \text{m}$ for an actuation current of $\sim 5$ mA. The experimentally obtained deflection profile and the tip deflection at different currents are both shown to be in good agreement with the predictions of the nonlinear thermomechanical model. This underscores the need to consider nonlinearities when modeling the response of SU8 thermal actuators. [2015-0087]

Arterial pulse is an established source of information for the clinical assessment of cardiovascular health. The central aortic pressure is known to be a better predictor of cardiovascular status than the peripheral pressure. The carotid arterial pulse is considered to be the best indicator of the central aortic pressure. The present work deals with the development of a novel noninvasive probe based on fiber Bragg grating (FBG) sensor for the real-time acquisition of the pulse waveform in the carotid arterial site. The fiber Bragg grating pulse probe (FBGPP) developed is used to obtain the carotid arterial pulse waveform (CAPW) of individual subjects, in the form of beat-to-beat carotid pulse. The FBGPP developed comprises of an elastic rubber diaphragm that comes into contact with the skin below, which the carotid artery is pulsating, creating strain variations over it. Effectively, the carotid arterial pulse is tranduced into the strain variations over a rubber diaphragm, which is acquired by the FBG sensor bonded over it. The FBGPP is designed such that the positioning and the access for the device to the carotid arterial site can be carried out with ease. Furthermore, the recorded CAPW is subjected to the pulse wave analysis in order to evaluate vital cardiovascular parameters like heart rate, left ventricular ejection time, carotid augmentation index, and ejection duration index, which are indicators of the cardiac health of the subject and the performance of the heart. Also, the linearity between these cardiovascular parameters is explored for a sample size of 55.

A binder-free novel three-dimensional assembly comprising graphene, carbon nanoparticles and nickel hydroxide is presented as a supercapacitor electrode. The combined effect of three-dimensional graphene for excellent charge conduction and nickel hydroxide coating on carbon nanoparticles for high surface area was exploited to obtain excellent supercapacitance. The resulting structure presented an ultrahigh 4667 F g(-1) specific capacitance at a 2 A g(-1) discharge rate with 98.6% high charge retention for more than 1000 charge-discharge cycles. In addition, the presented assembly demonstrated very high power and energy densities.

Superhydrophobic surfaces have attracted due to their potential applications such as self-cleaning surfaces etc. Many techniques have demonstrated in fabricating the artificial superhydrophobic surfaces such as CVD, Organic coatings etc. In this paper we present simple approach to fabricate non wettable superhydrobic surface on silicon Nanowires (Si NW) surface by H-2 ion etching technique through ECR device which is very efficient in producing the high ion density plasma at low pressure and at moderate energy. Large area high density (Si NW) were fabricated by two step Metal assisted chemical etching (MACE) of silicon using silver(Ag) as the catalyst along with pre immersion method. H-2 Plasma ion etching treatment was applied on the surface of the SiNW at the constant microwave power. The morphology of Si NWs is changed with the application of plasma which was revealed by Scanning electron microscopy. Water contact angles have been systematically measured for SiNWs& H-2 plasma treated SiNWs by increasing the etching time. It was observed that in H-2 ion plasma treated SiNWs, the water contact angle changed dramatically from 22.6 degrees to 146 degrees almost near to super hydrophobic nature. And these result suggest that the hydrogen plasma condition must be carefully regulated to achieve the superhydrophobic surface on silicon which is essential for many applications like Biosensors and Microfluidic surfaces. (C) 2015Elsevier Ltd. All rights reserved.

Ferroelectricity in ZnO is an unlikely physical phenomenon. Here, we show ferroelectricity in undoped 001] ZnO nanorods due to zinc vacancies. Generation of ferroelectricity in a ZnO nanorod effectively increases its piezoelectricity and turns the ZnO nanorod into an ultrahigh-piezoelectric material. Here using piezoelectric force microscopy (PFM), it is observed that increasing the frequency of the AC excitation electric field decreases the effective d(33). Subsequently, the existence of a reversible permanent electric dipole is also found from the P-E hysteresis loop of the ZnO nanorods. Under a high resolution transmission electron microscope (HRTEM), we observe a zinc blende stacking in the wurtzite stacking of a single nanorod along the growth axis. The zinc blende nature of this defect is also supported by the X-ray diffraction (XRD) and Raman spectra. The presence of zinc vacancies in this basal stacking fault modulates p-d hybridization of the ZnO nanorod and produces a magnetic moment through the adjacent oxygen ions. This in turn induces a reversible electric dipole in the non-centrosymmetric nanostructure and is responsible for the ultrahigh-piezoelectric response in these undoped ZnO nanorods. We reveal that this defect engineered ZnO can be considered to be in the competitive class of ultrahigh-piezoelectric nanomaterials for energy harvesting and electromechanical device fabrication.

The effects of optical and magnetic fields have a pronounced influence on the electrical performance of graphene quantum dots (GQDs). Nonlinear current-voltage hysteresis during a voltage sweep is revealed due to the charge traps by adsorbates present on the quantum dot (QD) surface. Hence, a polarization dependent variation in QDs even in the presence of the surrounding medium presented an interesting variation in the electrical conductivity. Furthermore, a study of capacitance with frequency revealed that the microwave heating time (MHT) during the preparation of GQDs greatly affected the capacitance value of the colloidal QDs owing to size variation where larger QDs arising from a greater MHT showed lower capacitance and vice versa.

Thin films of different thicknesses in the range of 200-720 nm have been deposited on glass substrates at room temperature using thermal evaporation technique. The structural investigations revealed that the as-deposited films are amorphous in nature. The surface roughness of the films shows an increasing trend at higher thickness of the films. The surface roughness of the films shows an increasing trend at higher thickness of the films. Interference fringes in the transmission spectra of these films suggest that the films are fairly smooth and uniform. The optical absorption in Sb2Se3 film is described using indirect transition and the variation in band gaps is explained on the basis of defects and disorders in the chalcogenide systems. Raman spectrum confirms the increase of orderliness with film thickness. From the I-V characteristics, a memory type switching is observed whose threshold voltage increases with film thickness. (C) 2015 Elsevier B.V. All rights reserved.

Power densities required to operate active-matrix organic-light-emitting diode (AMOLED) based displays for high luminance applications, lead to temperature rise due to self heating. Temperature rise leads to significant degradation and consequent reduction in life time. In this work numerical techniques based computational fluid dynamics (CFD) is used to determine the temperature rise and its distribution for an AMOLED based display for a given power density and size. Passive cooling option in form of protruded rectangular fins is implemented to reduce the display temperature.

Titania aerogels were synthesized by sol-gel route followed by ambient pressure subcritical drying technique. The aerogels synthesized in the present work possess a maximum surface area of 252 m(2)/g. The pore size distribution is between 2 and 30 nm which confirms their mesoporosity. The oxygen plasma treatment on titania aerogel thin films improved the surface area up to 273 m(2)/g and produced additional hydrophilic groups on the surface. It is confirmed by BET surface area, XPS and thermal analysis in conjunction with dye adsorption studies. After plasma treatment the dye adsorption capacity was increased 2.5 times higher than that of untreated aerogel film. The increased surface area and the hydrophilic groups generated on the titania aerogel surface during plasma treatment are responsible for enhanced dye adsorption. The overall nanoporous morphology of titania aerogel is preserved after plasma treatment. (C) 2015 Elsevier B.V. All rights reserved.

Direct measurement of three-dimensional (3-D) forces between an atomic force microscope (AFM) probe and the sample benefits diverse applications of AFM, including force spectroscopy, nanometrology, and manipulation. This paper presents the design and evaluation of a measurement system, wherein the deflection of the AFM probe is obtained at two points to enable direct measurement of all the three components of 3-D tip-sample forces in real time. The optimal locations for measurement of deflection on the probe are derived for a conventional AFM probe. Further, a new optimal geometry is proposed for the probe that enables measurement of 3-D forces with identical sensitivity and nearly identical resolution along all three axes. Subsequently, the designed measurement system and the optimized AFM probe are both fabricated and evaluated. The evaluation demonstrates accurate measurement of tip-sample forces with minimal cross-sensitivities. Finally, the real-time measurement system is employed as part of a feedback control system to regulate the normal component of the interaction force, and to perform force-controlled scribing of a groove on the surface of polymethyl methacrylate.

Mechanical properties of thin films such as residual stress and hardness are of paramount importance from the device fabrication point of view. Intrinsic stress in sputtered films can be tensile or compressive as decided by the number density and the energy of the plasma species striking the growing film. In the presence of hydrogen we analyzed the applicability of idealized stress reversal curve for amorphous silicon thin films deposited by DC, pulsed DC (PDC) and RF sputtering. We are successfully able to correlate the microstructure with the stress reversal and hardness. We observed a stress reversal from compressive to tensile with hydrogen incorporation. It was found that unlike in idealized stress reversal curve case, though the energy of plasma species is less in DC plasma, DC deposited films exhibit more compressive stress, followed by PDC and RF deposited films. A tendency towards tensile stress from compressive stress was observed at similar to 13, 18 and 23 at%H for DC, PDC and RF deposited films respectively, which is in exact agreement with the vacancy to void transition in the films. Regardless of the sputtering power mode, the hardness of a-Si:H films is found to be maximum at C-H similar to 10 at%H. Enhancement in hardness with C-H (up to C-H similar to 10 at%H) is attributed to increase of Si-H bonds. Beyond C-H similar to 10 at%H, hardness starts falling. (C) 2015 Elsevier Ltd. All rights reserved.

Disease conditions like malaria, sickle cell anemia, diabetes mellitus, cancer, etc., are known to significantly alter the deformability of certain types of cells (red blood cells, white blood cells, circulating tumor cells, etc.). To determine the cellular deformability, techniques like micropipette aspiration, atomic force microscopy, optical tweezers, quantitative phase imaging have been developed. Many of these techniques have an advantage of determining the single cell deformability with ultrahigh precision. However, the suitability of these techniques for the realization of a deformability based diagnostic tool is questionable as they are expensive and extremely slow to operate on a huge population of cells. In this paper, we propose a technique for high-throughput (800 cells/s) determination of cellular deformability on a single cell basis. This technique involves capturing the image(s) of cells in flow that have undergone deformation under the influence of shear gradient generated by the fluid flowing through the microfluidic channels. Deformability indices of these cells can be computed by performing morphological operations on these images. We demonstrate the applicability of this technique for examining the deformability index on healthy, diabetic, and sphered red blood cells. We believe that this technique has a strong role to play in the realization of a potential tool that uses deformability as one of the important criteria in disease diagnosis.

We investigated the effect of oxygen flow rate during the reactive magnetron sputtering on the compositional, structural, optical and electrical properties of HfO2 films. We also studied the influence of annealing temperature on the structural and electrical properties of optimized HfO2 films of 25 to 30 nm thick. X-ray photoelectron study reveals that the films deposited at 15 SCCM of oxygen flow rate are stoichiometric and have an optical band gap of 5.86 eV. X-ray diffraction indicates that films without oxygen flow are amorphous, and beyond an oxygen flow rate of 5 SCCM exhibit polycrystalline monoclinic structure. At an annealing temperature of 600 degrees C, tetragonal phase was observed besides the monoclinic phase. The dielectric constant of 11 and low leakage currents of 1 x 10(-7) A/cm(2) were achieved for the stoichiometric films. As-deposited films show significant frequency dispersion due to the presence of defect states at the HfO2/Si interface, and it reduces after annealing.

The variation of normalized electrical resistivity in the system of glasses Ge15Te85-xSnx with (1

Manganese dioxide nanoparticles were synthesized by chemical reduction route at different growth temperatures of 40 degrees C, 80 degrees C, 100 degrees C and were characterized using X-ray Diffraction (XRD), Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Cyclic Voltammetry (CV) and chronoamperometry (CA) analysis. FESEM results show that on increasing growth temperature the morphology changes from clusters into mixture of rods and flakes. XPS analysis reveals the formation of MnO2. Then these particles were immobilized on Pt electrode. A platinum (Pt) electrode modified with low dimensional MnO2 was investigated as a chronoamperometric (CA) sensor for hydrogen peroxide sensing (H2O2). The sample prepared at 100 degrees C shows good electrocatalytic ability for H2O2 sensing when compared with the samples prepared at 40 degrees C and 80 degrees C. At an operating potential of 0.3 V vs. Ag/AgCl catalytic oxidation of the analyte is measured for chronoamperometric (CA) monitoring. The CA signals are linearly proportional to the concentration of H2O2. It is also found that the morphology of the nanostructure plays a vital role in the detection of H2O2. (C) 2014 Elsevier Ltd. All rights reserved.

We demonstrate a non-invasive technique, based on the modal frequency shift of a region insonified by a dual-beam ultrasound (US) transducer (region of interest, ROI), to remotely assess the temperature of the region in a tissue-mimicking object. The application is in ultrasound hyperthermia systems for controlled maintenance of tumour temperature during chemotherapy. Towards this, we have characterised the variation of the storage modulus with the temperature of two tissue-mimicking visco-elastic materials. Due to this variation in tissue storage modulus (and viscosity), we have observed a shift in the resonant modes of the ROI, vibrated remotely with a dual-beam focussed ultrasound transducer. A modal analysis of the vibrating ROI is done to identify the modes captured by the detector. A variation in this modal frequency with temperature is computed and matches reasonably well with the experimental measurements. Through this, we demonstrate that an ultrasound hyperthermia system can have a remote temperature sensor without using an additional imaging modality.

Microwave plasma driven chemical vapour deposition was used to synthesize graphene nanosheets from a mixture of acetylene and hydrogen gas molecules. In this plasma, acetylene decomposes to carbon atoms that form nanostructures in the outlet plasma stream and get deposited on the substrate. The GNS consists of a few layers of graphene aligned vertically to the substrate. Graphene layers have been confirmed by high-resolution transmission electron microscopy, and Raman spectral studies were conducted to observe the defective nature of the sample. The growth of nanosheets in a vertical direction is assumed to be due to the effect of electric field and from the difference in the deposition rate in the axial and parallel directions. These vertical graphene sheets are attractive for various applications in energy storage and sensors.

Ready to use screen printed glucose sensors are fabricated using Prussian Blue (PB) and Cobalt PhthaloCyanine (CoPC) mediated carbon paste as working electrodes. The reference and counter electrodes are screen printed using silver/silver chloride and graphitic carbon paste respectively. The stability of screen printed reference electrode (SPRE) is examined with standard calomel electrode and found to be stable for more than 60 minutes. Optimal operating voltage for PB and CoPC screen printed sensors as determined by hydrodynamic voltammetric technique are 0.3 V and -0.1 V respectively. The sensing response of fabricated sensors towards H2O2 is conducted. Amperometric sensing response of PB screen printed sensor to H2O2 has limit of detection (LOD) of 0.5 μM with sensitivity of 63.690 mAcm-2/mM. Sensing response is found to be linear for the range, 1 to 4500 μM. While the CoPC screen printed sensor has LOD 0.05 μM with sensitivity of 56.66 mA cm-2/mM to H2O2. The response is linear for the range, 0.1 to 7500 μM. Glucose oxidase is immobilized on the working electrodes by cross-linking method using Glutaraldehyde and Nafion. Electrochemical sensing responses of the fabricated sensors for glucose are studied. PB mediated glucose sensor exhibits a sensitivity of 5.60 mA cm-2/mM with LOD of 7 μM. The response is observed to be linear for the range, 10 to1000 μM with linearity co-efficient of 0.9990. Sensitivity and LOD of CoPC mediated glucose sensor are found to be 5.224 mA cm-2/mM and 70 μM respectively. The amperometeric response is linear for the range, 100 to 1500 μM with linearity co-efficient of 0.9973. Inference studies on the fabricated glucose sensors are conducted with species like uric acid and ascorbic acid. PB mediated sensors showed a completely interference-free behavior, while CoPC mediated sensors are influenced by uric acid and ascorbic acid due to higher operating voltage. The sensing response of PB mediated glucose sensors is also studied in diluted human serum samples and the results are compared with values obtained by standard spectrometric method. The correlation co-efficient is found to be 0.935 and hence the sensor has potential application in clinical diagnostics. Figure 1

A conceptually new approach is proposed to estimate the thermal diffusivity of optically transparent solids at ambient temperature based on the `position-dependent instantaneous velocity' of isothermal surfaces using a self-reference interferometer. A new analytical model is proposed using the exact solution to relate the instantaneous velocity of isothermal surfaces with the thermal diffusivity of solids. The experiment involves setting up a one-dimensional non-stationary heat flow inside the solid via step-temperature excitation to launch a spectrum of dissimilar `moving isothermal surfaces' at the origin. Moving isothermal surfaces exhibit macroscale `rectilinear translatory motion'; the instantaneous velocity of any isothermal surface at any location in the heat-affected region is unique and governed by the thermal diffusivity of the solids. The intensity pattern produced by the self-reference interferometer encodes the moving isothermal surfaces into the corresponding moving intensity points. The instantaneous velocities of the intensity points are measured. For a given thermo-optic coefficient, the corresponding values of the isothermal surfaces are predicted to estimate the thermal diffusivity of the solids using BK7 glass as an example. Another improved method is proposed in which thermal diffusivity is estimated without measuring thermo-optic coefficient and quartz glass is utilized as a specimen. The results obtained using the proposed approaches closely match with the literature value.

Investigations on the electrical switching, structural, optical and photoacoustic analysis have been undertaken on chalcogenide GeSe1.5S0.5 thin films of various thicknesses prepared by vacuum evaporation technique. The decrease of band gap energy with increase in film thickness has been explained using the `density of states model'. The structural units of the films are characterized using Raman spectroscopy and the deconvoluted Raman peaks obtained from Gaussian fit around 188 cm(-1), 204 cm(-1) and 214 cm(-1) favors Ge-chalcogen tetrahedral units forming corner and edge sharing tetrahedra. All the thin films samples have been exhibited memory-type electrical switching behavior. An enhancement in the threshold voltages of GeSe1.5S0.5 thin films have been observed with increase in film thickness. The thickness dependence of switching voltages provide an insight into the switching mechanism and it is explained by the Joule heating effect. (C) 2014 Elsevier B.V. All rights reserved.

SnS quantum dot solar cell is fabricated by Successive Ionic Layer Adsorption and Reaction (SILAR) method. SnS layer is optimized by different SILAR cycles of deposition. The particle size increased with the increase in number of SILAR cycles. Cu2S coated FTO is used as counter electrode against the conventional Platinum electrode. On comparison with a cell having a counter electrodeelectrolyte combination of Platinum-Iodine, Cu2S-polysulfide combination is found to improve both the short circuit current and fill factor of the solar cell. A maximum efficiency of 0.54% is obtained with an open circuit voltage of 311 mV and short circuit current density of 4.86 mA/cm. (C) 2014 Elsevier Ltd. All rights reserved.

In the present work, Li2-x MnO3-y (LMO) thin films have been deposited by radio frequency (RF) reactive magnetron sputtering using acid-treated Li2MnO3 powder target. Systematic investigations have been carried out to study the effect of RF power on the physicochemical properties of LMO thin films deposited on platinized silicon substrates. X-ray diffraction, electron microscopy, surface chemical analysis and electrochemical studies were carried out for the LMO films after post deposition annealing treatment at 500 A degrees C for 1 h in air ambience. Galvanostatic charge discharge studies carried out using the LMO thin film electrodes, delivered a highest discharge capacity of 139 mu Ah mu m(-1) cm(-2) in the potential window 2.0-3.5 V vs. Li/Li+ at 100 W RF power and lowest discharge capacity of 80 mu Ah mu m(-1) cm(-2) at 75 W RF power. Thereafter, the physicochemical properties of LMO films deposited using optimized RF power 100 W on stainless steel substrates has been studied in the thickness range of 70 to 300 nm as a case study. From the galvanostatic charge discharge experiments, a stable discharge capacity of 68 mu Ah mu m(-1) cm(-2) was achieved in the potential window 2.0-4.2 V vs. Li/Li+ tested up to 30 cycles. As the thickness increased, the specific discharge capacity started reducing with higher magnitude of capacity fading.

In this paper, we present the fabrication and characterization of Ti and Au coated hollow silicon microneedles for transdermal drug delivery applications. The hollow silicon microneedles are fabricated using isotropic etching followed by anisotropic etching to obtain a tapered tip. Silicon microneedle of 300 mu m in height, with 130 mu m outer diameter and 110 mu m inner diameter at the tip followed by 80 mu m inner diameter and 160 mu m outer diameter at the base have been fabricated. In order to improve the biocompatibility of microneedles, the fabricated microneedles were coated with Ti (500 nm) by sputtering technique followed by gold coating using electroplating. A breaking force of 225 N was obtained for the fabricated microneedles, which is 10 times higher than the skin resistive force. Hence, fabricated microneedles can easily be inserted inside the skin without breakage. The fluid flow through the microneedles was studied for different inlet pressures. A minimum inlet pressure of 0.66 kPa was required to achieve a flow rate of 50 mu l in 2 s with de-ionized water as a fluid medium. (C) 2014 Elsevier B.V. All rights reserved.

The variation of electrical resistivity in the system of glasses Ge17Te83-xTlx, with (1

ZnS nanostructures were grown on Si substrates in high vacuum by modified thermal evaporation technique. Morphology, chemical composition and structural properties of grown ZnS nanostructures were studied using scanning electron microscope (SEM), X-ray diffractometer and transmission electron microscope (TEM). SEM studies showed that morphology of the grown structures varies with incident flux and source temperature. TEM studies showed that grown nanostructures are single crystalline in nature without structural defects such as stacking faults and twins. No catalytic particle was included in this growth process, and hence these micro and nanostructures were assumed to grow by VS mechanism.

The contact behavior of tin mono sulfide (SnS) nanocrystalline thin films with zinc (Zn) and silver (Ag) contacts was studied. SnS films have been deposited on glass substrates by thermal evaporation technique at a growth temperature of 300 degrees C. The as-grown SnS films composed of vertically aligned nanocrystallites with a preferential orientation along the < 010 > direction. SnS films exhibited excellent chemical stoichiometry and direct optical band gap of 1.96 eV. These films also exhibited excellent Ohmic characteristics and low electrical resistivity with Zn contacts. The observed electrical resistivity of SnS films with Zn contacts is 22 times lower than that of the resistivity with Ag contacts. The interfacing analysis reveals the formation of conductive Zn-S layer between SnS and Zn as interfacial layer. (C) 2014 Elsevier B. V. All rights reserved.

We incorporated tin oxide nanostructures into the graphene nanosheet matrix and observed that the phase of tin oxide varies with the morphology. The highest discharge capacity and coulumbic efficiency were obtained for SnO phase of nanoplates morphology. Platelet morphology of tin oxide shows more reversible capacity than the nanoparticle (SnO2 phase) tin oxide. The first discharge capacity obtained for SnO@GNS is 1393 and 950 mAh/g for SnO2@GNS electrode at a current density of 23 mu A/cm(2). A stable capacity of about 1022 and 715 mAh/g was achieved at a current rate of 23 mu A/cm(2) after 40 cycles for SnO@GNS and SnO2@GNS anodes, respectively. (C) 2014 Elsevier Ltd. All rights reserved.

Micro-Raman studies are conducted on as-quenched and annealed Ge15Te80 -_xIn5Agx glasses to probe the structural network and its evolution with composition. These studies reveal the presence of tetrahedral GeTe4 structural units in as-quenched samples. Specific signatures of the intermediate phase (IP) are observed in the composition dependence of Raman frequencies and corresponding intensities of different modes in the composition range, 8

Mesoporous quaternary bioactive glasses and glass-ceramic with alkali-alkaline-earth oxide were successfully synthesized by using non-ionic block copolymer P123 and evaporation induced self assembly (EISA) process followed by acid treatment assisted sal-gel method. As prepared samples has been characterized for the structural, morphological and textural properties with the various analytical techniques. Glass dissolution/ion release rate in simulated body fluid (SBF) was monitored by inductively coupled plasma (ICP) emission spectroscopy, whereas the formation of apatite phase and its crystallization at the glass and glass-ceramic surface was examined by structural, textural and microscopic probes. The influence of alkaline-earth oxide content on the glass structure followed by textural property has become more evident. The pristine glass samples exhibit a wormhole-like mesoporous structure, whereas the glass-ceramic composition is found to be in three different phases, namely crystalline hydroxyapatite, wollastonite and a residual glassy phase as observed in Cerabone (R) A/W. The existence of calcium orthophosphate phase is closely associated with the pore walls comprising nanometric-sized ``inclusions''. The observed high surface area in conjunction with the structural features provides the possible explanation for experimentally observed enhanced bioactivity through the easy access of ions to the fluid. On the other hand, presence of multiple phases in glass-ceramic sample inhibits or delays the kinetics of apatite formation. (C) 2013 Elsevier Inc. All rights reserved.

In this study, we report the gas sensing behavior of BiNbO4 nanopowder prepared by a low temperature simple solution-based method. Before the sensing behaviour study, the as-synthesized nanopowder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-diffuse reflectance spectroscopy, impedance analysis, and surface area measurement. The NH3 sensing behavior of BiNbO4 was then studied by temperature modulation (50-350 degrees C) as well as concentration modulation (20-140 ppm). At the optimum operating temperature of 325 degrees C, the sensitivity was measured to be 90%. The cross-sensitivity of as-synthesized BiNbO4 sensor was also investigated by assessing the sensing behavior toward other gases such as hydrogen sulphide (H2S), ethanol (C2H5OH), and liquid petroleum gas (LPG). Finally, selectivity of the sensing material toward NH3 was characterized by observing the sensor response with gas concentrations in the range 20-140 ppm. The response and recovery time for NH3 sensing at 120 ppm were about 16 s and about 17 s, respectively.

Practical phantoms are essential to assess the electrical impedance tomography (EIT) systems for their validation, calibration and comparison purposes. Metal surface electrodes are generally used in practical phantoms which reduce the SNR of the boundary data due to their design and development errors. Novel flexible and biocompatible gold electrode arrays of high geometric precision are proposed to improve the boundary data quality in EIT. The flexible gold electrode arrays are developed on flexible FR4 sheets using thin film technology and practical gold electrode phantoms are developed with different configurations. Injecting a constant current to the phantom boundary the surface potentials are measured by a LabVIEW based data acquisition system and the resistivity images are reconstructed in EIDORS. Boundary data profile and the resistivity images obtained from the gold electrode phantoms are compared with identical phantoms developed with stainless steel electrodes. Surface profilometry, microscopy and the impedance spectroscopy show that the gold electrode arrays are smooth, geometrically precised and less resistive. Results show that the boundary data accuracy and image quality are improved with gold electrode arrays. Results show that the diametric resistivity plot (DRP), contrast to noise ratio (CNR), percentage of contrast recovery (PCR) and coefficient of contrast (COC) of reconstructed images are improved in gold electrode phantoms. (C) 2013 Elsevier Ltd. All rights reserved.

Silver Indium Di-sulfide (AgInS2) thin films are deposited using ultrasonic spray pyrolysis technique and the effect of substrate temperature (T-s) on film growth is studied by varying the temperature from 250 to 400 degrees C. From the structural analysis, orthorhombic AgInS2 phase is identified with preferential orientation along (002) plane. Further analysis with Raman revealed the coexistence of Cu-Au ordered and chalcopyrite structures in the films. Stoichiometric films are obtained at T-s of 300 degrees C. Above 300 degrees C, the film conductivity changed from p to n-type and the grain size decreased. The band gap of AgInS2 films varied from 1.55 to 1.89 eV and absorption coefficient is found to be >10(4) cm(-1). The films have sheet resistance in the range of 0.05 to 1300 Omega/square Both p and n type films are prepared through this technique without any external doping. (C) 2013 Elsevier B.V. All rights reserved.

This paper describes an ab initio design and development of a novel Fiber Bragg Grating (FBG) sensor based strain sensing plate for the measurement of plantar strain distribution in human foot. The primary aim of this work is to study the feasibility of usage of FBG sensors in the measurement of plantar strain in the foot; in particular, to spatially resolve the strain distribution in the foot at different regions such as fore-foot, mid-foot and hind-foot. This study also provides a method to quantify and compare relative postural stability of different subjects under test; in addition, traditional accelerometers have been used to record the movements of center of gravity (second lumbar vertebra) of the subject and the results obtained have been compared against the outcome of the postural stability studies undertaken using the developed FBG plantar strain sensing plate. (C) 2013 Elsevier Ltd. All rights reserved.

Chalcopyrite Cu(In,Al)Se-2 (CIAS) thin films are grown on stainless steel substrate through one-step electrodeposition at room temperature. Indium is partially replaced with aluminum to increase the band gap of CuInSe2 without creating significant change in the original structure. The deposition potential is optimized at -0.8 V (vs. SCE) and annealing of the films is performed in vacuum to remove binary phases present in the as-deposited films. In/Al ratio is varied from 1/9 to 8/2, to find the suitability for solar cell fabrication. For In/Al ratio of less than 8/2, CuAlSe2 phase is formed in the film in addition to the CIAS phase. Depth profile X-ray photoelectron spectroscopy analysis of the CIAS sample prepared with In/Al ratio of 8/2 in the precursor solution confirmed the existence of single phase CIAS throughout the film. This film showed p-type conductivity while the rest of the samples with In/Al ratio less than 8/2 showed n-type conductivity. The band gap of the film varied from 1.06 to 1.45 eV, with variation in deposition potential. Structural, optical, morphological, compositional and electrical characterizations are carried out to establish the suitability of this film for solar cell fabrication. (C) 2013 Elsevier B.V. All rights reserved.

Amorphous Ge15Te85-xSix thin film switching devices (1