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A novel, highly sensitive and low cost Long Range Surface Plasmon Resonance (LRSPR) biosensor for detecting uric acid, as a model analyte, has been developed in this work. Silicon dioxide (SiO

Light elements like carbon may enter unintentionally into a material during material processing owing to their ubiquitous nature, and may significantly influence its observed electronic and magnetic properties. In the present work, the energetics and kinetics of carbon impurity related defects in BiFeO

An efficient matrix comprising a hybrid nanocomposite of zinc oxide (ZnO) and multiwalled carbon nanotubes (MWCNTs) has been synthesised on indium tin oxide coated glass slides (ITO/Glass) using a chemical route deposition technique for the realization of an efficient urea biosensor. Urease (Urs) was used as the specific enzyme for urea detection and was physically immobilized over the surface of the hybrid nanocomposite matrix based (ZnO–MWCNT/ITO) electrode. The fabricated Urs/ZnO–MWCNT/ITO bioelectrode was characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetric (CV) techniques. The nanocomposite based bioelectrode i.e. Urs/ZnO–MWCNT/ITO exhibits enhanced biosensing response characteristics as compared to that of the bare ZnO based (Urs/ZnO/ITO) bioelectrode. The prepared bioelectrode (Urs/ZnO–MWCNT/ITO) exhibits a very high sensitivity of about 43.02 μA mM−1 cm−2 and a long shelf-life of more than 4 months (>16 weeks). The low Michaelis–Menten parameter (Km) value, only 0.85 mM, indicates high affinity of the immobilized urease on the surface of hybrid nanocomposite matrix towards its analyte (urea). The obtained results in the present study are encouraging and will pave the way towards the realization of an efficient urea biosensor.

Numerous important advancements toward developing a novel era of supercapacitors are being published in the past few years. There has been advancement in comprehending theory, synthesizing material, and designing devices concerning supercapacitors. The development of self-charging supercapacitors is rapidly gaining attention due to converting and storing energy in an integrated system. To address the energy shortage, studies have discovered novel techniques for integrating two devices (energy harvester and storage) to create a self-charged device (wearable/versatile electronics) suitable for various applications covering micro to macroscopic level (electric vehicles and fitness monitoring systems). We summarize state-of-the-art progress toward self-charging piezoelectric supercapacitors’ mechanism, materials, and various challenges. In this review, the central theme is a fundamental understanding of energy storage and energy harvesting mechanisms. Secondly, some emerging piezoelectric materials such as polyvinylidene difluoride (PVDF), siloxene, barium titanate (BaTiO3), potassium-sodium niobate (K0.5Na0.5NbO3), oxides, and bio-piezoelectric materials are discussed. The various challenges and future developments regarding further research in this thriving field have also been highlighted.

In the present work, RF magnetron sputtering technique has been exploited with varied deposition parameters (optimized parameters: sputtering pressure = 20 mT, 100% O2 gas ambient, without any substrate heating) to develop nanostructured NiO thin film matrix with increased surface roughness (5.09 nm) and good charge transfer properties for efficient detection of cortisol. Electrochemical and electrical studies have been performed to determine charge communication characteristics and conductivity of the prepared NiO thin film that could yield enhanced biosensing response properties. The biosensing response has been studied on the optimized parameters using cortisol as a test analyte and a relatively high sensing response of 14 μA (ug/mL)−1 has been obtained for the optimized NiO matrix-based electrodes (Cortisol-Ab/NiO/ITO).

Modifications in the structural, optical properties and surface morphology of RF sputtered WO3 thin films after irradiation with 100 MeV Ni7+ ions have been reported in the present article. The WO3 thin films were deposited at different sputtering pressures (10–50 mTorr). Despite the grain growth due to irradiation, no structural phase transformation has been observed for the WO3 thin films deposited up to 30 mTorr growth pressure. However, complete amorphization post irradiation was detected for the orthorhombic WO3 thin film grown at 50 mTorr sputtering pressure. AFM images indicated that the pristine WO3 thin film consists of uniform grains having smooth surface morphology. Upon irradiation, grain size increased consistently along with increase in surface roughness (Rq) at all sputtering pressures. The root mean square roughness (Rq) estimated from AFM analysis increased from 1.76 nm in pristine film to 9.89 nm in response to irradiation at a fluence of 1 × 1012 ions cm−2. A systematic decrease in optical band gap has been observed with irradiation, which can be correlated with Ni7+ ion induced mid-gap and near band edge defect states. Surface Plasmon Resonance (SPR) technique has been recognized as an appropriate tool to study the optical properties of pristine and irradiated WO3 thin films. SPR reflectance curves were recorded in angular interrogation mode at 633 nm excitation wavelength for pristine and Ni7+ ions irradiated WO3 films deposited at varying deposition pressure.

Present work reports the photovoltaic (PV) effect in different metal top electrodes decorated multiferroic BFO thin films. Polycrystalline BFO thin film has been deposited on Platinum (Pt) coated silicon substrates successfully through Pulsed laser deposition (PLD) technique. Different Metal top electrodes (Au, Cu, Ag, and Al) of 200 μm diameter were deposited on BFO thin films using thermal evaporation technique and their influence on ferroelectric and photovoltaic properties including Jsc -short circuit current, Voc -open circuit voltage and Ion/Ioff has been investigated. Variation in photovoltaic properties with different metal contacts has been related to the leakage current and ferroelectric polarization. Au/BFO/Pt structure exhibited improved ferroelectric properties with enhanced saturation polarization of Ps = 33.53 μC/Cm2 along with remnant polarization of Pr = 19.34 μC/Cm2 as compared to other structures. The open circuit voltage and short circuit photocurrent density were found to be −1.09 V and 11.73 mA/cm2 respectively. The elevated ferroelectric photovoltaic response obtained in current work may be accredited to the existing substantial depolarization field as a result of superior remnant polarization.

Surface Plasmon Resonance (SPR) technique has been used in the present work to study the optical properties of pulsed laser deposited single phase BiFeO3, Mn doped BiFeO3 (BFMO) and Ce doped BiFeO3 (BCFO) thin films. Refractive index dispersion studies with varying incident wavelengths has also been studied. Magnetic field dependence on the optical properties of BFMO thin films have also been determined using SPR. A very high sensitivity of 147°/Tesla was found for the prism/Au/BFMO structure exhibiting maximum change in optical properties with magnetic field indicating the potential use of BFMO thin films for the realization of efficient optical sensor.

In this paper, the linear optical response of Cr doped BiFeO3 (BFCO) using first principles calculations based on the density functional theory (DFT) is reported. The electronic and magnetic properties of BFCO are studied. Cr doping is found to result in an increase in magnetization in BFO. To corroborate the theoretical understanding in BFCO, Cr doped BFO thin film is also deposited via a multistep spin coating technique. The structural and optical characterization of the thin film are performed and the obtained results are compared with the theory.

In the present work a comparative study of electrical, dielectric and EMI shielding behaviour of copper metal-PVDF and copper ferrite- PVDF composites has been carried out. The obtained results sug...

In spite of the unique properties of graphene and considerable efforts by various researchers in last two decades to functionalize it for tailored applications, its limitations have spurred much in...

Zinc Sulphide (ZnS) has emerged as an important material in different areas like optoelectronic devices, light emitting diodes (LEDs) and photovoltaic devices, etc. Nanomaterial based ZnS have been...

We report the synthesis and optical properties of pure ZnS and Ag doped ZnS nanostructures. ZnS(Ag) was synthesized by using the hydrothermal technique and later annealed at different temperatures under vacuum conditions. It was observed that the photoluminescence (PL) emission from the ZnS(Ag) nanostructures can be easily tuned from the blue (445 nm) to green (530 nm) region of visible light by varying the annealing temperature. This tunability has been attributed to the introduction of excess sulfur vacancy states, which is evident from the PL excitation spectra. This observed change in the PL emission wavelength can be highly beneficial in the imaging screens where ZnS is regularly used and can be easily interfaced with the silicon photodiodes showing maximum sensitivity at 550 nm.

We investigate the charge carrier dynamics of inverted organic solar cells (OSCs) based on PffBT4T-2OD: PCBM and PTB7: PCBM – the two leading systems among the OSCs based on polymer-fullerene bulk-heterojunction – to elucidate the origin of their performance difference. Transient absorption spectroscopy (TAS) and photo-electrochemical impedance spectroscopy (photo-EIS) were employed to unravel the photo-physics that govern the cell operation of these two highly efficient bulk heterojunction OSCs. While photo-EIS indicates that the two systems under study exhibit similar behavior in terms of recombination, TAS results reveal that PffBT4T-2OD: PCBM systems not only have higher charge generation rate but also more efficient charge transfer than PTB7: PCBM systems, leading to the power conversion efficiency of PffBT4T-2OD: PCBM-based OSCs (9.16%) that is higher than that of PTB7: PCBM-based OSCs (6.44%).

The dynamic modulation of effective electro-optic (EO) coefficient in pulsed laser deposited SBN thin film was investigated using Senarmont Compensation method. Prism coupling technique was used to realize a waveguide to guide the light in SBN thin film. The dynamic variation of effective electro-optic coefficient over a wide frequency range (10 Hz–20 MHz) was investigated with the maximum value of 198 pm/V. This wide frequency bandwidth obtained in the present article opens up avenues to design an EO modulator using ferroelectric SBN thin film. A lower value of half wave voltage (38 V) along with high figure of merit ( 0.9 × 10 6 V 2 ) were obtained for the fabricated SBN60 thin film based EO modulator.

Modulation of light intensity utilizing Waveguide Coupled Surface Plasmon Resonance (WCSPR) technique at low driving voltage has been demonstrated in the present work. The high value of electro optic coefficient of Strontium Barium Niobate S r 0.6 B a 0.4 N b 2 O 6 ( S B N 60 ) makes it a promising material for the SPR based electro optic modulators. Prism coupling technique has been utilized for the excitation of surface plasmons in Strontium Barium Niobate (SBN) thin film in Otto configuration. Modulation of about 36% is observed due to a significant change in the refractive index of SBN60 thin film on application of electric field of 200 kV/cm. The transient response of change in reflectivity of the WCSPR system with electric field indicates the dynamic change of polarization state of SBN thin film.

Surface acoustic wave devices have widespread applications in various fields including in communication and wireless sensing devices. However some shortcomings like lower sensitivity and the corrosion of IDT’s limit their application as sensing devices. Lamb wave SAW devices have proved to be promising for sensing applications. In the present work effort has been made to find out the optimum etching temperature in order to get the sufficiently fast etch rate and smooth surface for the fabrication of SiO2/Si membrane for Lamb wave acoustic (LWA) devices. Piezoelectric ZnO thin film deposited using rf sputtering technique has been integrated with the SiO2/Si membrane. The bulk etching of Silicon has been carried out from back side of each LWA device using wet etching. The devices are packaged and frequency response is studied using a network analyzer. The antisymmetric and symmetric modes of the Lamb wave devices have been identified.

In this work, silver (Ag) nanoparticles were synthesized by simple, eco-friendly chemical reaction using aqueous extract of Rosa brunonii Lindl as a reducing agent. The characterizations using scanning electron microscopy, X-ray diffraction (XRD), energy dispersive spectrometry, UV–Vis spectrum and photo luminance spectroscopy confirmed the successful synthesis of Ag nanoparticles. The suitable antioxidant properties of as-synthesized silver nanoparticles using three assays; DPPH, FRAP and ferrous chelation potential, were confirmed. Various in vitro biological parameters of biosynthesized nanoparticles suggested an excellent antimicrobial activity against different (five bacterial and four fungal) microbial strains viz. Escherichia coli, Kleibsella pnemoniae, Campylobacter jejunii, Bacillus cereus, Alcaligenes denitrificans, Bipolaris specifera, Fusarium oxysporum, Aspergillus niger and Curvularia lunata. The as-synthesized silver nanoparticles were found most susceptible to C. jejunii (bacteria) at 47.11 µg/mL and A. niger (fungal) at 70.9 µg/mL. Further, photocatalytic property of silver nanoparticles showed a gradual increase of degradation (%) of Congo red dye under direct sunlight with respect to time for 3 h in the interval of 1 h each. The results confirmed that green synthesized silver nanoparticles are highly efficient for the photocatalytic degradation of the Congo red dye.

In the present work, the electronic and magnetic properties of Li doped BiFeO3 (BFO:Li) are calculated using density functional theory (DFT). The exchange and correlation part of the energy functio...

Present work reports on the synthesis of 2-dimensional (2D) CuO nanostructures with enhanced NO2 gas sensing properties by a facile solvothermal method. 2D CuO nanostructures were investigated usin...

In the present work efforts have been made to develop microheater integrated gas sensors with low power consumption. The design and simulation of a single-cell microheater is carried out using ANSY...

Pr3+ and Ti4+ doped BiFeO3; Bi1-xPrxFe0.80Ti0.20O3 (x = 0.05, 0.10 and 0.15) ceramics were prepared by two stage solid state sintering method. The X-ray diffraction shows large structural distortio...

In the present work, an efficient NO2 gas sensor has been realised using single phase Barium titanate, BaTiO3, (BTO) thin film, grown by chemical solution deposition technique (CSD). The gas sensin...

This paper reports the facile hydrothermal approach to synthesize porous CuO nanosheets. Their crystalline phase, metallic vibrations, topography, morphology, pore size distribution and magnetic behavior has been studied in detail. Magnetic properties of nanosheets were studied at 300 K using vibrating sample magnetometer which indicates the superparamagnetic behavior with saturation magnetization of 2.46 emu g−1 for as prepared 2D nanostructures. The electrochemical spectroscopy of these sheets reveals that as prepared sheets have a specific capacitance of 1057 F g−1 at a current density of 2 A g−1 which is retained up to 93% even after 4000 cycles. Furthermore, photocatalytic activity along with electrochemical properties of the as-obtained nanostructures were studied for various organic dyes. The high value of saturation magnetization, high specific capacitance and better dye degradation properties of the developed CuO nanosheets make the developed materials good for application in energy storage devices, astonishing electrode material and photocatalyst for degradation of organic dyes in visible light.

ZnO and Ni doped ZnO (NiZnO) thin films were fabricated on c-plane sapphire substrate using Pulsed Laser Deposition (PLD) Technique. The surface states of the deposited thin films were analyzed using X-Ray Photoelectron spectroscopy (XPS) technique. The Zn LMM Auger transitions during XPS were examined in detail to identify the doping induced structural transformations in ZnO films. Hall effect and UV-Visible spectroscopic measurements were carried out on the prepared samples to estimate the electronic and optical properties. The obtained results favor the utilization of NiZnO as active well layer and ZnO as barrier layer in NiZnO/ZnO based Quantum Well structure fabrication.

In the current work, polycrystalline BaTiO3 thin films have been synthesized on Pt/Ti/SiO2/Si substrates using the low temperature Sol gel hydrothermal method and different metal nanocluste...

Recent advances towards Electro-optic (EO) modulators make use of the Pockel’s effect in non-centrosymmetric crystals which allows the efficient modulation of light beam. The large value of electro...

Cubic Cu2−x SnxO (0 ≤ x ≤ 0.4) nanostructures have been developed with the solvothermal method. X-ray diffraction data analysis confirms the formation of a pristine Cu2O phase below $x = 0.3$ Sn2+ substitution, and SnO-related phases appear in 0.3 substitute sample indicating phase segregation starts at $x \ge 0.3$ . The magnetization versus applied field (M − H) curves have been determined using a vibrating sample magnetometer at 300 K which reveals that ferromagnetic behavior of synthesized nanomaterials is reliant on the substituent concentration and enhanced gradually with its addition in the material. Photoluminescence spectra show that ferromagnetism originates from the induced magnetic moment in defects created as cation vacancies in the host material. Beside these, the dielectric measurements were performed at various frequencies (20 Hz–1 MHz) and in the temperature range of 100 to 350 K.

A new approach to substantially improve UV/Visible photo sensitivity of nanocrystalline CdS (nc-CdS) thin films is investigated. nc-CdS thin films grown on Si wafer by pulsed laser deposition followed by irradiation treatment were used to fabricate photo-sensors. Swift heavy ion irradiation (SHII) of the nc-CdS thin films was carried out using 70 MeV 58Ni6+ ions. The influence of irradiation fluence on the transport behaviour of nc-CdS is investigated by device performance under the illuminating light of wavelengths 355 nm, 405 nm and 470 nm. Indeed, the sensors presented here are easy to fabricate without requirement of rigorous synthesis procedure. Moreover, they illustrate characteristics similar to those of photo-sensors designed with complex structures and tedious procedures. The improvement in conductivity under the exposure of SHII is a consequence of enrichment in carrier concentration as reveals from current–voltage (I–V) measurements. The sensor exhibits improvements in the response time, responsivity, photosensitivity, quantum efficiency, and specific detectivity as a function of both the ion fluence and illuminating light wavelength. These sensors show superior value of all device parameters under the illumination wavelength 470 nm of visible light. The utmost values achieved for responsivity, sensitivity, external quantum efficiency, and specific detectivity are ∼ 82 A/W, 1.02 × 103 %, 19.5 × 103 %, and 5.05 × 1011 cm Hz1/2W−1 respectively under same illumination at 5 V for 1 × 1013 ions/cm2 irradiated photosensor. Under the same illumination, bias voltage and irradiation fluence the minimum value achieved for rise time and fall time is 183 ms and 61 ms respectively. A possible mechanism involved in both the SHII and illumination wavelength induced moderation of conductivity and consequently photosensitivity is explained on the basis of variation in the defect densities.

Long-range surface plasmon resonance (LRSPR)-based sensors exhibit high sensitivity as compared to the conventional SPR sensors due to low losses. A high refractive index prism and low refractive index dielectrics are required to excite long-range surface plasmon (LRSP) mode. In this work, a symmetrical structure consisting of metal (Au) layer sandwiched between the two similar refractive index dielectrics has been utilized to excite LRSPR modes. Two dielectrics, i.e., LiF and MgF2 thin films have been chosen for glucose sensing. Theoretical simulations for optimizing the thickness of two dielectrics have been carried out. Highly sensitive refractive index sensors based on LRSPR have been developed using the two dielectric thin films and their sensitivities have been compared.

We report the fabrication of a GaN/sapphire ultraviolet (UV) photodetector (PD) with asymmetric (Pt-Ag) and symmetric (Pt-Pt) metal–semiconductor–metal (MSM) structure. The fabricated devices display Schottky behavior. Time-dependent photoresponse analysis reveals a significant enhancement in photocurrent leading to a photoresponsivity of 37 mA/W and 267 mA/W under 13 mW optical power at 5 V bias for Pt-Pt and Pt-Ag devices, respectively. Further, power-dependent measurements reveal a peak responsivity of 633 mA/W at 4mW optical power and 5 V bias for the Pt-Ag asymmetric MSM photodetector. The significant enhancement in responsivity for asymmetric MSM UV PD is ascribed to the built-in potential gradient in the GaN semiconductor, which drives a large number of charge carriers for enhanced charge collection. Further, the noise equivalent power was lowest for the Pt-Ag MSM structure, which was calculated to be 4.6 × 10−14 WHz−1/2. This high performance asymmetric MSM GaN UV PD can be integrated into efficient UV PD-based applications.

The present report aims at analyzing the quantum well (QW) structures using the highly sensitive surface plasmon resonance (SPR) technique in Otto configuration. The optical properties of ZnO and Ni doped ZnO (NiZnO) based QW structures grown using Pulsed laser deposition technique are investigated. An optimal value of QW width (8 nm) is deduced from the SPR study for maximum charge carrier confinement which is in coherence with the photoluminescence (PL) studies conducted on the same QW structures. The metal-dielectric interfaces were modelled primarily for the design of QW structures to be analysed experimentally. The mechanism behind the coupling of QWs with SP excitation has been proposed theoretically and experimentally to substantiate the results of PL and SPR studies. The variation in the SPR curves observed as a function of the QW width can be attributed to the interaction of evanescent SP field originating at the Au/QW interface and electroabsorptive behaviour of QWs towards the SP field. Keywords: Surface plasmon resonance, Quantum wells, Otto configuration, Pulsed laser deposition, Zinc oxide

Organic semiconductors (OSCs) are nowadays called upon as promising candidates for next generation electronics devices. Due to disorder structure of these materials, a high density of traps are present in their energy band gap which affect the performance of these devices. In the present manuscript, we have investigated the role of traps on charge transport in PCDTBT thin film by measuring the temperature dependent J(V) characteristics in hole only device configuration. The obtained results were analyzed by space charge limited (SCL) conduction model. It has been found that the room temperature J(V) characteristics follow Mott-Gurney square law for trap-free SCL conduction. But below 278 K, the current increases according to trap-filling SCL law with traps distributed exponentially in the band gap of semiconductor. Furthermore, after reaching a crossover voltage of VC ∽ 12 V, all the traps filled by injected carriers and the trap-filling SCL current switch to trap-free SCL current. The hole mobility of trap-free SCL current is about one order higher as compared trap-filling SCL current and remains constant with temperature.

Surface acoustic wave (SAW) devices provide a convenient platform for the realization of sensors in the present decade. 99.4 MHz SAW resonator has been fabricated over the ST cut quartz. Subsequently PZT thin film has been deposited by pulsed laser deposition technique as a sensing layer over the fabricated SAW resonator. Shift in resonance frequency was measured precisely for varying concentration of NO2 gas. The calibration curve was found to be linear having a sensitivity of 9.6 Hz/ppm. The fabricated sensor is advantageous for its room temperature, handheld and wireless sensing.

In the present work, Nanostructured ZnO sensing layers having preferred orientation along (002) plane have been grown by rf sputtering technique in glancing angle deposition (GLAD) configuration. ZnO nanostructures grown at a GLAD angle of 70° exhibit sensing response of about 5.75 × 102 at a relatively lower operating temperature of 150 °C towards 500 ppm of CO gas. Afterwards the optimized ZnO sensing element has been decorated with the Pd catalyst and an enhanced CO gas sensing response of 1.022 × 103 has been obtained with quick response time and recovery time of 17 s and 23 s respectively. The fabricated Pd/ZnO sensing element is found to be highly selective towards detection of target CO gas. The possible sensing mechanism has been explained in detail.

In the present work, zinc oxide (ZnO) thin film based Love wave acoustic device has been exploited for realization of a biosensor. These Love wave devices have been fabricated on 36°YX lithium tantalate with ZnO thin film deposited using rf sputtering technique as the guiding layer. Polydimethylsiloxane (PDMS) microchannels have been prepared and integrated on the propagation path on the fabricated device. Detection of uric acid has been demonstrated using the developed biosensing device by measuring the shift in center frequency on interaction with uric acid. The developed uric acid sensor paves way towards the realization of handheld biosensor for future wireless sensing technology.

A novel-gated structure of aluminum (Al)—perovskite (CH3NH3PbI3)—indium tin oxide (ITO), with Al as source and ITO as drain terminals, has been reported. Ambipolar nature of CH3NH3PbI3 has been explored for the device channel. Two Schottky junctions are present at source–channel and channel–drain junctions with barriers of 0.4 and 0.6 eV, respectively. Both, n- and p-type FET-like characteristics have been observed, when the device was biased, accordingly. The triangular tunneling has been observed in the output and transfer characteristics. The device shows a higher current on-off ratio ( ${I}_{ \mathrm{\scriptscriptstyle ON}}/_{ \mathrm{\scriptscriptstyle OFF}})$ of 106 with a steeper and improved sub-threshold swing (SS) of 20 ± 2 mV/decade for P tunnel field-effect transistor (TFET). However, for N TFET, ${I}_{ \mathrm{\scriptscriptstyle ON}}/_{ \mathrm{\scriptscriptstyle OFF}}$ of 104 with SS of 30 ± 2 mV/decade has been obtained.

Copper (Cu) doped p-CdS nanoparticles have been synthesized via sol-gel method. The as-synthesized nanoparticles were successfully characterized and implemented for fabrication of Glass/ITO/n-ZnO/p-CdS/Al thin film photodiode. The fabricated device is tested for small (−1 V to +1 V) bias voltage. Results verified that the junction leakage current within the dark is very small. During reverse bias condition, the maximum amount of photocurrent is obtained under illumination of 100 μW/cm2. Electrical characterizations confirmed that the external quantum efficiency (EQE), gain and responsivity of n-ZnO/p-CdS photodiode show improved photo response than conventional p-type materials for such a small bias voltage. It is therefore revealed that the Cu-doped CdS nanoparticles is an efficient p-type material for fabrication of thin film photo-devices.

Microfluidic devices offer a number of merits including reduced sample volume, fast turnaround time and highly sensitive real time measurements for lab-on-a-chip technology. Thus, we report the development of a microfluidic electrochemical biosensor for cholesterol monitoring. PDMS microchannels of dimensions 300 μm(w) x 40 μm(h) x 1 cm(l) have been fabricated using SU8 photolithography and replica molding technique. For the biosensing chip, platinum electrodes were fabricated by conventional photolithography process. The working electrode was modified by nickel oxide (NiO) thin film deposited using sputtering technique while bare platinum thin film served as the counter electrode. The microchannels were reversibly sealed with the chip by conformal contact. Cholesterol oxidase enzyme, immobilized over the NiO thin film, was employed as the specific bioreceptor for cholesterol. Highly sensitive detection of cholesterol in a wide range of concentration (0.12–10.23 mM) with a low detection limit of 0.10 mM was achieved using the fabricated microfluidic amperometric biosensor, thus demonstrating its ability for point-of-care diagnostics.

Here we investigate the effect of swift heavy ion irradiation (SHII) on various properties of chemical bath deposited nanocrystalline CdS (nCdS) thin films. For this purpose, nCdS films are exposed to the varying ion fluences (1 × 1011–1 × 1014 ion/cm2) of 80 MeV O6+ ions. Glancing angle X-ray diffraction (GAXRD) and micro-Raman studies confirm almost negligible structural transformation in CdS after ion irradiation even at highest fluence i.e. 1 × 1014 ion/cm2. GAXRD, micro-Raman spectroscopy, field emission scanning electron microscopy and UV–Visible absorption spectroscopy studies suggest that the structure, shape and size of the particles as well as band gap of the nCdS films remain unaltered upon irradiation. The quality of the films and their radiation hardness is investigated by optical as well as electrical properties using photoluminescence spectroscopy and Hall measurements respectively. The films are found to be radiation resistant for 80 MeV O6+ ion irradiation as compared to other heavy radiations. The stability of various properties of nCdS films under the impact of SHII may be due to lesser or comparable value of electronic energy loss (Se) to the threshold value of Se. Radiation hardness of nCdS thin films is a good sign for fabrication of high performance, radiation stable and long lasting solar cell for extraterrestrial applications.

Pure BiFeO3 (BFO) and Al doped BFO samples were synthesized via citrate precursor method and sintered at 500 °C for two hours. Effect of Al doping on the structural, optical, electrical, dielectric and magnetic properties were investigated. X-ray diffraction (XRD) confirmed the distorted rhombohedral structure without any merging of peaks which indicates no structural transformation. Average crystallite size was found to be in the range 28–39 nm. Field emission scanning electron microscopy (FESEM) images illustrated the dense, agglomerated, spherically shaped with reduced grain size nanoparticles. Increased value of dielectric constant with low dielectric tangent loss was observed for the Al doped BFO samples. The value of dielectric constant was found to be 51 at 100 kHz for x = 0.1 sample. Temperature dependent dielectric constant showed a dielectric anomaly, indicating the antiferromagnetic transition. The remanent polarization and the corresponding coercive field for x = 0.1 was found to be 0.0625 µC/cm2 and 56.154 kV/cm at an operating voltage of 1000 V. The improved electrical properties with low leakage current density were ascribed to the stabilization of the pervoskite structure and reduced oxygen vacancies.

In present work, cobalt substituted M-type barium nanoferrite of composition BaCo x Fe 12−x O 19 with x = 0.4, 0.8 and 1.0 were prepared via a co-precipitation method. After appropriate heat treatments the samples were characterized by X-ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RS) and Vector Network Analyzer (VNA). XRD confirmed the formation of pure single phase M-type barium ferrite with an average crystallite size in the range 65–85 nm. FESEM confirmed the formation of hexagonal platelets with an average grain size of in the range 250–325 nm. Vibrational bands at 466 cm −1 and 580 cm −1 confirmed the strong Me-O bond. Raman vibrational modes at 329 cm −1 and 676 cm −1 confirmed both, the strong Me-O bond and M-type barium ferrite formation. Electromagnetic properties were studied by measuring real part and imaginary part of permittivity and permeability in the frequency range of 12–18 GHz (Ku band). The maximum reflection loss of −45 dB was found to be at x = 1.0 which makes this composition a suitable candidate for Radar Absorbing Material (RAM) in Ku band.

In this paper, lamb wave acoustic (LWA) devices based on ZnO/Si plate of 30- $\mu \text{m}$ thickness have been fabricated. Devices with four different designs having acoustic wavelengths of 20, 40, 60, and $80~\mu \text{m}$ have been fabricated to study its effect on the acoustic velocity for both the lowest order antisymmetric ( $A_{0}$ ) and symmetric ( $S_{0}$ ) modes. The variation in effective phase difference in all the fabricated LWA devices is studied. An optimum device design is identified with appropriate distance between centers of the input and output IDTs to obtain a phase difference of 180° in antisymmetric and symmetric modes. The obtained phase difference of 180° is very critical in fabricating an oscillator for realization of wireless sensor devices. LWA devices offer high sensitivity to mass loading and thus hold tremendous potential for chemical sensing applications.

Fabrication of very thin GaN ultraviolet photodetectors on Si (111) substrate integrated with asymmetric (Pt–Ag, Pt–Cr) metal–semiconductor–metal (MSM) structure have been illustrated. Designed GaN photodetection device displays significant enhancement in responsivity for asymmetric (Pt–Ag) MSM structure (280 mA/W) in comparison to symmetric (Pt–Pt) MSM structure (126 mA/W) at 10 V bias. The fabricated asymmetric and symmetric devices also exhibit fast response time in the range of 30–59 ms. The enhancement in responsivity using asymmetric MSM structure ascribed to large difference in work function which lead to change in Schottky barrier height of the metal semiconductor junction. Additionally, power dependent photoresponse analysis of GaN asymmetric (Pt–Ag) ultraviolet photodetector was showing a responsivity of 116 mA/W at low optical power of 1 mW. Such GaN asymmetric MSM ultraviolet photodetectors having high responsivity can extensively be used for low power, high speed ultraviolet photo detection applications.

Eco-friendly lead-free relaxor ferroelectrics, Ba1-x (Bi0.5Li0.5)xTiO3 (BBLT) with x = 0.3, 0.4 and 0.5, have been synthesized by using the conventional solid-state reaction route. The crystal structure and phase purity were verified by x-ray diffraction (XRD) patterns using Rietveld refinement which revealed the presence of tetragonal (95–80%) and orthorhombic phases (5–20%) in the matrix. The temperature dependent dielectric constant and tangent loss dispersion spectra, slim ferroelectric-hysteresis, and nano-scale microstructures suggest the presence of short-range ordering (SRO)/polar nano-regions (PNRs) in the matrix. The dielectric spectra suggest that the dielectric dispersion increases with increase in Bi/Li concentrations which may be due to compositional fluctuations, ordering of cations at nano-scale and presence of metastable states of SRO and long-range ordering (LRO) regions. The nonlinear Vogel-Fulcher relationship is fitted for maximum dielectric constant temperatures (Tm) which provides activation energy and freezing temperature of all compositions. The current density (J) versus electric field (E) (J-E) data obey bulk-limited current conduction mechanisms that may be due to a diffusive displacement of Ti4+ at octahedral center, the creation of random fields due to in-homogeneity at A-site, and trap-assisted hoping of charge carriers under high E-fields.

Vogt Koyanagi Harada is a multisystem, granulomatous autoimmune disease with delayed onset of cutaneous manifestation. The case of an adolescent male with bilateral decreased vision is presented. The patient was diagnosed Vogt-Koyanagi-Harada (VKH) syndrome, with extraocular systemic manifestations in the form of sensory neural hearing loss (SNHL) and greying of scalp hairs at initial presentation which is very rare as cutaneous involvement usually occurs 2 to 3 months after the onset of disease. The syndrome may result in permanent visual loss but prompt treatment with corticosteroid therapy can restore vision. Therefore early ophthalmologic consultation must be sought. Keywords: Vogt-Koyanagi-Harada, Sensory neural hearing loss, Greying hairs.