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In this work, NaYF4:Eu@TiO2:Er nanomaterial is synthesized via sol–gel method. Various characterization techniques such as FESEM, HRTEM, XRD, EDS FTIR and XPS confirmed the successful formation of NaYF4:Eu@TiO2:Er nanoparticles. The average particle size is found to be 15 nm. Also, UV–Vis–IR and PL spectrometry verified the biluminescent properties of the synthesized material. It is then investigated as biluminescent security ink to be used for anti-counterfeiting applications. The results showed that the designed biluminescent security ink exhibits strong yellow and purple emission under 275 nm and 325 nm excitations, respectively. A written material was kept for 3 months under hot (40 °C) and humid (85%) environment and the obtained results were identical without any deterioration in their luminescence intensities even after such a prolonged time. Moreover, this written material also showed stability under the exposure of different chemical solvents (ethanol, glycerol and acetone).

In this article, we have evaluated the performance of inverted organic solar cells (OSCs) fabricated under ambient air and inert environment. Here, poly([4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7) donor with [6,6]-phenyl C70-butyric acid methyl ester (PC71BM) acceptor were employed as a photoactive layer. The calculated power conversion efficiency (PCE) from current–voltage (J–V) characteristics for a device fabricated under an inert environment is 6.90% as compared to 3.96% for a device fabricated in ambient condition (25 °C, 100 kPa). The results revealed that the device processed in ambient conditions degrades the photovoltaic performance parameters, and the PCE decreased by 42.62% as compared to the devices fabricated in an inert environment. Along with this, we have also discussed in detail, the effect of the working environment on photoactive layers by Raman spectroscopy. The UV–Vis spectroscopy and Atomic Force Microscopy (AFM) techniques are presented to illustrate the optical properties and morphology of the photo-active layer respectively.

This paper presents new gyroscope design architecture with the complete 2-DOF drive and 1-DOF sense mode oscillators that enable the implementation of reduced drive bandwidth without significantly decreasing the sense-to-drive mass ratio of the device. The mechanical structure has an additional anchoring of the decoupling frame mass which allows for the specification of the drive mode resonances and the coupling between the masses independent of the sense mode frequency. This feature eliminates the requirement of an increased design space for realizing a high operational frequency device with robust operation. In addition to this, a reduction in the bandwidth enabled by the additional anchor, leads to the increase in drive mass amplitude, which in turn results in an increased mechanical gain. With this arrangement, the actuation voltage can be further reduced for the same drive displacement as of non-anchored structure. This device has been mathematically modelled considering decoupled frame anchoring effect, designed and then fabricated by using the economical UV-LIGA technology with nickel as a key structural layer of 8 µm thickness; with an overall reduced key structure size of 2.13 by 1.93 mm. Experimental characterization demonstrates the two drive resonances at 8.55 and 10.6 kHz with a bandwidth of 1.0 kHz and the sense mode resonance at 9.2 kHz.

In this paper, ZnO nano thin film is prepared on n-type Si substrate with orientation using RF sputtering technique and a surface acoustic wave (SAW) based fluorine (F2) gas sensor integrated on ZnO with Palladium (Pd) on top as sensing layer is fabricated and characterized. The input and output interdigital transducer is fabricated of aluminum (Al) using nanolithography technique. The morphological characterization of ZnO thin film is done using scanning electron microscopy and atomic force microscopy. The XRD confirms the formation of ZnO nanostructured thin film. The voltage handling capability of the fabricated device is evaluated with negative and positive bias voltage. The study confirms that the SAW sensor based on ZnO/Si substrate and Pd sensing layer has good characteristic response of F2 gas with different concentration of gas from 0.5 to 20 ppm. The sensor shows good reproducibility and its sensitivity is approximately 2.4 kHz ppm?1.

In this paper, we present a new analytical model for frequency as well as transient analysis of a 3-DOF gyro-accelerometer system having 2-DOF in drive and 1-DOF in sense direction respectively. The model constructs lumped parameter differential equations by vector analysis associated with each degree of freedom that comprises Coriolis action, Euler's action and action due to external acceleration along with biasing counterparts. These coupled differential equations are then solved explicitly in the frequency domain by taking their Laplace transforms. Based on these formulations, a thorough system analysis has been carried out keeping in view the various parameters and issues related to the device design. Furthermore, a discriminating scheme for time varying angular rate and linear acceleration by combining the structural model of a gyro-accelerometer with the demodulation and filtering processes to investigate frequency response of a micro gyro-accelerometer has also been presented by taking into account the presently derived settled transient solution of sense mode response. Finally we have verified the present model with MATLAB Simulink, showing their excellent agreement with each other.