The article aims to optimize the inkjet printing properties to realize highly conductive and mechanically stable printed patterns on the Polyethylene terephthalate (PET) substrate. The key printing parameters such as drop spacing, the number of printed layers, and sintering temperatures were investigated. The test specimens were printed using silver nanoparticle ink and Dimatix 2831 inkjet printer. Then, the printed samples were characterized by electrical conductivity, bending, and adhesion tests. The Analysis of Variance (ANOVA) analysis showed that the number of layers and sintering temperatures were significant factors (p < 0.05) affecting electrical conductivity. The optimum printing parameters for the PET substrate were found to be 20 μm drop spacing, three layers of printing, and 120°C sintering temperature for 30 minutes. The measured optimum resistivity was found to be 5.25 μ -cm. The repetitive bending and adhesion test and ASTM tape test indicated good mechanical stability.
Electroencephalogram (EEG) signals have great importance in the area of brain-computer interface (BCI) which has diverse applications ranging from medicine to entertainment. BCI acquires brain signals, extracts informative features and generates control signals from the knowledge of these features for functioning of external devices. The objective of this work is twofold. Firstly, to extract suitable features related to hand movements and secondly, to discriminate the left and right hand movements signals finding effective classifier. This work is a continuation of our previous study where beta band was found compatible for hand movement analysis. The discrete wavelet transform (DWT) has been used to separate beta band of the EEG signal in order to extract features. The performance of a probabilistic neural network (PNN) is investigated to find better classifier of left and right hand movements EEG signals and compared with classical back propagation based neural network. The obtained results shows that PNN (99.1%) has better classification rate than the BP (88.9%). The results of this study are expected to be helpful in brain computer interfacing for hand movements related bio-rehabilitation applications.
This study proposes a coplanar waveguide‐fed circular monopole antenna that is designed by ink‐jetting conductive silver particle ink on photo paper. The antenna comprises a slotted circular patch and a reduced symmetrically slotted ground plane that is etched rectangularly. The slotted circular patch and ground plane provide the design flexibility with a broad bandwidth, substantial gain over 1.66–56.1 GHz frequency band, and relatively consistent radiation pattern. The fractional bandwidth (%BW) of this antenna is 188.5% that is covering industrial, scientific, and medical (ISM) bands, ultra‐wideband, wireless local area network (WLAN) band, worldwide interoperability for microwave access (WiMAX) band, and various frequencies of upcoming fifth‐generation technology. The total size of the antenna is only 34 × 25 mm2, with an electrical dimension of 0.18 λ × 0.13 λ at 1.66 GHz. The bandwidth ratio (BR) is 33.81:1, and the bandwidth dimension ratio (BDR) is 7462, which is the highest among the flexible super‐wideband antennas reported so far. It is a low profile, lightweight, and low‐cost antenna that is accommodating a broad frequency spectrum for extended wideband communication. The measured results show good agreement with the simulations.
In this article, a new wideband bowtie shaped slot antenna is realized on a flexible polyethylene terephthalate (PET). The slotted bowtie design is implemented with an asymmetric bowtie flare angle and a larger feeding neck with a metal strip inside the bowtie slot to achieve a wider bandwidth and a higher gain. The designed free space antenna is fabricated using inkjet printing and tested. The fabricated antenna operates over 2.1-4.35 GHz frequency range (69.77% fractional bandwidth) which covers WLAN, WiMax, and most of the 3G and 4G frequency bands. Further, the antenna exhibits an omnidirectional radiation pattern with a peak gain of 6.3 dBi at 4.35 GHz. The bending test of the fabricated device reveals adequate flexibility without significant antenna performance degradation. Moreover, the antenna tunability for any mounting structure application is also investigated by simulating another version of the parent antenna (free space antenna) for drywall mounting applications. The tuned antenna covers a similar frequency band as a free space antenna maintaining the desired radiation performances. The compact size, higher bandwidth, omnidirectional pattern with a higher peak gain and flexible properties make the antenna design suitable for mounting structure for Internet of Things (IoT) applications.
An electrochemical sensor for the detection of extremely low concentration of ammonia (1 part per billion, ppb) was fabricated by integrating vanadium monoxide (VOx; x = 0.8–1.2) nanowires on the platinum electrodes. The nanowire-based sensor responds at room temperature non-linearly to a staircase sequence of ammonia from 1 ppb to 100 ppb. The rise and fall time of the nanowire sensor was found to be 10 s and 9 s, respectively. While the immobilization of VO nanowires increased the electrochemical surface area, the defect rich and ionic nature of the VO surface (V2+O2−) facilitated the chemical interaction and adsorption of polar ammonia molecules as evident in the room temperature response of the VO@Pt amperometric electrochemical sensor. The availability of metal centered d-electrons and the semiconductor nature of vanadium monoxide lowered the interfacial resistance of the nanowire-modified sensor enabling the lower detection limit of ammonia. The sensor seems to respond to CH4, H2S and C3H6 as well although the NH3 response is nearly six-fold compared to these common interfering compounds. The results pave the way for a low-cost alternative paper-based sensor to monitor ammonia emissions primarily from confined animal feeding operations (CAFOs).
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