Nickel Oxide-based Flexible Thin-Film NTC Thermistors by using reverse offset printing

In recent years, the use of printing methods to fabricate electronic devices (printed electronics) has attracted attention because of their low cost and low environmental impact. Printing technology enables the high-throughput fabrication of electrical circuits on film substrates, providing inexpensive personal healthcare devices to monitor health status in real-time. Temperature detection is one of the central concerns as a fundamental physical quantity in various fields. In 2013, a highly sensitive flexible thermistor was reported by formulating aqueous inks of nickel oxide nanoparticles for inkjet printing. However, the calcinating of the nickel oxide (NiO) layer required a high-temperature process of more than 200°C, which required expensive polyimide films with high heat resistance. It is necessary to promote further the development of low-temperature processes for printed thermistors to realize flexible NTC thermistors at low cost using printed electronics technology. In screen printing and inkjet printing, the definition of the ink pattern applied on the substrate changes due to spreading and coffee distortion phenomena, and the thickness between sensors becomes non-uniform, which is a structural consistency problem that can lead to variations in sensing performance. This study developed a printing and low-temperature calcinating method of NTC thermistors with a temperature-sensitive layer of nickel oxide by using reverse offset printing. The NTC thermistors were fabricated by printing a comb-like pattern of silver nanoparticles and a thin nickel oxide film on a glass substrate. In addition, the low-temperature formation of a nickel oxide layer by oxygen plasma treatment was investigated, and XPS was used to carry out compositional analysis of the surface. Together with the plasma-assisted calcinating, a flexible NTC thermistor formed on polyethylene terephthalate (PEN) film is demonstrated.

Exposure to Nickel Oxide Nanoparticles Induces Acute and Chronic Inflammatory Responses in Rat Lungs and Perturbs the Lung Microbiome

Nickel oxide nanoparticles (NiO NPs) are highly redox active nanoparticles. They can cause acute and chronic inflammation in rat lungs. Unlike the gut microbiome, the association between the lung microbiome’s role and pulmonary inflammatory response to inhaled nanoparticles remains largely unexplored. We aimed to explore the interaction between the lung microbiome and inflammatory responses in rats exposed to NiO NPs. Thirty female Wistar rats were randomly categorized into control and low- (50 cm2/rat), and high- (150 cm2/rat) dose NiO NPs exposure groups. NiO NPs were intratracheally instilled, and cytological, biochemical, proinflammatory cytokine, and lung microbiome analyses of bronchoalveolar lavage fluid were performed at 1 day and 4 weeks after instillation. NiO NPs caused a neutrophilic and lymphocytic inflammatory response in rat lung. We demonstrated that exposure to NiO NPs can alter the lung microbial composition in rats. In particular, we found that more Burkholderiales are present in the NiO NPs exposure groups than in the control group at 1 day after instillation. Dysbiosis in the lung microbiome is thought to be associated with acute lung inflammation. We also suggested that Burkholderiales may be a key biomarker associated with lung neutrophilic inflammation after NiO NPs exposure.

Suaeda maritima (L.) Dumort GREEN SYNTHESIS- REDUCED NICKEL OXIDE NANOPARTICLES FOR ANTIOXIDANT AND BACTERICIDAL ACTIVITY

A unique way, green, cost-effective, and direct fabrication method is proposed for the synthesis of Nickel Oxide Nanoparticles (NPs) in an eco-environmentally way through leaf extract of Suaeda maritima (L.) Dumort. The nickel oxide nanoparticles were synthesized using Nickel (II) nitrate hexahydrate as a metal source and aqueous leaf extract of S. maritima was utilized as a green reducing agent. The formation of NPs was monitored by the change in color in the reaction mixture and the synthesized NPs were characterized using UV-visible spectrophotometer, Fourier Transform infrared (FT-IR) spectroscopy, field emission scanning electron microscope (FE SEM), X-ray diffractometer (XRD), and energy-dispersive X-ray spectroscopy (EDX). Further, the antibacterial activity of synthesized NPs was carried using the agar plate well diffusion method and antioxidant activity by DPPH free radical scavenging activity of the NPs was studied. The UV-visible absorption spectra of nanoparticles show a characteristic maximum absorption peak centered at 397 nm. The functional group analysis by FT-IR confirms the presence of various bio-active functional groups in the synthesized particles. The structural characterization confirms that the particles were Face Centred Cubic lattice structure having IR-regular in shape and rough surface with average atomic weight percentages of 76.3%. The synthesized nanoparticles were found to be potent against the growth of gram-positive (Bacillus subtilis, Staphylococcus aureus) and gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. In the DPPH assay, the IC 50 values of the synthesized NPs were found to be 28.01 μg/mL which is very close to standard ascorbic acid (22.19 μg/mL) whereas the IC 50 of the aqueous plant leaf extract was found to be 47.30 μg/m confirms that the nanoparticles having enhanced antioxidant activity. From the results of the study it can be concluded that this protocol is simple, rapid, one step, eco-friendly, non-toxic for the synthesis of nickel nanoparticles.

Phytochemical-Assisted Green Synthesis of Nickel Oxide Nanoparticles for Application as Electrocatalysts in Oxygen Evolution Reaction

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and particle size is a crucial aspect in designing a highly efficient nanomaterials-based electrocatalyst for water splitting. Herein, green synthesis of nickel oxide nanoparticles using phytochemicals from three different sources was employed to synthesize nickel oxide nanoparticles (NiOx NPs). Nickel (II) acetate tetrahydrate was reacted in presence of aloe vera leaves extract, papaya peel extract and dragon fruit peel extract, respectively, and the physicochemical properties of the biosynthesized NPs were compared to sodium hydroxide (NaOH)-mediated NiOx. Based on the average particle size calculation from Scherrer’s equation, using X-ray diffractograms and field-emission scanning electron microscope analysis revealed that all three biosynthesized NiOx NPs have smaller particle size than that synthesized using the base. Aloe-vera-mediated NiOx NPs exhibited the best electrocatalytic performance with an overpotential of 413 mV at 10 mA cm−2 and a Tafel slope of 95 mV dec−1. Electrochemical surface area (ECSA) measurement and electrochemical impedance spectroscopic analysis verified that the high surface area, efficient charge-transfer kinetics and higher conductivity of aloe-vera-mediated NiOx NPs contribute to its low overpotential values.