Paper-Derived Ammonia Sensors Integrating A Natural Deep Eutectic Solvent

Ammonia is a naturally-occurring gas, present throughout the atmosphere at sub-ppb concentrations. As result of various processes, significantly higher concentrations can be found in the areas surrounding industrial and agricultural operations. In such cases, the presence of NH3 in air not only is associated with a very pungent odor and potential toxicity but can also affect the environment, animals, plants, and humans. Aiming to provide a simple platform to monitor NH3 in air, a paper-derived gas sensor, integrating a natural deep eutectic solvent (NADES) was developed. The herein described paper-derived ammonia gas sensor was fabricated using direct laser scribing, to form a carbon-based interdigitated array. Characterization and optimization (using chemometrics) were performed to develop a material with the lowest possible resistivity. A unique feature of the proposed sensor is that it integrates a natural deep eutectic solvent formed with lactic acid:glucose:water (LGH). This NADES conveys selectivity toward ammonia (over methanol, ethanol, 1-propanol, and water) and greatly enhances the sensitivity of the sensor (over the plain carbon array). The resistivity of the sensor was dependent on the NH3 concentration in the 0.11 – 40.6 % range and has an estimated limit of detection of 0.11 %. Although the sensitivity of the sensor is lower than that of others based on metallic oxides, this approach represents a low-cost, portable, and simple way to detect and measure ammonia in gas phase

Recent Advances in Applications of Ceramic Nanofibers

Ceramic materials are well known for their hardness, inertness, superior mechanical and thermal properties, resistance against chemical erosion and corrosion. Ceramic nanofibers were first manufactured through a combination of electrospinning with sol–gel method in 2002. The electrospun ceramic nanofibers display unprecedented properties such as high surface area, length, thermo-mechanical properties, and hierarchically porous structure which make them candidates for a wide range of applications such as tissue engineering, sensors, water remediation, energy storage, electromagnetic shielding, thermal insulation materials, etc. This chapter focuses on the most recent advances in the applications of ceramic nanofibers

Wearable Nano-Based Gas Sensors for Environmental Monitoring and Encountered Challenges in Optimization

With a rising emphasis on public safety and quality of life, there is an urgent need to ensure optimal air quality, both indoors and outdoors. Detecting toxic gaseous compounds plays a pivotal role in shaping our sustainable future. This review aims to elucidate the advancements in smart wearable (nano)sensors for monitoring harmful gaseous pollutants, such as ammonia (NH3), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), sulfur dioxide (SO2), ozone (O3), hydrocarbons (CxHy), and hydrogen fluoride (HF). Differentiating this review from its predecessors, we shed light on the challenges faced in enhancing sensor performance and offer a deep dive into the evolution of sensing materials, wearable substrates, electrodes, and types of sensors. Noteworthy materials for robust detection systems encompass 2D nanostructures, carbon nanomaterials, conducting polymers, nanohybrids, and metal oxide semiconductors. A dedicated section dissects the significance of circuit integration, miniaturization, real-time sensing, repeatability, reusability, power efficiency, gas-sensitive material deposition, selectivity, sensitivity, stability, and response/recovery time, pinpointing gaps in the current knowledge and offering avenues for further research. To conclude, we provide insights and suggestions for the prospective trajectory of smart wearable nanosensors in addressing the extant challenges

Multilayer Thin Films

This book, "Multilayer Thin Films-Versatile Applications for Materials Engineering", includes thirteen chapters related to the preparations, characterizations, and applications in the modern research of materials engineering. The evaluation of nanomaterials in the form of different shapes, sizes, and volumes needed for utilization in different kinds of gadgets and devices. Since the recently developed two-dimensional carbon materials are proving to be immensely important for new configurations in the miniature scale in the modern technology, it is imperative to innovate various atomic and molecular arrangements for the modifications of structural properties. Of late, graphene and graphene-related derivatives have been proven as the most versatile two-dimensional nanomaterials with superb mechanical, electrical, electronic, optical, and magnetic properties. To understand the in-depth technology, an effort has been made to explain the basics of nano dimensional materials. The importance of nano particles in various aspects of nano technology is clearly indicated. There is more than one chapter describing the use of nanomaterials as sensors. In this volume, an effort has been made to clarify the use of such materials from non-conductor to highly conducting species. It is expected that this book will be useful to the postgraduate and research students as this is a multidisciplinary subject

Ethanol Gas Sensor Fabrication Based on ZnO Flower Like Nanorods

Zinc oxide flower-like nanorods (ZnO NRs) was successfully synthesized via the hydrothermal method. The growth process was conducted with seed layer concentrations of 20mM. The as-synthesized nanostructures were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), and ultraviolet-visible (UV-VIS) spectrophotometer. The analysis results revealed a pure Wurtzite ZnO hexagonal nanostructures with preferred orientation (002) along the c-direction. The calculated band gap of average crystallite size is 3.2eV and 25 nm respectively. New designed, constructed and successfully calibrated for ethanol gas sensing was found. The ethanol gas sensor was fabricated at room temperature based on the ZnO NRs film. The synthesized materials proved to be a good candidate for the ethanol gas sensor. The optimum results of the gas sensor measurements of the synthesized gas sensor are as follows, the sensitivity, response time, and recovery time at 25 °C are 60%, 80 Seconds and 80 seconds respectively, and at 200 °C are 70%, 60 seconds and 50 seconds respectively

Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Multilayer Thin Films

This book, "Multilayer Thin Films-Versatile Applications for Materials Engineering", includes thirteen chapters related to the preparations, characterizations, and applications in the modern research of materials engineering. The evaluation of nanomaterials in the form of different shapes, sizes, and volumes needed for utilization in different kinds of gadgets and devices. Since the recently developed two-dimensional carbon materials are proving to be immensely important for new configurations in the miniature scale in the modern technology, it is imperative to innovate various atomic and molecular arrangements for the modifications of structural properties

Multilayer Thin Films

This book, "Multilayer Thin Films-Versatile Applications for Materials Engineering", includes thirteen chapters related to the preparations, characterizations, and applications in the modern research of materials engineering. The evaluation of nanomaterials in the form of different shapes, sizes, and volumes needed for utilization in different kinds of gadgets and devices. Since the recently developed two-dimensional carbon materials are proving to be immensely important for new configurations in the miniature scale in the modern technology, it is imperative to innovate various atomic and molecular arrangements for the modifications of structural properties

Flexible and Polymer-based CO2 Sensors for Food Packaging and Other Potential Applications

CO2 sensing is important in many applications ranging from air-quality monitoring to food packaging. Despite all the advancements in CO2 sensor technology, they are typically qualitative, bulky, expensive, and cross-sensitive to humidity, require high operating temperatures, external power sources, and complicated manufacturing processes making them incompatible with integration into food packaging. In light of this, the present study aims to develop chemiresistive, flexible, miniaturised, low-cost, lowpower, and simple-to-manufacture sensors capable of CO2 measurement at room temperature and high humidity conditions for food packaging and other potential applications. This thesis aims to develop chemiresistive, flexible, miniaturised, low-cost, low-power CO2 sensors for applications such as food packaging. The sensors are based on CO2-responsive polymers that change their electrical properties upon CO2 absorption. The interaction between CO2 and the polymer relies on acid-base chemistry, resulting in protonation of amine groups and altering the resistance. Initially, poly(N-[3-(dimethylamino)propyl] methacrylamide) (pDMAPMAm) is synthesised, but it exhibits irreversible response due to hindered proton hopping. To address this, poly(N-[3- (dimethylamino)propyl]-methacrylamide-co-2-N-morpholinoethyl methacrylate) (p(D-co-M)) with adjusted composition and basicity is developed, showing a reversible response to CO2. However, it has relatively long response and recovery times and cross-sensitivity to ammonia. To improve these shortcomings, a thin layer of Nafion-Na coating is applied to the p(D-co-M) sensor, denoted P-NafionNa sensors, reducing cross-sensitivity, shortening recovery time, and enabling Bluetooth® communication. The developed materials and sensors show promise for creating the next generation of miniaturised, flexible, wireless, and cost-effective CO2 sensors for various applications, including food quality monitoring