56 research outputs found
Insights into the Sensing Mechanism of a Metal-Oxide Solid Solution via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy
Recently, the influence of Nb addition in the oxide solid solution of Sn and Ti was investigated with regard to the morphological, structural and electrical properties for the production of chemoresistive gas sensors. (Sn,Ti,Nb)xO2-based sensors showed promising features for ethanol monitoring in commercial or industrial settings characterized by frequent variation in relative humidity. Indeed, the three-metal solid solution highlighted a higher response level vs. ethanol than the most widely used SnO2 and a remarkably low effect of relative humidity on the film resistance. Nevertheless, lack of knowledge still persists on the mechanisms of gas reaction occurring at the surface of these nanostructures. In this work, operando Diffuse Reflectance Infrared Fourier Transform spectroscopy was used on SnO2- and on (Sn,Ti,Nb)xO2-based sensors to combine the investigations on the transduction function, i.e., the read-out of the device activity, with the investigations on the receptor function, i.e., compositional characterization of the active sensing element in real time and under operating conditions. The sensors performance was explained by probing the interaction of H2O and ethanol molecules with the material surface sites. This information is fundamental for fine-tuning of material characteristics for any specific gas sensing applications
Sub-ppm NO2 Detection through Chipless RFID Sensor Functionalized with Reduced SnO2
NO2 is an important environmental pollutant and is harmful to human health even at very low concentrations. In this paper, we propose a novel chipless RFID sensor able to work at room temperature and to detect sub-ppm concentration of NO2 in the environment. The sensor is made of a metallic resonator covered with NO2-sensitive tin oxide and works by monitoring both the frequency and the intensity of the output signal. The experimental measurements show a fast response (a few minutes) but a very slow recovery. The sensor could therefore be used for non-continuous threshold monitoring. However, we also demonstrated that the recovery can be strongly accelerated upon exposure to a UV source. This opens the way to the reuse of the sensor, which can be easily regenerated after prolonged exposure and recycled several times
Fabrication of a Highly NO2-Sensitive Gas Sensor Based on a Defective ZnO Nanofilm and Using Electron Beam Lithography
Hazardous substances produced by anthropic activities threaten human health and the green environment. Gas sensors, especially those based on metal oxides, are widely used to monitor toxic gases with low cost and efficient performance. In this study, electron beam lithography with two-step exposure was used to minimize the geometries of the gas sensor hotplate to a submicron size in order to reduce the power consumption, reaching 100 °C with 0.09 W. The sensing capabilities of the ZnO nanofilm against NO2 were optimized by introducing an enrichment of oxygen vacancies through N2 calcination at 650 °C. The presence of oxygen vacancies was proven using EDX and XPS. It was found that oxygen vacancies did not significantly change the crystallographic structure of ZnO, but they significantly improved the electrical conductivity and sensing behaviors of ZnO film toward 5 ppm of dry air
Room Temperature Chemoresistive Gas Sensor Based on Organic-Functionalized Graphene Oxide
In the wide palette of chemoresistive sensing materials, hybrid nanocomposites have quickly gained [...
Roadmap on printable electronic materials for next-generation sensors
The dissemination of sensors is key to realizing a sustainable, âintelligentâ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our livesâe.g., via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g., printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuliâlight, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materialsâand devices thereofâto provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, âintelligentâ world
Sensori di gas, la precisione può essere anche low cost
Utilizzo di tecnologia a basso costo e di facile implementazione al servizio dei sistemi di supporto decisionale per lâagricoltura. Questo uno degli obiettivi del progetto âPositive â Protocolli operativi scalabili per lâagricoltura di precisioneâ, finanziato dal Bando Por-Fesr 2014-2020. Positive nasce dalla convinzione che la gestione ottimizzata e integrata della produzione agricola sia imprescindibile dallâesperienza sul campo, ma al contempo sia occasione di sviluppo tecnologico. Lo scopo è rendere disponibili su scala regionale indici di interesse agronomico ricavabili dalle immagini satellitari, affiancati dalle informazioni prodotte da una rete di sensori a terra e predisporre unâinfrastruttura informatica che renda concretamente fruibile su tutto il territorio regionale irrigazione e fertirrigazione di precisione
Applications of Chipless RFID Humidity Sensors to Smart Packaging Solutions
: Packaging solutions have recently evolved to become smart and intelligent thanks to technologies such as RFID tracking and communication systems, but the integration of sensing functionality in these systems is still under active development. In this paper, chipless RFID humidity sensors suitable for smart packaging are proposed together with a novel strategy to tune their performances and their operating range. The sensors are flexible, fast, low-cost and easy to fabricate and can be read wirelessly. The sensitivity and the humidity range where they can be used are adjustable by changing one of the sensor's structural parameters. Moreover, these sensors are proposed as double parameter sensors, using both the frequency shift and the intensity variation of the resonance peak for the measure of the relative humidity. The results show that the sensitivity can vary remarkably among the sensors proposed, together with the operative range. The sensor suitability in two specific smart packaging applications is discussed. In the first case, a threshold sensor in the low-humidity range for package integrity verification is analyzed, and in the second case, a more complex measurement of humidity in non-hermetic packages is investigated. The discussion shows that the sensor configuration can easily be adapted to the different application needs
A Novel Indium Oxide-Based Nanostructured Material Designed for CO2 Detection
Low-cost sensors working at low/room temperature for CO2 mapping in indoorâoutdoor environments are in growing demand. Solid-state gas sensors are a suitable alternative to expensive optical sensors, but to date, materials designed for chemoresistive devices have not proven functional for CO2 detection. This work addresses this challenge both in terms of sensing materials research, with the innovative use of alkali metals as dopants in semiconductors, and in terms of deeply understanding the sensing mechanism through DRIFT spectroscopy. The result is a sensor operating at 200 °C that detects CO2 between 250â5000 ppm with a negligible effect of humidity above 17 RH%
Nanomaterial-Based Electric and Electronic Gas Sensors
Great attention has been dedicated to the development and use of solid-state gas sensors based on nanostructured semiconductors in recent decades. Metal oxide semiconductors (MOSs) are definitely the most investigated materials, but they have shown several shortcomings, including the lack of selectivity and stability over time, which have limited their use in many applications. This has led researchers to design and synthesise advanced nanostructured materials based on other types of semiconductors, able to overcome the limitations of MOSs towards the development of devices with optimised sensing performance. Among several alternatives, nanostructured IIâVI transition metal chalcogenides (TMCs) are promising candidates for gas sensor development, due to their very interesting physicochemical features. These include: (i) wide and tunable bandgap; (ii) size-tunable radiation absorption and emission; (iii) catalytic and photocatalytic properties and (iv) the possibility to tune the nanostructure morphology and crystal structure by using simple and inexpensive methods. Although scarcely investigated in the gas sensing field so far, preliminary studies published over the last 10 years have shown peculiar sensing properties of TMCs, which could open up a future integration of these materials into commercial gas monitoring devices. This chapter presents a critical analysis of the state of the art related to the synthesis and use of IIâVI TMC nanomaterials (NMs) for the development of electrical and electronic gas sensors
Enhancing Ozone Monitoring with Low-Cost Sensors and Deep Neural Network: A Novel Approach
Ozone is a crucial component of the Earthâs atmosphere, playing a critical role in protecting the planet from harmful ultraviolet radiation. However, its concentration can vary greatly across different regions with significant impacts on human health and environment equilibrium. The aim of this work was to calibrate a low-cost sensing platform, based on chemoresistive gas sensors, to monitor the environmental concentration of O3. The ongoing on-field calibration is performed with a deep neural network using the concentration of O3 collected by the local environmental protection agencies through certified tools as the gold standard
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