Highly sensitive, room temperature operated gold nanowire-based humidity sensor: adoptable for breath sensing

A novel, highly sensitive gold nanowire (AuNW) resistive sensor is reported here for humidity sensing in the relative humidity range of 11% to 92% RH as well as for breath sensing.

Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

Intensity variation of gamma radiation on ground level interface in São Jose dos Campos, SP, Brazil

In the period June 22 to September 24, 2012 São José dos Campos region experienced dry climate with low relative humidity. The net rain intensity measured in this period was 60 mm/h and the relative humidity range between 30% to 40% on most days. The intensity of gamma radiation from 0.03 to 10.0 MeV, in the measurement period presents a daily fluctuation well clearly, and some small increases when there is rainfall. These measures were realized at ITA's campus with a scintillator of NaI(Tl), photomultiplier and associated electronics laptop to a Dell 630 PC. A data acquisition interface purchased from (Aware Eletronics, USA) provides a file with measurements versus time, in the range from minute to minute recorded in txt. It was observed that the variation of gamma radiation in the interface soil/air at the region is originating from the local radon gas dynamics and of the presence of wind shear near the ground level. No período de 22 de junho a 24 de setembro de 2012, a região de São José dos Campos experimentou um clima seco com baixa umidade relativa. A intensidade líquida de chuva medida neste período foi de 60 mm/h e a umidade relativa varia entre 30% a 40% na maioria dos dias. A intensidade de radiação gama de 0,03 a 10,0 MeV, no período de medição apresenta uma flutuação diária bem clara, e alguns pequenos aumentos quando há chuva. Estas medidas foram realizadas no campus da ITA com um cintilador de NaI(Tl), fotomultiplicador e laptop eletrônico associado a um PC Dell 630. Uma interface de aquisição de dados adquirida da (Aware Eletronics, EUA) fornece um arquivo com medidas versus tempo, na faixa de minutos a minutos gravados em txt. Foi observado que a variação da radiação gama na interface solo/ar na região é originada pela dinâmica local do gás radônio e da presença de cisalhamento do vento próximo ao nível do solo.

A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8–98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

The Effect of Au Nanoparticle Addition on Humidity Sensing with Ultra-Small TiO2 Nanoparticles

In this paper, we investigate humidity sensing through impedance measurements with TiO2 nanoparticles (about 6 nm in diameter). The transient behavior and the impedance spectra are measured and interpreted from the theoretical point of view. Large responses are shown especially in the relative humidity range from 30% to 80%, which are essentially explained by condensation in the nanopores. The effect of the addition of Au nanoparticles is investigated and as expected, the Au/TiO2 interfaces allow for dramatically reducing the sensing film response time and above all, its recovery time; moreover, it seems to favor condensation when the relative humidity overcomes 70%.

Effect of Relative Humidity on Mycelial Growth of Cercospora canescens

The relative humidity studies revealed that maximum mycelial of fungus was observed at 90 per cent relative humidity (89.00 mm), which was followed by 100 per cent (86.30 mm). The least mycelia growth was observed at 50 per cent (45.30 mm). A significant decrease in mycelium growth was observed at 80, 70 and 60 per cent (80.40 mm, 70.20 mm and 57.00 mm) humidity level, respectively. Each fungus has its relative humidity range for the growth.

Mechanochemical reactions of GaN-Al2O3 interface at the nanoasperity contact: Roles of crystallographic polarity and ambient humidity

Mechanochemical reactions of the GaN-Al2O3 interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al2O3 nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism of the selective water-involved mechanochemical removal is associated with the dangling bond configuration, which affects the mechanically-stimulated chemical reactions via altering the activation energy barrier to form the bonding bridge across the sliding interface. These findings can enrich the understanding of the underlying mechanism of mechanochemical reactions at GaN-Al2O3 interface and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.

Intensity variation of gamma radiation on ground level interface in São Jose Dos Campos, SP, Brazil

In the period June 22 to September 24, 2012 São José dos Campos region experienced dry climate with low relative humidity. The net rain intensity measured in this period was 60 mm/h and the relative humidity range between 30% to 40% on most days. The intensity of gamma radiation from 0.03 to 10.0 MeV, in the measurement period presents a daily fluctuation well clearly, and some small increases when there is rainfall. These measures were realized at ITA's campus with a scintillator of NaI(Tl), photomultiplier and associated electronics laptop to a Dell 630 PC. A data acquisition interface purchased from (Aware Eletronics, USA) provides a file with measurements versus time, in the range from minute to minute recorded in txt. It was observed that the variation of gamma radiation in the interface soil/air at the region is originating from the local radon gas dynamics and of the presence of wind shear near the ground level.

Coexistence of three liquid phases in individual atmospheric aerosol particles

Individual atmospheric particles can contain mixtures of primary organic aerosol (POA), secondary organic aerosol (SOA), and secondary inorganic aerosol (SIA). To predict the role of such complex multicomponent particles in air quality and climate, information on the number and types of phases present in the particles is needed. However, the phase behavior of such particles has not been studied in the laboratory, and as a result, remains poorly constrained. Here, we show that POA+SOA+SIA particles can contain three distinct liquid phases: a low-polarity organic-rich phase, a higher-polarity organic-rich phase, and an aqueous inorganic-rich phase. Based on our results, when the elemental oxygen-to-carbon (O:C) ratio of the SOA is less than 0.8, three liquid phases can coexist within the same particle over a wide relative humidity range. In contrast, when the O:C ratio of the SOA is greater than 0.8, three phases will not form. We also demonstrate, using thermodynamic and kinetic modeling, that the presence of three liquid phases in such particles impacts their equilibration timescale with the surrounding gas phase. Three phases will likely also impact their ability to act as nuclei for liquid cloud droplets, the reactivity of these particles, and the mechanism of SOA formation and growth in the atmosphere. These observations provide fundamental information necessary for improved predictions of air quality and aerosol indirect effects on climate.