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Gas sensors

Zhihua Wang, Changliang Hou, Qinma De, Fubo Gu, Dongmei Han
Uniform and monodisperse Co-doped In2O3 nanorods were fabricated by a facile and environmentally friendly hydrothermal strategy that combined the subsequent annealing process, and their morphology, structure and formaldehyde (HCHO) gas sensing performance were investigated systematically. Both pure and Co-doped In2O3 nanorods had a high specific surface area, which could offer abundant reaction sites to gas molecular diffusion and improve the response of gas sensor. Results revealed that the In2O3/1%Co nanorods exhibited a higher response of 23...
January 19, 2018: ACS Sensors
Chee-Loon Ng, Fuu-Ming Kai, Ming-Hui Tee, Nicholas Tan, Harold F Hemond
Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic) capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5) and volatile organic compounds (VOCs). For particulate matter testing, a test chamber was constructed and the emission of PM2...
January 18, 2018: Sensors
Bhavna Shamasunder, Ashley Collier-Oxandale, Jessica Blickley, James Sadd, Marissa Chan, Sandy Navarro, Michael Hannigan, Nicole J Wong
Oilfield-adjacent communities often report symptoms such as headaches and/or asthma. Yet, little data exists on health experiences and exposures in urban environments with oil and gas development. In partnership with Promotoras de Salud (community health workers), we gathered household surveys nearby two oil production sites in Los Angeles. We tested the capacity of low-cost sensors for localized exposure estimates. Bilingual surveys of 205 randomly sampled residences were collected within two 1500 ft. buffer areas (West Adams and University Park) surrounding oil development sites...
January 15, 2018: International Journal of Environmental Research and Public Health
Monika Kwoka, Barbara Lyson-Sypien, Anna Kulis, Monika Maslyk, Michal Adam Borysiewicz, Eliana Kaminska, Jacek Szuber
In this paper, the results of detailed X-ray photoelectron spectroscopy (XPS) studies combined with atomic force microscopy (AFM) investigation concerning the local surface chemistry and morphology of nanostructured ZnO thin films are presented. They have been deposited by direct current (DC) reactive magnetron sputtering under variable absolute Ar/O₂ flows (in sccm): 3:0.3; 8:0.8; 10:1; 15:1.5; 20:2, and 30:3, respectively. The XPS studies allowed us to obtain the information on: (1) the relative concentrations of main elements related to their surface nonstoichiometry; (2) the existence of undesired C surface contaminations; and (3) the various forms of surface bondings...
January 14, 2018: Materials
Rui Zhang, Tingting Zhou, Lili Wang, Tong Zhang
High sensitive and stable gas sensors have attracted much attention because they are the key to innovations in the fields of environment, health, energy savings and security, etc. Sensing materials, which influence the practical sensing performance, are the crucial parts for gas sensors. Metal-organic frameworks (MOFs) are considered as alluring sensing materials for gas sensors due to the possession of high specific surface area, unique morphology, abundant metal sites and functional linkers. Herein, four kinds of porous hierarchical Co3O4 structures have been selectively controlled by optimizing the thermal decomposition (temperature, rate and atmosphere) using ZIF-67 as precursor that was obtained from coprecipitation method with the co-assistant of cobalt salt and 2-methylimidazole in the solution of methanol...
January 17, 2018: ACS Applied Materials & Interfaces
Rui Han Gao, Zi-Yi Hua, Kai Chen, Jing Xu, Qian-Jiang Zhu, Zhu Tao, Jiang-Lin Zhao
Coordination supramolecular assemblies of monohydroxycucurbit[7]uril ((HO)Q[7]) with alkaline earth metal ions (AE2+) have been formed in aqueous HCl solution in the presence of tetrachloride cadmium anions ([CdCl4]2-) as a structure directing agent. The driving force for the assembly could be attributed to the interaction of the positive electro-potential outer-surface of (HO)Q[7] molecules with [CdCl4]2- anions and ionic dipole interaction of the hydroxyl of (HO)Q[7] molecules with [CdCl4]2- anions. Moreover, the porous structure of the (HO)Q[7]/AE2+-based coordination supramolecular assemblies could result in potential applications in the selective sorption of polar volatile organic molecules, which may be useful in molecular sieves, sensors, absorption and separation...
January 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Xiao-Long Liu, Suwan Zhu, Hai-Bin Sun, Yue Hu, Sheng-Xiang Ma, Xi-Jing Ning, Li Zhao, Jun Zhuang
The microstructured and hyperdoped silicon as a superior photoelectric and photovoltaic material is firstly studied as a gas-sensing material. The material is prepared by femtosecond-laser irradiation on Selenium-coated silicon and then fabricated as a conductive gas sensor targeting for ammonia. At room temperature, the sensitivity, response time, repeatability, distinguishability, selectivity, and natural aging effect of the sensor have been systematically studied. Results show that such black silicon has good potential for application as an ammonia-sensing material...
January 17, 2018: ACS Applied Materials & Interfaces
Koichi Suematsu, Nan Ma, Ken Watanabe, Masayoshi Yuasa, Tetsuya Kida, Kengo Shimanoe
To investigate the effect of aging at 580 °C in wet air (humid aging) on the oxygen adsorption on the surface of SnO₂ particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO₂ resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants (K₁; for O- adsorption, K₂; for O2- adsorption) were estimated on the basis of the theoretical model of oxygen adsorption...
January 16, 2018: Sensors
Liang Xu, Deting Xue, Xiaoyi Lv
A backward ray-tracing method is proposed for aero-optics simulation. Different from forward tracing, the backward tracing direction is from the internal sensor to the distant target. Along this direction, the tracing in turn goes through the internal gas region, the aero-optics flow field, and the freestream. The coordinate value, the density, and the refractive index are calculated at each tracing step. A stopping criterion is developed to ensure the tracing stops at the outer edge of the aero-optics flow field...
January 8, 2018: Optics Express
Faisal Nadeem, Berber R Postma, Geert Postma, Simona M Cristescu, Julien Mandon, Frans J M Harren
A 3D ray tracing model is used to simulate optical reinjection in a nonresonant optical cavity, for off-axis integrated cavity output spectroscopy. The optical cavities are optimized for maximum intensity enhancement factors via a grid search and a genetic algorithm. Intensity enhancement factors up to 1400 are found for short cavities (3 cm) and up to 101 for long cavities (50 cm). The model predicts that short absorption cells can be used, having a long effective path length and a high throughput power...
January 10, 2018: Applied Optics
D Cody, I Naydenova
The suitability of holographic structures fabricated in zeolite nanoparticle-polymer composite materials for gas sensing applications has been investigated. Theoretical modeling of the sensor response (i.e., change in hologram readout due to a change in refractive index modulation or thickness as a result of gas adsorption) of different sensor designs was carried out using the Raman-Nath theory and Kogelnik's coupled wave theory. The influence of a range of parameters on the sensitivity of holographically recorded surface and volume photonic structures has been studied, namely, hologram geometry, hologram thickness and spatial frequency, reconstruction wavelength, and zeolite nanoparticle refractive index...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Xiuzhan Xue, Ruixiao Wang, Linwen Lan, Jingming Wang, Zhongxin Xue, Lei Jiang
Gas bubbles in aqueous media are ubiquitous in a broad range of applications. In most cases, the size of bubbles must be manipulated precisely. However, it is very difficult to control the size of gas bubbles. The size of gas bubbles is affected by many factors both during and after the generation process. Thus, precise manipulation of gas bubble size still remains a great challenge. The ratchet and conical hairs of the Chinese brush enable it to realize a significant capacity for holding ink and transferring them onto paper continuously and controllably...
January 12, 2018: ACS Applied Materials & Interfaces
Xiaoyu Li, Kang Peng, Yewei Dou, Jiasheng Chen, Yue Zhang, Gai An
Wormhole-like mesoporous tin oxide was synthesized via a facile evaporation-induced self-assembly (EISA) method, and the gas-sensing properties were evaluated for different target gases. The effect of calcination temperature on gas-sensing properties of mesoporous tin oxide was investigated. The results demonstrate that the mesoporous tin oxide sensor calcined at 400 °C exhibits remarkable selectivity to ethanol vapors comparison with other target gases and has a good performance in the operating temperature and response/recovery time...
January 11, 2018: Nanoscale Research Letters
Lyudmila Nikitina, Roman Laptev, Yuri Abzaev, Andrey Lider, Alexander Ivashutenko
The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime...
January 11, 2018: Nanomaterials
Joan Roca, Miquel Nogués, Rafael Villalobos, María Carmen Mías, Martí Comellas, Cristina Gas, Jorge Juan Olsina
The closure of the abdominal wall after making a laparotomy is a major challenge for surgeons, since a significant percentage of closures fail and incisional hernias rise. The suture has to withstand the forces required to close the incision, while not hindering the adequate wound healing progression. Currently, there is no surgical measuring device that could be used to determine the required closing forces, which can be very different depending on the patient. This paper presents a dynamometer to measure the tension forces to be applied while closing a surgical incision, and it simultaneously measures the distance between wound edges...
January 11, 2018: Sensors
Juan Aponte-Luis, Juan Antonio Gómez-Galán, Fernando Gómez-Bravo, Manuel Sánchez-Raya, Javier Alcina-Espigado, Pedro Miguel Teixido-Rovira
This paper presents the design of a wireless sensor network particularly designed for remote monitoring and control of industrial parameters. The article describes the network components, protocol and sensor deployment, aimed to accomplish industrial constraint and to assure reliability and low power consumption. A particular case of study is presented. The system consists of a base station, gas sensing nodes, a tree-based routing scheme for the wireless sensor nodes and a real-time monitoring application that operates from a remote computer and a mobile phone...
January 10, 2018: Sensors
Ying Wang, Peng Gao, Linna Sha, Yurong Yang, Lei Yang, Jianjiao Zhang, Yujin Chen, Milin Zhang
The construction of semiconductor composites is known a powerful method to realize the spatial separation of electrons and holes in them, which can result in more electrons or holes and further realize more oxygen ions (O2- and O-) (one of the most critical factor for their gas-sensing properties) dispersing on the surface of semiconductor gas sensor. In this work, using one-dimensional ZnO/ZnSnO3 nanoarrays as an example, which are prepared through a hetero-epitaxial growing process to construct a chemically boned interface, the above strategy for better semiconductor gas-sensing preperty has been realized...
January 10, 2018: Nanotechnology
Chiu-Hsien Wu, Guo-Jhen Jiang, Kai-Wei Chang, Zu-Yin Deng, Yu-Ning Li, Kuen-Lin Chen, Chien-Chung Jeng
In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60-70 ppb also showed a good response. The resistance change (ΔR) and sensitivity (S) were linearly dependent on the ozone concentration. The response time (T90-res), recovery time (T90-rec), and time constant (τ) showed first-order exponential decay with increasing ozone concentration...
January 9, 2018: Sensors
Xiao Ling Zhang, Zhao Rong Tang, Yong Ping Dong, Cheng Ming Wang
Various kinds of ZnO nanoparticles have been successfully used in gas sensing applications, however, these nanomaterials have been rarely investigated in electrogenerated chemiluminescence (ECL). In the present work, ZnO nanorods (ZnONRs) were synthesized by hydrothermal method, and characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). ECL behaviors of ZnONRs were investigated in neutral aqueous condition in the presence of K2S2O8. Cyclic voltammetry (CV) results revealed that ZnONRs can react with K2S2O8 to generate strong light emission, revealing that K2S2O8 can act as coreactant of ZnONRs ECL...
March 1, 2018: Talanta
Ziying Wang, Tong Zhang, Chen Zhao, Tianyi Han, Teng Fei, Sen Liu, Geyu Lu
In this paper, we demonstrate room-temperature NO2 gas sensors using Pd nanoparticles (NPs) and SnO2 NPs decorated reduced graphene oxide (Pd-SnO2-RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO2 NPs with particle sizes of 3-5 nm are attached to RGO nanosheets. Compared to SnO2-RGO hybrids, the sensor based on Pd-SnO2-RGO hybrids exhibited higher sensitivity at room temperature, where the response to 1 ppm NO2 was 3.92 with the response time and recovery time being 13 s and 105 s...
December 28, 2017: Journal of Colloid and Interface Science
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