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Flexible gas sensor

Ana Rovisco, Rita Branquinho, Jorge Martins, Maria João Oliveira, Daniela Nunes, Elvira Fortunato, Rodrigo Martins, Pedro Barquinha
Semiconductor nanowires are mostly processed by complex, expensive, and high temperature methods. In this work, with the intent of developing zinc tin oxide nanowires (ZTO NWs) by low-cost and low-complexity processes, we show a detailed study on the influence of chemical parameters in the hydrothermal synthesis of ZTO nanostructures at temperatures of only 200 °C. Two different zinc precursors, the ratio between zinc and tin precursors, and the concentration of the surfactant agent and of the mineralizer were studied...
August 24, 2018: ACS applied nano materials
Murilo Santhiago, Priscila G da Costa, Mariane P Pereira, Cátia C Corrêa, Vitória B de Morais, Carlos C B Bufon
The synergic combination of materials and interfaces to create novel functional devices is a crucial approach for various applications, including low-cost paper-based point-of-care systems. In this work, we demonstrate the implementation of surface-modified polypyrrole (PPy) structures, monolithically integrated into a three-dimensional multilayered paper-based microfluidic device, to locally assess humidity changes. The fabrication and integration of the system include the deterministic incorporation of PPy into the paper-based structure by gas-phase polymerization and the modification of the polymer properties to allow local humidity monitoring...
October 8, 2018: ACS Applied Materials & Interfaces
Kyung Yong Ko, Sangyoon Lee, Kyunam Park, Youngjun Kim, Whang Je Woo, Donghyun Kim, Jeong-Gyu Song, Jusang Park, Jung Hwa Kim, Zonghoon Lee, Hyungjun Kim
Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted considerable attention as promising building blocks for a new generation of gas-sensing devices because of their excellent electrical properties, superior response, flexibility, and low-power consumption. Owing to their large surface-to-volume ratio, various 2D TMDCs, such as MoS2 , MoSe2 , WS2 , and WSe2 , have exhibited excellent gas-sensing characteristics. However, exploration toward the enhancement of TMDC gas-sensing performance has not yet been intensively addressed...
October 10, 2018: ACS Applied Materials & Interfaces
Weiwei Li, Changjiu Teng, Yilin Sun, Li Cai, Jian-Long Xu, Mengxing Sun, Xian Li, Xiaokuo Yang, Lan Xiang, Dan Xie, Tianling Ren
Flexible chemical sensors usually require transfer of prepared layers or whole device onto special flexible substrates and further attachment to target objects, limiting the practical applications. Herein, a sprayed gas sensor array utilizing silver nanoparticles (AgNPs)-all-carbon hybrid nanostructures is introduced to enable direct device preparation on various target objects. The fully flexible device is formed using metallic single-walled carbon nanotubes as conductive electrodes and AgNPs-decorated reduced graphene oxide as sensing layers...
October 10, 2018: ACS Applied Materials & Interfaces
Ming Chen, Zhenkai Li, Weimin Li, Chengwei Shan, Wenjie Li, Kaiwei Li, Guoqiang Gu, Ye Feng, Guohua Zhong, Lei Wei, Chunlei Yang
Advances in two-dimensional semiconducting thin films enable the realization of wearable electronic devices in the form factor of flexible substrate/thin films that can be seamlessly adapted in our daily lives. For wearable gas sensing, two-dimensional materials, such as SnSe2 , are particularly favorable because of their high surface-to-volume ratio and strong adsorption of gas molecules. Chemical vapor deposition and liquid/mechanical exfoliation are the widely applied techniques to obtain SnSe2 thin films...
November 9, 2018: Nanotechnology
Debasis Maity, Ramasamy Thangavelu Rajendra Kumar
Polyaniline (PANI) functionalized multiwall carbon nanotubes (MWCNTs) were prepared via in situ chemical polymerization process of aniline, in which MWCNTs were spray coated on the fabric for wearable ammonia sensor. Structural, morphological, thermal properties and wettability were analyzed by scanning electron microscope, X-ray diffraction, Raman analysis and contact angle measurement. No substantial change in base resistance of MWCNTs/PANI fabric sensor was observed for a wide range of bending (from 90° to 270°) shows excellent wearability...
September 28, 2018: ACS Sensors
Florin C Loghin, Aniello Falco, Andreas Albrecht, José F Salmerón, Markus Becherer, Paolo Lugli, Almudena Rivandeneyra
In this study, we report on an automated method based on a handwritten technique for the fabrication of low-cost gas sensors based on carbon nanotube (CNT) networks. Taking advantage of the inherent low-cost, flexible, and uncomplicated characteristics of pen-based techniques and combining them with an automated robotic system allows for high-resolution patterns, high reproducibility, and relatively high throughput considering the limitations of parallel processing. To showcase this, gas sensors capable of sensing NH3 , CO2 , CO, and ethanol, as well as temperature and relative humidity, are fabricated and characterized displaying competitive performance in relation to previously reported devices...
October 10, 2018: ACS Applied Materials & Interfaces
Do-Kyun Kwon, Yoann Porte, Kyung Yong Ko, Hyungjun Kim, Jae-Min Myoung
Flexible zinc oxide (ZnO) nanorod (NR) ultraviolet (UV)/gas dual sensors using silver (Ag) nanoparticle (NP) templates were successfully fabricated on a polyimide substrate with nickel electrodes. Arrays of Ag NPs were used as a template for the growth of ZnO NRs, which could enhance the flexibility and the sensing properties of the devices through the localized surface plasmon resonance (LSPR) effect. The Ag NPs were fabricated by the rapid thermal annealing process of Ag thin films, and ZnO NRs were grown on Ag NPs to maximize the surface area and form networks with rod-to-rod contacts...
September 19, 2018: ACS Applied Materials & Interfaces
Ye Tian, Jianchun Wang, Liqiu Wang
We present a gas-in-water microfluidic method to precisely fabricate well-controlled versatile microfibers with cavity knots (named cavity-microfiber), like tiny-cavity-microfiber, hybrid-cavity-microfiber, cavity-microfiber, and chained microfiber. The cavity-microfibers are endowed with tunable morphologies, unique surface properties, high specific surface area, assembling ability, flexibility, cytocompatibility, and hydroscopicity. We assemble cavity-microfibers as 3D scaffolds for culturing the human umbilical vein endothelial cells (HUVECs) and dehumidifying...
September 5, 2018: ACS Applied Materials & Interfaces
Jeongsu Kim, Haneul Yoo, Viet Anh Pham Ba, Narae Shin, Seunghun Hong
We report a colorimetric dye-functionalized sol-gel matrix on carbon nanotubes for use as a refreshable and flexible gas sensor with humidity calibration. Here, we fabricated gas sensors by functionalizing dye molecules on the top of carbon nanotube networks via a sol-gel method. Using hybrid gas sensors with different dye molecules, we could selectively detect various hazardous gases, such as NH3 , Cl2 and SO2 gases, via optical and electrical signals. The sensors exhibited rather large conductance changes of more than 50% following exposure to gas species with concentrations even under the permissible exposure limit...
August 10, 2018: Scientific Reports
Hua-Yao Li, Chul-Soon Lee, Do Hong Kim, Jong-Heun Lee
Ammonia (NH3 ) is an irritant gas with a unique pungent odor; sub-parts per million-level breath ammonia is a medical biomarker for kidney disorders and Helicobacter pylori bacteria-induced stomach infections. The humidity varies in both ambient environment and exhaled breath, and thus humidity dependence of gas-sensing characteristics is a great obstacle for real-time applications. Herein, flexible, humidity-independent, and room-temperature ammonia sensors are fabricated by the thermal evaporation of CuBr on a polyimide substrate and subsequent coating of a nanoscale moisture-blocking CeO2 overlayer by electron-beam evaporation...
August 22, 2018: ACS Applied Materials & Interfaces
Xin Zhang, Qi Zhang, Dan Yue, Jun Zhang, Jintong Wang, Bin Li, Yu Yang, Yuanjing Cui, Guodong Qian
Metal-organic framework (MOF)-polymer mixed-matrix membranes (MMMs) have shown great potential and superior performance in gas separations. However, their sensing application has not been fully established yet. Herein, a rare example of using flexible MOF-based MMMs as a fluorescent turn-on sensor for the detection of hydrogen sulfide (H2 S) is reported. These MOF-based MMMs are readily prepared by mixing a highly stable aluminum-based nano-MOF (Al-MIL-53-NO2 ) into poly(vinylidene fluoride) with high loadings up to 70%...
September 2018: Small
Shoyebmohamad F Shaikh, Balaji G Ghule, Umesh T Nakate, Pritamkumar V Shinde, Satish U Ekar, Colm O'Dwyer, Kwang Ho Kim, Rajaram S Mane
A low-temperature (90 °C) and directly grown anatase titanium dioxide (TiO2 ) nanocrystalline film using successive ionic layer adsorption and reaction (SILAR) for perovskite solar cell and gas sensor applications. TiO2 nanocrystalline electron transfer layer (ETL) improves the power conversion efficiency (PCE) of perovskite solar cells due to faster charge transport kinetics as well as slower charge recombination process. The optimized TiO2 nanocrystalline ETL (15 L) demonstrates as high as ~10% PCE with a short circuit current density of 18...
July 20, 2018: Scientific Reports
Mostafa Haghi, Regina Stoll, Kerstin Thurow
A novel hardware approach with four physical layers and several integrated and add-on sensors for a comprehensive physical and chemical environmental parameter (toxic gases, sound level, air pressure, humidity, temperature, and motion tracking) monitoring is introduced in this paper. To provide flexibility, the system is modular and each sensor functions independently. The whole solution is small, compact, light, and wrist worn. It is working in low power consumption mode and operates for several hours. The device has two layers to implement the sensors and one layer for a warning system driver to enable the vibrating motor and beeper in emergency status...
July 16, 2018: IEEE Transactions on Biomedical Circuits and Systems
Chang Liu, Béla Tuzson, Philipp Scheidegger, Herbert Looser, Bernhard Bereiter, Manuel Graf, Morten Hundt, Oleg Aseev, Deran Maas, Lukas Emmenegger
High precision mobile sensing of multi-species gases is greatly demanded in a wide range of applications. Although quantum cascade laser absorption spectroscopy demonstrates excellent field-deployment capabilities for gas sensing, the implementation of this measurement technique into sensor-like portable instrumentation still remains challenging. In this paper, two crucial elements, the laser driving and data acquisition electronics, are addressed. Therefore, we exploit the benefits of the time-division multiplexed intermittent continuous wave driving concept and the real-time signal pre-processing capabilities of a commercial System-on-Chip (SoC, Red Pitaya)...
June 2018: Review of Scientific Instruments
Andrew M Ullman, Christopher G Jones, F Patrick Doty, Vitalie Stavila, A Alec Talin, Mark D Allendorf
Because of their extraordinary surface areas and tailorable porosity, metal-organic frameworks (MOFs) have the potential to be excellent sensors of gas-phase analytes. MOFs with open metal sites are particularly attractive for detecting Lewis basic atmospheric analytes, such as water. Here, we demonstrate that thin films of the MOF HKUST-1 can be used to quantitatively determine the relative humidity (RH) of air using a colorimetric approach. HKUST-1 thin films are spin-coated onto rigid or flexible substrates and are shown to quantitatively determine the RH within the range of 0...
July 18, 2018: ACS Applied Materials & Interfaces
Alejandro Silva, Alejandro Zarzo, Juan M Munoz-Guijosa, Francesco Miniello
A common fault in turbomachinery is rotor⁻casing rub. Shaft vibration, measured with proximity probes, is the most powerful indicator of rotor⁻stator rub. However, in machines such as aeroderivative turbines, with increasing industrial relevance in power generation, constructive reasons prevent the use of those sensors, being only acceleration signals at selected casing locations available. This implies several shortcomings in the characterization of the machinery condition, associated with a lower information content about the machine dynamics...
June 13, 2018: Sensors
Jianglin Ye, Huabing Tan, Shuilin Wu, Kun Ni, Fei Pan, Jie Liu, Zhuchen Tao, Yan Qu, Hengxing Ji, Patrice Simon, Yanwu Zhu
High-performance yet flexible micro-supercapacitors (MSCs) hold great promise as miniaturized power sources for increasing demand of integrated electronic devices. Herein, this study demonstrates a scalable fabrication of multilayered graphene-based MSCs (MG-MSCs), by direct laser writing (DLW) of stacked graphene films made from industry-scale chemical vapor deposition (CVD). Combining the dry transfer of multilayered CVD graphene films, DLW allows a highly efficient fabrication of large-areal MSCs with exceptional flexibility, diverse planar geometry, and capability of customer-designed integration...
July 2018: Advanced Materials
Yuxi Zhao, Jeong-Gyu Song, Gyeong Hee Ryu, Kyung Yong Ko, Whang Je Woo, Youngjun Kim, Donghyun Kim, Jun Hyung Lim, Sunhee Lee, Zonghoon Lee, Jusang Park, Hyungjun Kim
The efficient synthesis of two-dimensional molybdenum disulfide (2D MoS2) at low temperatures is essential for use in flexible devices. In this study, 2D MoS2 was grown directly at a low temperature of 200 °C on both hard (SiO2) and soft substrates (polyimide (PI)) using chemical vapor deposition (CVD) with Mo(CO)6 and H2S. We investigated the effect of the growth temperature and Mo concentration on the layered growth by Raman spectroscopy and microscopy. 2D MoS2 was grown by using low Mo concentration at a low temperature...
May 17, 2018: Nanoscale
Zhilong Song, Zhao Huang, Jingyao Liu, Zhixiang Hu, Jianbing Zhang, Guangzu Zhang, Fei Yi, Shenglin Jiang, Jiabiao Lian, Jia Yan, Jianfeng Zang, Huan Liu
Stretchable gas sensors that accommodate the shape and motion characteristics of human body are indispensable to a wearable or attachable smart sensing system. However, these gas sensors usually have poor response and recovery kinetics when operated at room temperature, and especially suffer from humidity interference and mechanical robustness issues. Here, we demonstrate the first fully stretchable gas sensors which are operated at room temperature with enhanced stability against humidity. We created a crumpled quantum dot (QD) sensing layer on elastomeric substrate with flexible graphene as electrodes...
May 25, 2018: ACS Sensors
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