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Flexible gas sensor

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 (ppm)-level breath ammonia is a medical biomarker for kidney disorders and Helicobacter pylori (H. pylori) bacteria-induced stomach infections. The humidity varies both in 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 nano-scale moisture-blocking CeO2 overlayer by electron-beam evaporation...
July 27, 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%...
July 26, 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
Xu Zhou, Kaifeng Niu, Zi Wang, Lizhen Huang, Lifeng Chi
Organic thin film transistor (OTFT) based gas sensors have demonstrated promising applications, owing to their advantages of high selectivity and room temperature operation, accompanied by their low cost, large scale manufacture, and flexibility. However, the understanding of the sensing mechanism is far from clear. Herein, we reveal the sensing mechanism of an organic transistor sensor for ammonia (NH3) detection through studying the recovery behavior in various atmospheres. Inspired by the significant difference in the recovery of the transistor sensor in N2 and in air, we deduced that the operation mechanism should not only involve the NH3-film interaction...
May 10, 2018: Nanoscale
Yifan Li, Meng Su, Zheng Li, Zhandong Huang, Fengyu Li, Qi Pan, Wanjie Ren, Xiaotian Hu, Yanlin Song
The precise integration of microscale dots and lines with controllable interfacing connections is highly important for the fabrication of functional devices. To date, the solution-processible methods are used to fabricate the heterogeneous micropatterns for different materials. However, for increasingly miniaturized and multifunctional devices, it is extremely challenging to engineer the uncertain kinetics of a solution on the microstructures surfaces, resulting in uncontrollable interface connections and poor device performance...
May 2018: Small
Qiankun Zhang, Chunhua An, Shuangqing Fan, Sigang Shi, Rongjie Zhang, Jing Zhang, Quanning Li, Daihua Zhang, Xiaodong Hu, Jing Liu
Minimizing the strain-induced undesirable effects is one of the major efforts to be made for flexible electronics. This work demonstrates a highly sensitive flexible gas sensor with ultra-low strain response, which is potentially suitable for wearable electronics applications. The gas sensing material is a free-standing and flexible thin film made of graphene/ethyl cellulose (EC) nanocomposite, which is then integrated with flexible substrate of polyethylene terephthalate. The sensor exhibits relative resistance change within 0...
July 13, 2018: Nanotechnology
Yuxiang Qin, Liping Wang, Xiaofei Wang
Layered double hydroxides (LDHs) have recently been revealed to be promising in gas sensor applications due to their compositional flexibility and unique 2D-interlayer channel for gas diffusion and adsorption. This work demonstrates highly porous hierarchical LDHs containing Mg2+ and Al3+ (MgAl-LDHs) for ethanol sensing at room temperature. These MgAl-LDHs, with unique flower-like hierarchical structure and mesoporous interlayer, were synthesized hydrothermally using sodium dodecyl sulfate as soft template as well as intercalating agent...
July 6, 2018: Nanotechnology
Yunnan Fang, Mitra Akbari, Jimmy G D Hester, Lauri Sydänheimo, Leena Ukkonen, Manos M Tentzeris
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
April 16, 2018: Scientific Reports
João Flavio da Silveira Petruci, Andreas Wilk, Arnaldo Alves Cardoso, Boris Mizaikoff
Following the Kyoto protocol, all signatory countries must provide an annual inventory of greenhouse-gas emission including N2 O. This fact associated with the wide variety of sources for N2 O emissions requires appropriate sensor technologies facilitating in-situ monitoring, compact dimensions, ease of operation, and sufficient sensitivity for addressing such emission scenarios. In this contribution, we therefore describe an innovative portable mid-infrared chemical sensor system for quantifying gaseous N2 O via coupling a substrate-integrated hollow waveguide (iHWG) simultaneously serving as highly miniaturized mid-infrared photon conduit and gas cell to a custom-made preconcentrator...
April 12, 2018: Scientific Reports
Youngoh Lee, Jonghwa Park, Soowon Cho, Young-Eun Shin, Hochan Lee, Jinyoung Kim, Jinyoung Myoung, Seungse Cho, Saewon Kang, Chunggi Baig, Hyunhyub Ko
Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47...
April 24, 2018: ACS Nano
Xiaojiang Liu, Hongcheng Gu, Min Wang, Xin Du, Bingbing Gao, Abdelrahman Elbaz, Liangdong Sun, Julong Liao, Pengfeng Xiao, Zhongze Gu
Bioinspired re-entrant structures have been proved to be effective in achieving liquid superrepellence (including anti-penetration, anti-adhesion, and anti-spreading). However, except for a few reports relying on isotropic etching of silicon wafers, most fluorination-dependent surfaces are still unable to repel liquids with extreme low surface energy (i.e., γ < 15 mN m-1 ), especially those fluorinated solvents. Herein, triply re-entrant structures, possessing superrepellence to water (with surface tension γ of 72...
May 2018: Advanced Materials
Miriam Alvarado, Èric Navarrete, Alfonso Romero, José Luis Ramírez, Eduard Llobet
Indium oxide octahedral nanopowders were obtained from an ionic precursor compound after an oxidation process conducted under a low-oxygen atmosphere. This method was found to produce contamination-free indium oxide nanomaterial with very similar morphological and crystalline properties to the one produced by vapor-phase transport, but at significantly lower temperatures and higher yield. The as-synthesized indium oxide was mixed to an organic vehicle and microdrop deposited to form a film bridging the interdigitated silver electrodes patterned on top of a flexible, polyimide (Kapton&reg; ), substrate...
March 28, 2018: Sensors
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