A highly sensitive gas-sensing platform based on a metal-oxide nanowire forest grown on a suspended carbon nanowire fabricated at a wafer level

Lim, Yeongjin; Kim, Soosung; Kwon, Yeo‐Jung; Baik, Jeong Min; Shin, Heungjoo

doi:10.1016/j.snb.2017.12.167

Cited by 27 publications

(10 citation statements)

References 43 publications

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“…Contrary to our methodology, other available technologies that integrate carbon nanowires into C-MEMS structures conventionally require a two-step process consisting of (1) the fabrication of the micron-ranged supporting structures (usually through UV-photolithography) and (2) the fabrication of the carbon nanowire precursor, for example through two-step photolithography 58 , far field electrospinning 29,55 , or electromechanical spinning 40 . Leveraging the fabrication advantages of TPP, however, comes with added fabrication complexity, in terms of required equipment and operating conditions (i.e., a stable femtosecond pulsed laser).…”

Section: Discussionmentioning

confidence: 99%

Pyrolysis-induced shrinking of three-dimensional structures fabricated by two-photon polymerization: experiment and theoretical model

et al. 2019

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The introduction of two-photon polymerization (TPP) into the area of Carbon Micro Electromechanical Systems (C-MEMS) has enabled the fabrication of three-dimensional glassy carbon nanostructures with geometries previously unattainable through conventional UV lithography. Pyrolysis of TPP structures conveys a characteristic reduction of feature size—one that should be properly estimated in order to produce carbon microdevices with accuracy. In this work, we studied the volumetric shrinkage of TPP-derived microwires upon pyrolysis at 900 °C. Through this process, photoresist microwires thermally decompose and shrink by as much as 75%, resulting in glassy carbon nanowires with linewidths between 300 and 550 nm. Even after the thermal decomposition induced by the pyrolysis step, the linewidth of the carbon nanowires was found to be dependent on the TPP exposure parameters. We have also found that the thermal stress induced during the pyrolysis step not only results in axial elongation of the nanowires, but also in buckling in the case of slender carbon nanowires (for aspect ratios greater than 30). Furthermore, we show that the calculated residual mass fraction that remains after pyrolysis depends on the characteristic dimensions of the photoresist microwires, a trend that is consistent with several works found in the literature. This phenomenon is explained through a semi-empirical model that estimates the feature size of the carbon structures, serving as a simple guideline for shrinkage evaluation in other designs.

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Section: Discussionmentioning

confidence: 99%

Pyrolysis-induced shrinking of three-dimensional structures fabricated by two-photon polymerization: experiment and theoretical model

et al. 2019

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“…ZnO NWs have also been utilized for NO 2 sensing applications [126][127][128]. Ahn et al proposed the synthesis of bridged vertically oriented ZnO NWs on a SiO 2 /Si/Ti/Pt substrate for NO 2 sensing [129].…”

Section: No 2 Sensorsmentioning

confidence: 99%

Recent progress and perspectives of gas sensors based on vertically oriented ZnO nanomaterials

Ahmad

Majhi

Zhang

et al. 2019

Advances in Colloid and Interface Science

149

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Vertically oriented zinc oxide (ZnO) nanomaterials, such as nanorods (NRs), nanowires (NWs), nanotubes (NTs), nanoneedles (NNs), and nanosheets (NSs), are highly ordered architectures that provide remarkable properties for sensors. Furthermore, these nanostructures have fascinating features, including high surface-area-to-volume ratios, high charge carrier concentrations, and many surface-active sites. These features make vertically oriented ZnO nanomaterials exciting candidates for gas sensor fabrication. The development of efficient methods for the production of vertically oriented nanomaterial electrode surfaces has resulted in improved stability, high reproducibility, and gas sensing performance. Moving beyond conventional fabrication processes that include binders and nanomaterial deposition steps has been crucial, as the materials from these processes suffer from poor stability, low reproducibility, and marginal sensing performance. In this feature article, we comprehensively describe vertically oriented ZnO nanomaterials for gas sensing applications. The uses of such nanomaterials for gas sensor fabrication are discussed in the context of ease of growth, stability on an electrode surface, growth reproducibility, and enhancements in device efficiency as a result of their unique and advantageous features. In addition, we summarize applications of gas sensors for a variety of toxic and volatile organic compound (VOC) gases, and we discuss future directions of the vertically oriented ZnO nanomaterials.

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“…The MEMS sensor exhibited gas responses of 8.1, 7.2, and 10.0% for CO, SO 2 , and C 6 H 6 at 10 ppm, respectively, as shown in Figure 12 . The detailed sensor performances and characteristics of the suspended sensor architecture of the MEMS sensor were reported elsewhere [ 21 ]. The resistance change of the gas sensor was measured in the range of 30 kΩ–70 kΩ with changes in the concentration of CO, SO 2 , and C 6 H 6 gas between 0.5 ppm and 1000 ppm, respectively.…”

Section: Measurement Resultsmentioning

confidence: 99%

“…The suspended carbon nanowire and supporting carbon posts were fabricated monolithically using carbon microelectromechanical systems (MEMS) technology that enables wafer-level carbon nanostructure fabrication using photolithography and pyrolysis [ 19 ]. Owing to good mechanical robustness, the suspended carbon nanowire can be selectively coated with gas sensing materials such as Pd nanoparticles and metal-oxide nanowires using electrode position and hydrothermal growth, respectively [ 20 , 21 ]. High aspect ratio and large surface to volume ratio of the suspended wire enables highly sensitive gas sensing.…”

Section: Wireless Multi-gas Sensor Interfacementioning

confidence: 99%

A Three-Step Resolution-Reconfigurable Hazardous Multi-Gas Sensor Interface for Wireless Air-Quality Monitoring Applications

Choi

Park

Lee

et al. 2018

Sensors

Self Cite

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This paper presents a resolution-reconfigurable wide-range resistive sensor readout interface for wireless multi-gas monitoring applications that displays results on a smartphone. Three types of sensing resolutions were selected to minimize processing power consumption, and a dual-mode front-end structure was proposed to support the detection of a variety of hazardous gases with wide range of characteristic resistance. The readout integrated circuit (ROIC) was fabricated in a 0.18 μm CMOS process to provide three reconfigurable data conversions that correspond to a low-power resistance-to-digital converter (RDC), a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC), and a 16-bit delta-sigma modulator. For functional feasibility, a wireless sensor system prototype that included in-house microelectromechanical (MEMS) sensing devices and commercial device products was manufactured and experimentally verified to detect a variety of hazardous gases.

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A highly sensitive gas-sensing platform based on a metal-oxide nanowire forest grown on a suspended carbon nanowire fabricated at a wafer level

Cited by 27 publications

References 43 publications

Pyrolysis-induced shrinking of three-dimensional structures fabricated by two-photon polymerization: experiment and theoretical model

Pyrolysis-induced shrinking of three-dimensional structures fabricated by two-photon polymerization: experiment and theoretical model

Recent progress and perspectives of gas sensors based on vertically oriented ZnO nanomaterials

A Three-Step Resolution-Reconfigurable Hazardous Multi-Gas Sensor Interface for Wireless Air-Quality Monitoring Applications

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