scholarly journals Design and Fabrication of CMOS Microstructures to Locally Synthesize Carbon Nanotubes for Gas Sensing

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4340 ◽  
Author(s):  
Avisek Roy ◽  
Mehdi Azadmehr ◽  
Bao Q. Ta ◽  
Philipp Häfliger ◽  
Knut E. Aasmundtveit
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensing ◽  
Low Cost ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Cmos Process ◽  
Readout Circuits ◽  
Sensing Material ◽  
Bulk Part ◽  
Processing Steps

Carbon nanotubes (CNTs) can be grown locally on custom-designed CMOS microstructures to use them as a sensing material for manufacturing low-cost gas sensors, where CMOS readout circuits are directly integrated. Such a local CNT synthesis process using thermal chemical vapor deposition (CVD) requires temperatures near 900 °C, which is destructive for CMOS circuits. Therefore, it is necessary to ensure a high thermal gradient around the CNT growth structures to maintain CMOS-compatible temperature (below 300 °C) on the bulk part of the chip, where readout circuits are placed. This paper presents several promising designs of CNT growth microstructures and their thermomechanical analyses (by ANSYS Multiphysics software) to check the feasibility of local CNT synthesis in CMOS. Standard CMOS processes have several conductive interconnecting metal and polysilicon layers, both being suitable to serve as microheaters for local resistive heating to achieve the CNT growth temperature. Most of these microheaters need to be partially or fully suspended to produce the required thermal isolation for CMOS compatibility. Necessary CMOS post-processing steps to realize CNT growth structures are discussed. Layout designs of the microstructures, along with some of the microstructures fabricated in a standard AMS 350 nm CMOS process, are also presented in this paper.

Low-Cost Sputtering Process for Carbon Nanotubes Synthesis

2019 ◽  
Vol 891 ◽  
pp. 195-199
Author(s):  
Theerapol Thurakitseree ◽  
Chupong Pakpum
Keyword(s):  
Carbon Nanotubes ◽  
Low Cost ◽  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Synthesis Process ◽  
Metal Thin Films ◽  
Si Substrates ◽  
Custom Made

According to their wonderful properties, carbon nanotubes (CNTs) have been well known for decades. The synthesis process and catalyst deposition method have also drawn attention to control the nanotube structure and properties. Sputtering method is then one promising option to grow the nanotubes in mass production. This method is, however, still costly. Here, we have presented a simple low-cost custom-made DC magnetron sputtering for catalyst thin film deposition. Three different metal thin films (Fe, Ni, Cu) deposited on Si substrates have been employed to investigate nanotube production. Prior to deposition of the catalysts, Al was used as supporting layer. (Al/Fe, Al/Ni, Al/Cu). CNTs were grown by chemical vapor deposition process at 800°C. Ethanol was preliminary used as a carbon source. It was found that CNTs could be successfully grown from only Al/Ni catalysts in our system with the diameter of approximately 200 nm, where the rest of samples were not observed. In addition, vertical-aligned CNTs with the thickness of about 10 μm could be obtained when acetylene was replaced instead of ethanol with reducing partial pressure of the feedstock. A large D-band at 1338 cm-1 with broader G-band at 1582 cm-1 from Raman spectra give a rise to multi layers growth of sp2 carbon walls. Such dimension suggests that it is the characteristic of multi-walled carbon nanotubes.

scholarly journals A Review of Carbon Nanotubes-Based Gas Sensors

2009 ◽  
Vol 2009 ◽  
pp. 1-24 ◽  
Author(s):  
Yun Wang ◽  
John T. W. Yeow
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Low Cost ◽  
High Surface ◽  
Hollow Structure ◽  
Volume Ratio ◽  
Fast Response ◽  
Sensing Technology ◽  
Structure Of Nanomaterials

Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs) has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

Vertically Aligned Carbon Nanotubes from Palm Oil Precursor

2013 ◽  
Vol 667 ◽  
pp. 542-548 ◽  
Author(s):  
A.B. Suriani ◽  
A.A. Azira ◽  
S.F. Nik ◽  
M.H. Taib ◽  
F. Mohamed ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Palm Oil ◽  
Ambient Pressure ◽  
Complex Structure ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Annealing Duration ◽  
Vertically Aligned Carbon Nanotubes ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned

This paper reports a study on vertically aligned carbon nanotubes (VACNTs) synthesized by thermal chemical vapor deposition (TCVD) method using eco-friendly carbon source; palm oil. Palm oil vaporized at 450oC in argon atmosphere at ambient pressure. For better decomposition of palm oil complex structure, ferrocene were added into palm oil and stirred for 20 minutes prior to synthesis process. The synthesis and annealing duration took 30 and 10 minutes respectively. The field emission scanning electron microscopy (FESEM) and infrared spectroscopy analysis were systematically studied on CNTs produced. The detailed of CNTs properties will be discussed further.

Preparation and fluid drag reduction properties of superhydrophobic paper-based films comprising carbon nanotubes and fluoropolymers

2017 ◽  
Vol 24 (2) ◽  
pp. 177-184 ◽  
Author(s):  
Weiwei Ma ◽  
Zhiping Zhou ◽  
Ping Li
Keyword(s):  
Carbon Nanotubes ◽  
Drag Reduction ◽  
Composite Films ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Chemical Vapor Deposition Method ◽  
Fluid Drag ◽  
Acrylate Polymers ◽  
Superhydrophobic Paper ◽  
Fluid Drag Reduction

AbstractCarbon nanotubes (CNTs) were successfully prepared using chemical vapor deposition method on nickel-coated silicon substrates. The CNTs were then modified to obtain functionalized ends. Afterward, acrylate polymers were successfully grafted on the surface of CNTs by atom transfer radical polymerization method. The synthesis process was optimized by studying the surface properties of the composite films. It revealed the existence of chemical bonding between CNTs and polymers. The introduction of CNTs into polymers could improve the water resistance of films. Micro/nano and papillary structures similar to that of lotus leaf were obtained when the polymer matrix was partly etched. The excellent fluid drag reduction performances of film surfaces were expected to be applied in microfluid devices and packaging field.

CNTFET Gas Sensors Using SWCNT Mats: Method for Low-cost Fabrication, Solution to Improve Selectivity, Experimental Results using Interfering Agents

2009 ◽  
Vol 1204 ◽  
Author(s):  
Paolo Bondavalli ◽  
Louis Gorintin ◽  
Pierre Legagneux ◽  
Didier Pribat ◽  
Laurent Caillier ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensors ◽  
Field Effect ◽  
Gas Sensing ◽  
Field Effect Transistors ◽  
Low Cost ◽  
Experimental Results ◽  
Flexible Substrates ◽  
Metal Electrodes ◽  
Sensing Applications

AbstractThe first paper showing the great potentiality of Carbon Nanotubes Field Effect transistors (CNTFETs) for gas sensing applications was published in 2000 [1]. It has been demonstrated that the performances of this kind of sensors are extremely interesting: a sensitivity of around 100ppt (e.g. for NO2 [2]) has been achieved in 2003 and several techniques to improve selectivity have been tested with very promising results [2]. The main issues that have not allowed, up to now, these devices to strike more largely the market of sensors, have been the lack of an industrial method to obtain low-cost devices, a demonstration of their selectivity in relevant environments and finally a deeper study on the effect of humidity and the possible solutions to reduce it. This contribution deals with CNTFETs based sensors fabricated using air-brush technique deposition on large surfaces. Compared to our last contribution [3], we have optimized the air-brush technique in order to obtain high performances transistors (Log(Ion)/Log(Ioff) ∼ 5/6) with highly reproducible characteristics : this is a key point for the industrial exploitation. We have developed a machine which allows us the dynamic deposition on heated substrates of the SWCNT solutions, improving dramatically the uniformity of the SWCNT mats. We have performed tests using different solvents that could be adapted as a function of the substrates (e.g. flexible substrates). Moreover these transistors have been achieved using different metal electrodes (patented approach [4]) in order to improve selectivity. Results of tests using NO2, NH3 with concentrations between ∼ 1ppm and 10ppm will be shown during the meeting.

Numerical Model of Template-Based Chemical Vapor Deposition Processes to Manufacture Carbon Nanotubes for Biological Devices

2015 ◽  
Author(s):  
Yashar Seyed Vahedein ◽  
Michael G. Schrlau
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Process Parameters ◽  
Flow Rate ◽  
Vapor Deposition ◽  
Carbon Nanostructures ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Low Cost ◽  
Chemical Vapor

Carbon nanotubes (CNTs) hold significant promise in the fields of efficient drug delivery and bio-sensing for disease treatment because of their unique properties. In our lab, single and arrayed CNT-tipped devices are manufactured by deposition of carbon on the heated surfaces of templates using chemical vapor deposition (Template-Based Chemical Vapor Deposition, TB-CVD). Experimental results show CNT formation in templates is controlled by TB-CVD process parameters such as flow rate and temperature. However, there is a need for a more comprehensive and low cost way to characterize the flow in the furnace in order to understand how process parameters may affect CNT formation. In this report, 2D and 3D numerical models with Quadrilateral grids were developed using computational fluid dynamic (CFD) commercial codes. Velocity patterns and flow regimes in the tube were compared with experimental data. In addition, statistical techniques were employed to study temperature profiles and velocity patterns in the furnace as a function of flow rate. The outcome of this work will help to elucidate the TB-CVD process and facilitate the efficient manufacture of carbon nanostructures from a variety of templates. The results are broadly applicable to the manufacturing of CNTs and other nanostructured devices used in energy and biomedical fields, including CNT-based devices used in biological applications.

Numerical Investigation of Thermofluid Flow in a Chemical Vapor Deposition Furnace Utilized to Manufacture Template-Synthesized Carbon Nanotubes

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Yashar Seyed Vahedein ◽  
Michael G. Schrlau
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Process Parameters ◽  
Vapor Deposition ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Low Cost ◽  
Chemical Vapor ◽  
Computational Time ◽  
Anodized Aluminum

Template-based chemical vapor deposition (TB-CVD) is a versatile technique for manufacturing carbon nanotubes (CNTs) or CNT-based devices for various applications. In this process, carbon is deposited by thermal decomposition of a carbon-based precursor gas inside the nanoscopic cylindrical pores of anodized aluminum oxide (AAO) templates to form CNTs. Experimental results show that CNT formation in templates is controlled by TB-CVD process parameters, such as time, temperature, and flow rate. However, optimization of this process is done empirically, requiring tremendous time and effort. Moreover, there is a need for a more comprehensive and low cost way to characterize the flow in the furnace in order to understand how process parameters may affect CNT formation. In this report, we describe the development of four, 3D numerical models (73 < Re < 1100), each varying in complexity, to elucidate the thermofluid behavior in the TB-CVD process. Using computational fluid dynamic (CFD) commercial codes, the four models are compared to determine how the presence of the template and boat, composition of the precursor gas, and consumption of species at the template surface affect the temperature profiles, velocity fields, mixed convection, and strength of circulations in the system. The benefits and shortcomings of each model, as well as a comparison of model accuracy and computational time, are presented. Due to limited data, simulation results are validated by experiments and visual observations of the flow structure whenever possible. Decent agreement between experimental data and simulation supports the reliability of the simulation.

scholarly journals Gas sensing with gold-decorated vertically aligned carbon nanotubes

2014 ◽  
Vol 5 ◽  
pp. 910-918 ◽  
Author(s):  
Prasantha R Mudimela ◽  
Mattia Scardamaglia ◽  
Oriol González-León ◽  
Nicolas Reckinger ◽  
Rony Snyders ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Gold Nanoparticles ◽  
Nitrogen Dioxide ◽  
Room Temperature ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Vertically Aligned Carbon Nanotubes ◽  
Aligned Carbon Nanotubes ◽  
Vertically Aligned ◽  
Carbon Nanotube Forests

Vertically aligned carbon nanotubes of different lengths (150, 300, 500 µm) synthesized by thermal chemical vapor deposition and decorated with gold nanoparticles were investigated as gas sensitive materials for detecting nitrogen dioxide (NO2) at room temperature. Gold nanoparticles of about 6 nm in diameter were sputtered on the top surface of the carbon nanotube forests to enhance the sensitivity to the pollutant gas. We showed that the sensing response to nitrogen dioxide depends on the nanotube length. The optimum was found to be 300 µm for getting the higher response. When the background humidity level was changed from dry to 50% relative humidity, an increase in the response to NO2 was observed for all the sensors, regardless of the nanotube length.

scholarly journals Carbon nanotubes synthesis using carbonization of pretreated rice straw through chemical vapor deposition of camphor

RSC Advances ◽  
2017 ◽  
Vol 7 (45) ◽  
pp. 28535-28541 ◽  
Author(s):  
Nady A. Fathy
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Rice Straw ◽  
Vapor Deposition ◽  
Low Cost ◽  
Chemical Vapor ◽  
Catalyst Supports ◽  
Renewable Biomass ◽  
Biomass Resources

There is a pressing demand to prepare low-cost carbon nanotubes (CNTs) from renewable biomass resources as cheap carbon precursors and catalyst supports during chemical vapor deposition (CVD).

FLOATING CATALYST CVD SYNTHESIS OF CARBON NANOTUBES USING IRON (III) CHLORIDE: INFLUENCES OF THE GROWTH PARAMETERS

NANO ◽  
2009 ◽  
Vol 04 (06) ◽  
pp. 359-366 ◽  
Author(s):  
MEHRNOUSH KHAVARIAN ◽  
SIANG-PIAO CHAI ◽  
SOON HUAT TAN ◽  
ABDUL RAHMAN MOHAMED
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Reaction Temperature ◽  
Growth Parameters ◽  
Low Cost ◽  
Chemical Vapor ◽  
Flow Ratio ◽  
Transmission Electron ◽  
High Efficient ◽  
Synthesis Of Carbon Nanotubes

Carbon nanotubes (CNTs) were synthesized by a low-cost floating catalyst (FC) chemical vapor deposition (CVD) method in a horizontal reactor. It was found that iron (III) chloride ( FeCl3 ) is a high efficient FC precursor for methane CVD to grow CNTs. In this study, the effects of reaction temperature and flow ratio of methane to nitrogen ( CH4:N2 ) on the morphology of the CNTs were investigated. The morphological analysis by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that increasing the reaction temperature and flow ratio of CH4:N2 grew CNTs of larger diameters. Energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA) were employed to study the purity of the produced CNTs. As shown by the TGA, the highest yield of 74.19% was recorded for the CNTs grown at 1000°C and flow ratio CH4:N2 of 300:200.

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