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Electrochemically-Grown Single Nanowire Array for Highly Sensitive and Selective Chemical Detection

Hu, Yushi (2011) Electrochemically-Grown Single Nanowire Array for Highly Sensitive and Selective Chemical Detection. Doctoral Dissertation, University of Pittsburgh.

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    Abstract

    One dimensional nanostructures (nanowires) have emerged as important building blocks for micro/nano devices, such as chemical and biomolecular sensors, photovoltaic devices, nonvolatile memories, and nano power generators. In this work, the fabrication and characterization of single metal, conducting polymer and metal oxide nanowires will be discussed. These single nanowires were synthesized site-specifically inside Polymethyl methacrylate (PMMA) channels defined by electron beam lithography (EBL) via electrochemical deposition. The dimensions of these nanowires were predefined by optical lithography and EBL, and the widths were from 100 nm to 50 nm and the lengths were from 3 to 7 microns. A gate-assisted electrochemical deposition method that was able to effectively improve the nanowire growth will be discussed. The successful integration of four different single nanowires on a single chip will also be demonstrated.The applications of these single nanowires will be presented. A highly sensitive hydrogen sensor with fast response (<20 s) and extremely low detection limit (2 ppm) was achieved using single Palladium (Pd) nanowire. The structure of the Pd nanowire was found to be closely related to the growth condition, and different sensing mechanisms were discovered for different nanowire structures.An electronic nose was built on a single chip using a nanowire array consisting of four different single nanowires, including Pd, Polypyrrole (PPy), Polyaniline (PANI), and ZnO nanowires. The sensing performances of this electronic nose for four different target gases, including carbon monoxide (CO), hydrogen (H2), nitrogen dioxide (NO2), and methanol (CH3OH), were studied in detail. Principal Component Analysis (PCA) was employed to analyze the sensing signals and each target gas was clearly identified. A blind test was conducted to verify the performance of this e-nose.


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    Details

    Item Type: University of Pittsburgh ETD
    Creators/Authors:
    CreatorsEmailORCID
    Hu, Yushihu.yushi@gmail.com
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairYun, Minheeyunmh@engr.pitt.edu
    Committee MemberFalk, JoelFalk@engr.pitt.edu
    Committee MemberChen, Kevinkchen@engr.pitt.edu
    Committee MemberCho, Sung Kwonskc@engr.pitt.edu
    Committee MemberStanchina, Williamwstanchina@engr.pitt.edu
    Title: Electrochemically-Grown Single Nanowire Array for Highly Sensitive and Selective Chemical Detection
    Status: Unpublished
    Abstract: One dimensional nanostructures (nanowires) have emerged as important building blocks for micro/nano devices, such as chemical and biomolecular sensors, photovoltaic devices, nonvolatile memories, and nano power generators. In this work, the fabrication and characterization of single metal, conducting polymer and metal oxide nanowires will be discussed. These single nanowires were synthesized site-specifically inside Polymethyl methacrylate (PMMA) channels defined by electron beam lithography (EBL) via electrochemical deposition. The dimensions of these nanowires were predefined by optical lithography and EBL, and the widths were from 100 nm to 50 nm and the lengths were from 3 to 7 microns. A gate-assisted electrochemical deposition method that was able to effectively improve the nanowire growth will be discussed. The successful integration of four different single nanowires on a single chip will also be demonstrated.The applications of these single nanowires will be presented. A highly sensitive hydrogen sensor with fast response (<20 s) and extremely low detection limit (2 ppm) was achieved using single Palladium (Pd) nanowire. The structure of the Pd nanowire was found to be closely related to the growth condition, and different sensing mechanisms were discovered for different nanowire structures.An electronic nose was built on a single chip using a nanowire array consisting of four different single nanowires, including Pd, Polypyrrole (PPy), Polyaniline (PANI), and ZnO nanowires. The sensing performances of this electronic nose for four different target gases, including carbon monoxide (CO), hydrogen (H2), nitrogen dioxide (NO2), and methanol (CH3OH), were studied in detail. Principal Component Analysis (PCA) was employed to analyze the sensing signals and each target gas was clearly identified. A blind test was conducted to verify the performance of this e-nose.
    Date: 19 September 2011
    Date Type: Completion
    Defense Date: 07 June 2011
    Approval Date: 19 September 2011
    Submission Date: 09 June 2011
    Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Doctoral Dissertation
    Refereed: Yes
    Degree: PhD - Doctor of Philosophy
    URN: etd-06092011-161118
    Uncontrolled Keywords: chemical sensor; Electrochemical deposition; electronic nose; nanowire
    Schools and Programs: Swanson School of Engineering > Electrical Engineering
    Date Deposited: 10 Nov 2011 14:46
    Last Modified: 10 Feb 2012 09:57
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-06092011-161118/, etd-06092011-161118

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