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Self-Assembled Carbon Nanotube as an Optical Immunosensor for Point-of-Care Clinical Diagnostics

Shim, Joon Sub
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282931376

Abstract Details

2010, PhD, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
In this research, a new method for the self-assembly of carbon nanotubes (CNTs) using magnetic capturing and fluidic alignment has been developed and characterized. In this new method, the residual iron (Fe) catalyst at one end of the CNT was utilized as a self-assembly driver to attract and locate the CNT using magnetic forces, while the assembled CNT was aligned by the shear force induced from the fluid flow through the assembly channel. The self-assembly principles and procedures were successfully developed and the electrical properties of the assembled multi-walled carbon nanotube (MWNT) and single-walled carbon nanotube (SWNT) were fully characterized. The new assembly method developed in this work shows its feasibility for the precise self-assembly of parallel CNTs for electronic devices and nano-biosensors. In order to prepare the electrodes for the assembly of CNTs, a self-aligned nano-scale gap between multiple metal layers has been fabricated using a technique of controlled undercut and metallization and has been applied to the massive assembly of the individual CNT. The new method enables conventional optical lithography to fabricate nanogap electrodes and self-aligned patterns with nano-scale precision. The self-aligned Ni pattern on the nanogap electrode provides an assembly spot where the residual Fe catalyst at the end of the CNT is magnetically captured. The captured CNT is aligned parallel to the flow direction by fluidic shear force. The combined forces of magnetic attraction and fluidic alignment achieve the massive self-assembly of CNTs at target positions. Single walled nanotubes (SWNTs) were successfully assembled between the nanogap electrodes and their electrical responses were fully characterized, showing stable current-voltage (I-V) responses. As an application of the CNT-assembled electrode to a functional device, an on-chip optical immunosensor using CNTs with a photovoltaic polymer coating has been proposed, developed, characterized and applied for the detection of a cardiac biomarker in this work. An individual CNT was assembled on a titanium (Ti) electrode and coated with a photovoltaic polymer, and then insulated with Parylene. Under an incident light, the photovoltaic polymer generated electrons that changed the conductivity of the CNT. The on-chip chemiluminescent immunoassay was directly performed on the CNT photodetector for the detection of Cardiac Troponin T (cTnT) with a concentration of 12 pg/ml, which envisaged a new optical immunosensor using the self-assembled CNT for point-of-care (POC) clinical diagnostics. In conclusion, a new self-assembly of CNTs using magnetic capturing and fluidic alignment has been designed, developed and characterized in this work for addressing the difficulty of CNT assembly at the target position between two electrodes with a nanogap. The electrodes with a nanogap were also newly developed using a technique of controlled undercut and metallization and then fully characterized as assembly beds for the self-assembled CNT. Finally, the new assembly methods and devices have been successfully applied to the new optical immunosensor with high sensitivity for POC clinical diagnostics.
Chong Ahn, PhD (Committee Chair)
Vesselin Shanov, PhD (Committee Member)
Marc Cahay, PhD (Committee Member)
Mark Schulz, PhD (Committee Member)
Jason Heikenfeld, PhD (Committee Member)
129 p.
Electrical Engineering
Carbon Nanotube; CNT Biosensor; Self Assembly; Point-of-Care Testing; Lab-on-a-Chip; Nano Biosensor

Recommended Citations

Citations

  • Shim, J. S. (2010). Self-Assembled Carbon Nanotube as an Optical Immunosensor for Point-of-Care Clinical Diagnostics [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282931376

    APA Style (7th edition)

  • Shim, Joon Sub. Self-Assembled Carbon Nanotube as an Optical Immunosensor for Point-of-Care Clinical Diagnostics. 2010. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282931376.

    MLA Style (8th edition)

  • Shim, Joon Sub. "Self-Assembled Carbon Nanotube as an Optical Immunosensor for Point-of-Care Clinical Diagnostics." Doctoral dissertation, University of Cincinnati, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282931376

    Chicago Manual of Style (17th edition)

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© 2010, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.