Liu, Pei
(2018)
TWO-DIMENSIONAL POLYANILINE NANOSTRUCTURES FOR THE DEVELOPMENT OF ULTRASENSITIVE FLEXIBLE BIOSENSORS.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The demand for ultrasensitive, inexpensive and wearable biosensors is always strong due to the increasing healthcare related concerns. In this work, field-effect-transistor (FET) biosensors based on two-dimensional (2-D) polyaniline (PANI) nanostructures were developed on both nonflexible (SiO2) and flexible substrates (polyethylene terephthalate and polyimide). The biosensor devices were fabricated through a facile and inexpensive method that combines top-down and bottom-up processes. A low-temperature bilayer process was developed that vastly improved the yield of flexible devices. The chemically synthesized PANI nanostructures showed excellent p-type semiconductor properties as well as good compatibility with flexible designs. With the 2-D PANI nanostructure being as thin as 80 nm and its extremely large surface-area-to-volume (SA/V) ratio due to the intrinsic properties of PANI chemical synthesis, the developed biosensors exhibited outstanding sensing performance in detecting B-type natriuretic peptide (BNP) biomarkers. Excellent reproducibility, and high specificity with the limit of detection as low as 100 pg/mL were achieved for both designs. PANI nanostructure under bending condition was also investigated and showed controllable conductance changes being less than 20% with good restorability which may open up the possibility for wearable applications.
In addition, a facile and template-free method is demonstrated to synthesize a new two-dimensional thin film structure: PANI film/nanotubes hybrid. The hybrid is a 100 nm thick PANI film embedded with PANI nanotubes. This well controlled method requires no surfactant or organic acid as well as relatively low concentration of reagents. Synthesis condition studies reveal that aniline oligomers with certain structures are responsible for guiding the growth of the nanotubes. Electrical characterization also indicates that the hybrid nanostructure possesses similar FET characteristics to bare PANI film. With its 20% increased SA/V ratio contributed by surface embedded nanotubes and the excellent p-type semiconducting characteristic, PANI film/nanotubes hybrid shows clear superiority compared with bare PANI film. Such advantages guarantee the hybrid a promising future towards the development of ultra-high sensitivity and low cost biosensors.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
25 January 2018 |
| Date Type: |
Publication |
| Defense Date: |
10 July 2017 |
| Approval Date: |
25 January 2018 |
| Submission Date: |
14 September 2017 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
118 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Electrical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Biosensor; Polyaniline; Flexible; nanotube; 2-D nanostru |
| Date Deposited: |
25 Jan 2018 21:39 |
| Last Modified: |
25 Jan 2018 21:39 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/33197 |
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