Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


41559.pdf (13.3 MB)

ETD Abstract Container

Abstract Header

Deep subthreshold Schottky regime based amorphous oxide semiconductor TFTs for sensitive detection of neurotransmitters

Barua, Abhijeet
http://orcid.org/0000-0003-0180-9306
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1636028763021019

Abstract Details

2021, PhD, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
To understand synaptic plasticity, it is vital to delve into the foundational mechanism that drives such phenomena. Fundamentally, synaptic transmission depends on the alteration of neurochemical receptors, the quantity of such neurotransmitters, postsynaptic Ca2+ release, postsynaptic neuronal responses to active secretion/reuptake, and modulation of excitatory or inhibitory behavior. It is crucial to isolate and decipher each basis above for complex behavioral analysis in an individual. Overall, an in vitro implementation was attempted here for the detection of synthetic Dopamine neurotransmitter in a purely electronic manner through AOS TFTs. This provides a base for future in vivo lab-to-patient adaptations of such a platform. For this purpose, initially, non-passivated binary ZnO TFTs were developed through a physical sputter deposition and wet etch process, and their pristine electrical behavior was analyzed. Previously designed and optimized Tobramycin ssDNA aptamers were surface tethered and anchored to ZnO channel substrates through crosslinker immobilization chemistry. Such biosensors were used to detect small-molecule Tobramycin in a low dynamic range of 1nM-100nM concentration with a saturated maximum current change of ˜0.667nA and aptamer-target dissociation constant of ˜0.534×10-9mol/liter or M as a proof-of-concept study with previously standardized Tobramycin target. The complications that were encountered with ZnO motivated the exploration of other compound material systems and immobilization chemistries. From multiple iterations and preliminary data, the quaternary compound semiconductor IGZO was selected as the channel layer. Altogether, a low-thermal budget combination of physical sputter/PLD and chemical ALD deposition was used with a wet etch process to pattern Schottky source/drain contacts over the non-passivated channel. As anticipated, in deep subthreshold electrical analysis, these short channel devices exhibited high r0 =1012Ω and Ai =100 when operated in the ultralow power unity voltage range. Dry state PBS and stability studies confirmed the robustness and limited voltage drift of this regime with a subthreshold voltage drift of only ˜0.0582V with a trap time of ˜408μs. This inspired the operation of long channel TFTs in the unity voltage region with groundwork for gate/drain bias selection in biosensor applications. Dry state intrinsic signal gain was as high as Ai ˜1000 in the Schottky based deep subthreshold regime under unity voltage operation. Simultaneous examination of immobilization chemistry led to the selection of an alkyne-azide “click” chemistry which anchored Dopamine-specific ssDNA receptors to non-passivated IGZO surface for sensitive and selective detection of Dopamine. Multiple reagents, cross-linker, heat, and cure steps were precluded by such a selection and a catalytic attachment of alkyne-terminated silane to azide-anchored aptamer was realized. Biosensor calibration response curves were extracted for determination of lower limit of detection between 1nM-100pM and selective (complementary) recognition against previously described Tobramycin as an interferant. Finally, SiO2 passivated channels were implemented to understand the evolution of biosensor behavior under prolonged solution environments through repeated sensitive and selective detection of Dopamine against ATP after comprehensive pristine state characterization. Cyclic drift and regeneration studies were performed on aptamer immobilized devices through a 34-day period. The calibrated response profiles extracted against buffer solution baselines before and after the regeneration period were shifted.
Rashmi Jha, Ph.D. (Committee Chair)
Vidya Chidambaran (Committee Member)
Ryan White (Committee Member)
Tao Li, Ph.D. (Committee Member)
Kevin Leedy, Ph.D. (Committee Member)
263 p.
Electrical Engineering
Thin Film Transistor; InGaZnO; Biosensor; Aptamer; Detection; Regeneration

Recommended Citations

Citations

  • Barua, A. (2021). Deep subthreshold Schottky regime based amorphous oxide semiconductor TFTs for sensitive detection of neurotransmitters [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1636028763021019

    APA Style (7th edition)

  • Barua, Abhijeet. Deep subthreshold Schottky regime based amorphous oxide semiconductor TFTs for sensitive detection of neurotransmitters. 2021. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1636028763021019.

    MLA Style (8th edition)

  • Barua, Abhijeet. "Deep subthreshold Schottky regime based amorphous oxide semiconductor TFTs for sensitive detection of neurotransmitters." Doctoral dissertation, University of Cincinnati, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1636028763021019

    Chicago Manual of Style (17th edition)

ucin1636028763021019
259
© 2021, some rights reserved.Creative Commons License Deep subthreshold Schottky regime based amorphous oxide semiconductor TFTs for sensitive detection of neurotransmitters by Abhijeet Barua is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.