Title: Nanopore-based Nanofluidic Transistors: Simulation, Fabrication and Measurements of Gate-Equipped Nanopores (Nanofluïdische transistoren gebaseerd op nanoporiën: Het simuleren, maken en uitmeten van nanoporiën uitgerust met een gate-elektrode)
Other Titles: Nanopore-based Nanofluidic Transistors: Simulation, Fabrication and Measurements of Gate-Equipped Nanopores
Authors: Kox, Ronald; M0116622
Issue Date: 15-Mar-2011
Abstract: The continuous trend of downscaling in fields like electronics and mechanics during the past decades have led to countless technological advancements that influence us every day. Driven in no small part by Moore's law, scientists have worked fiercely to create increasingly small features, and this has had an impact far beyond the field of micro- and nano-electronics. With functional components approaching the size of individual biomolecules, new possibilities arise in the field of biosensing, and single molecule detection and manipulation has come within our grasp.The research presented here is situated in the field of nanofluidics, which is a result of the downscaling trend in fluidics and microfluidics. When fluidic channels approach nanoscale dimensions and their surface-to-volume ratio becomes increasingly large, surface charges on the channel walls start playing an important role, and a number of interesting new effects come into play. The most prominent ones are exclusionenrichment and concentration polarization, which have applications such as biosensing, filtering, preconcentration and desalination. With regard to biomolecular research, the field of nanofluidics has seen two distinct movements, each with a different goal. On the one hand, there is nanopore research, which is directly aimed at the detection and analysis of biomolecules like proteins and nucleic acids, and ultimately seeks to provide an alternative, amplification free method for DNA sequencing. On the other hand, there are nanofluidic transistors, which are directly aimed at control of the transport properties of nanofluidic channels and the electrostatic manipulation of ions and other charged particles and biomolecules.This work seeks to combine these two movements through the study of nanopore-based nanofluidic transistors, or nanopore transistors in short, which have the potential of combining biosensing and biomanipulation into a single device. This dissertation starts with a theoretical study of nanofluidics, and discusses some models that can provide insight into the phenomena that occur around the nanopore or can be used to fit experimental data. The main part of this work focuses on the fabrication of nanopores, which form the core of any nanopore transistor, and will give a detailed discussion of the fabrication process. To further fine-tune the fabricated nanopores, a technique called electron-beam induced deposition (EBID) is introduced, which can be used to change the size and surface properties of existing nanopores, or to select a nanopore from an array. The experimental section of this work shows some nanopore measurement results, and focuses on investigating the surface charges of the nanopores, but also shows some DNA and nanoparticle measurements. The final part of this work shows the first nanopore transistor results, and shows the possibility of electrostatically tuning the ionic current through a nanopore and some possible ways to further improve the operation of the fabricated devices.
Table of Contents: 1 Introduction 1
2 Nanofluidic Theory and Modeling 7
2.1 Introduction to nanofluidics 7
2.2 An overview of nanofluidic models 21
2.3 Implementing a 2D model 25
2.4 Implementing an analytical model 30
2.5 Conclusion 33
3 Fabricating Nanopores 35
3.1 Introduction to nanopore fabrication techniques 35
3.2 Making nanopores using anisotropic etching 43
3.3 Making a freestanding membrane 59
3.4 Toward the full wafer processing of nanopores 63
3.5 Conclusion 68
4 Shrinking nanopores using electron-beam induced deposition 71
4.1 Introduction to electron-beam induced deposition 71
4.2 Shrinking nanopores using carbon contamination 74
4.3 Shrinking using EBID with different precursors 80
4.4 Conclusion 83
5 Measuring Nanopores 85
5.1 Introduction to nanopore measurements 86
5.2 Building a measurement setup 93
5.3 Analysing nanopore surface charges 96
5.4 Measuring translocations 102
5.5 Conclusion 103
6 Nanopore-based nanofluidic transistors 105
6.1 Introduction to biomimetic nanopores 105
6.2 Making a nanopore-based nanofluidic transistor 110
6.3 Measuring nanofluidic transistors 113
6.4 Conclusion 119
7 General Conclusion and Outlook 121
7.1 Theoretical study 121
7.2 Fabrication 122
7.3 Characterization 123
7.4 Discussion and outlook 123
A Comparing nanofluidics and semiconductor physics 127
B KOH Etch Rates 129
C Evaluating possible KOH masking layers 131
D List of publications 134
E Curriculum Vitae 136
Bibliography 137
Publication status: published
KU Leuven publication type: TH
Appears in Collections:Electrical Engineering - miscellaneous
Associated Section of ESAT - INSYS, Integrated Systems
Physics and Astronomy - miscellaneous
Semiconductor Physics Section

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