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- Li, Shiyu, 1991-
(författare)
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Engineering Surfaces of Solid-State Nanopores for Biomolecule Sensing
- 2021
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- Nanopores have emerged as a special class of single-molecule analytical tool that offers immense potential for sensing and characterizing biomolecules such as nucleic acids and proteins. As an alternative to biological nanopores, solid-state nanopores present remarkable versatility due to their wide-range tunability in pore geometry and dimension as well as their excellent mechanical robustness and stability. However, being intrinsically incompatible with biomolecules, surfaces of inorganic solids need be modified to provide desired functionalities for real-life sensing purposes. In this thesis, we presented an exploration of various surface engineering strategies and an examination of several surface associated phenomena pertaining specifically to solid-state nanopores. Based on the parallel sensing concept using arrayed pores, optical readout is mainly employed throughout the whole study.For the surface engineering aspect, a list of approaches was explored. A versatile surface patterning strategy for immobilization of biomolecules was developed based on selective poly(vinylphosphonic acid) passivation and electron beam induced deposition technique. This scheme was then implemented on nanopore arrays for nanoparticle localization. In addition, vesicle rupture-based lipid bilayer coating was adapted to truncated-pyramidal nanopores, which was shown to be effective for the minimizing DNA-pore interaction. Further, HfO2 coating by means of atomic layer deposition was employed to prevent the erosion of Si-based pores and to shrink the pore diameter, which enabled reliable investigations of DNA clogging and DNA polymerase docking.For the surface associated phenomena, several findings were made. The lipid bilayer formation on truncated pyramidal nanopores via instantaneous rupture of individual vesicles was quantified based on combined ionic current monitoring and optical observation. The probability of pore clogging appeared to linearly increase with the length of DNA strands and applied bias voltage, which could be attributed a higher probability of knotting and/or folding of longer DNA strands and more frequent translocation events at higher voltage. A free-energy based analytical model was proposed to evaluate the DNA-pore interaction and to interpret observed clogging behavior. Finally, docking of DNA polymerase on nanopore arrays was demonstrated using label-free optical method based on Ca2+ indicator dyes, which may open the avenue to sequencing-by-synthesis enabled by the docked polymerase.
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| 2. |
- Schröder, Stephan, 1979-
(författare)
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Towards Unconventional Applications of Wire Bonding
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents novel heterogeneous integration approaches of wire materials to fabricated and package MEMS devices by exploring unconventional applications of wire bonding technology. Wire bonding, traditionally endemic in the realm of device packaging to establish electrical die-to-package interconnections, is an attractive back-end technology, offering promising features, such as high throughput, flexibility and placement accuracy. Exploiting the advantages of state-of-the-art wire bonding technology and substitute the conventional micro welding approach with an innovative attachment concept, a generic integration platform for a multitude of wire materials is provided. This facilitates a cost-efficient and selective integration, which involves the attachment and shaping of a variety of intrinsically non-bondable wire materials. Furthermore, the selective integration of wire materials provides a simple method to generate complex suspended geometries, which circumvents the need for subsequent processing. The first part of this thesis reports of the integration of non-bondable shape memory alloy wires on wafer-level, which has led to an innovative method to fabricate micro actuators. Moreover, the integration of high performance resistive heating wires on chip-level is utilized to fabricate filament based infrared emitters, targeting non-dispersive infrared gas sensing of alcohol for automotive applications. In the second part, a series of unconventional applications of wire integration using the traditional thermo-sonic wire bonding approach is presented. A novel and low-cost nitric oxide gas sensor is realized by producing vertical bond wires featuring high aspect ratio. Next, the high placement accuracy of wire bonding tools is leveraged to integrate conductive metals cores for fabricating high aspect ratio through silicon vias. Finally, an advanced packaging approach for stress-sensitive MEMS gyroscopes is evaluated, which exclusively utilizes bond wires for realizing the die attachment.
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