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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Towards Automated Nanomanipulation under Scanning Electron Microscopy

Ye, Xutao 27 November 2012 (has links)
Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial’s properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires’ electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.
2

Towards Automated Nanomanipulation under Scanning Electron Microscopy

Ye, Xutao 27 November 2012 (has links)
Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial’s properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires’ electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.
3

Nanoscale Materials Applications: Thermoelectrical, Biological, and Optical Applications with Nanomanipulation Technology

Lee, Kyung-Min 08 1900 (has links)
In a sub-wavelength scale, even approaching to the atomic scale, nanoscale physics shows various novel phenomena. Since it has been named, nanoscience and nanotechnology has been employed to explore and exploit this small scale world. For example, with various functionalized features, nanowire (NW) has been making its leading position in the researches of physics, chemistry, biology, and engineering as a miniaturized building block. Its individual characteristic shows superior and unique features compared with its bulk counterpart. As one part of these research efforts and progresses, and with a part of the fulfillment of degree study, novel methodologies and device structures in nanoscale were devised and developed to show the abilities of high performing thermoelectrical, biological, and optical applications. A single β-SiC NW was characterized for its thermoelectric properties (thermal conductivity, Seebeck coefficient, and figure of merit) to compare with its bulk counterpart. The combined structure of Ag NW and ND was made to exhibit its ability of clear imaging of a fluorescent cell. And a plasmonic nanosture of silver (Ag) nanodot array and a β-SiC NW was fabricated to show a high efficient light harvesting device that allows us to make a better efficient solar cell. Novel nanomanipulation techniques were developed and employed in order to fabricate all of these measurement platforms. Additionally, one of these methodological approaches was used to successfully isolate a few layer graphene.
4

MEMS and Robotics-based Manipulation and Characterization of Micro and Nanomaterials

Zhang, Yong 19 January 2012 (has links)
Advances in the synthesis of micrometer and nanometer-sized materials have resulted in a range of novel materials having unique properties. Characterizing those materials is important for understanding their properties and exploring their applications. Physically manipulating those materials is important for constructing devices. This thesis develops tools and techniques for the manipulation and characterization of micro and nanomaterials. A microelectromechanical systems (MEMS) microgripper is developed to pick and place micro-objects, achieving high repeatability, accuracy, and speed. The adhesion forces at the microscale are overcome by actively releasing the adhered micro-object from the microgripper. A microrobotic system is built based on this microgripper and realizes automated pick-and-place of microspheres to form patterns. To characterize the electrical properties of one-dimensional nanomaterials, a nanorobotic system is developed to control four nanomanipulators for automated four-point probe measurement of individual nanowires inside a scanning electron microscope (SEM). SEM is used as a vision sensor to realize visual servo control and contact detection. To characterize the electromechanical properties of individual nanowires, a MEMS device is designed and fabricated that is capable of simultaneous tensile testing and current-voltage measurement of a nanowire specimen. A nanomanipulation procedure is developed to transfer a single nanowire from its growth substrate to the MEMS device in SEM. The piezoresistive properties of silicon nanowires are characterized. A nanomanipulation system is developed that is capable of being mounted onto and demounted from the SEM specimen stage without opening the high-vacuum chamber. The system architecture allows the nanomanipulators to be transferred through the SEM load-lock. This advance facilitates the replacement of end-effectors and circumvents chamber contamination due to venting.
5

MEMS and Robotics-based Manipulation and Characterization of Micro and Nanomaterials

Zhang, Yong 19 January 2012 (has links)
Advances in the synthesis of micrometer and nanometer-sized materials have resulted in a range of novel materials having unique properties. Characterizing those materials is important for understanding their properties and exploring their applications. Physically manipulating those materials is important for constructing devices. This thesis develops tools and techniques for the manipulation and characterization of micro and nanomaterials. A microelectromechanical systems (MEMS) microgripper is developed to pick and place micro-objects, achieving high repeatability, accuracy, and speed. The adhesion forces at the microscale are overcome by actively releasing the adhered micro-object from the microgripper. A microrobotic system is built based on this microgripper and realizes automated pick-and-place of microspheres to form patterns. To characterize the electrical properties of one-dimensional nanomaterials, a nanorobotic system is developed to control four nanomanipulators for automated four-point probe measurement of individual nanowires inside a scanning electron microscope (SEM). SEM is used as a vision sensor to realize visual servo control and contact detection. To characterize the electromechanical properties of individual nanowires, a MEMS device is designed and fabricated that is capable of simultaneous tensile testing and current-voltage measurement of a nanowire specimen. A nanomanipulation procedure is developed to transfer a single nanowire from its growth substrate to the MEMS device in SEM. The piezoresistive properties of silicon nanowires are characterized. A nanomanipulation system is developed that is capable of being mounted onto and demounted from the SEM specimen stage without opening the high-vacuum chamber. The system architecture allows the nanomanipulators to be transferred through the SEM load-lock. This advance facilitates the replacement of end-effectors and circumvents chamber contamination due to venting.
6

Manipulating fluorescence dynamics in semiconductor quantum dots and metal nanostructures

Ratchford, Daniel Cole 06 February 2012 (has links)
Recent scientific progress has resulted in the development of sophisticated hybrid nanostructures composed of semiconductor and metal nanoparticles. These hybrid structures promise to produce a new generation of nanoscale optoelectronic devices that combine the best attributes of each component material. The optical response of metal nanostructures is dominated by surface plasmon resonances which create large local electromagnetic field enhancements. When coupled to surrounding semiconductor components, the enhanced local fields result in strong absorption/emission, optical gain, and nonlinear effects. Although hybrid nanostructures are poised to be utilized in a variety of applications, serious hurdles for the design of new devices remain. These difficulties largely result from a poor understanding of how the structural components interact at the nanoscale. The interactions strongly depend on the exact composition and geometry of the structure, and therefore, a quantitative comparison between theory and experiment is often difficult to achieve. Colloidal semiconductor quantum dots are strong candidates for integration with metal nanostructures because they have a variety of desirable optical properties, such as tunable emission and long term photostability. However, one potential drawback of colloidal quantum dots is the intermittency in their fluorescence (commonly referred to as “blinking”). Blinking was first observed over a decade ago, yet there is still no complete theory to explain why it occurs. In spite of the lack of a full theoretical explanation, multiple methods have been used to reduce blinking behavior, including modifying quantum dot interfaces and coupling quantum dots with metal nanostructures. This thesis focuses on studying the coupling between colloidal quantum dots and metal nanoparticles in simple model systems. Atomic force microscopy nanomanipulation is used to assemble the hybrid structures with a controlled geometry. The experimental studies report for the first time the modified fluorescence decay, emission intensity, and blinking of a single quantum dot coupled to a single Au nanoparticle. Since the geometry of the structure is known, these studies provide reliable information on the interparticle coupling, and quantitative experimental results are shown to be consistent with classical electrodynamic theories. / text
7

Nanoscale Manipulation under Scanning Electron Microscopy

Chen, Ko-Lun Brandon 05 March 2014 (has links)
A nanomanipulation system operating inside a scanning electron microscope (SEM) enables visual observation and physical interactions with objects at the nanometer scale. Compared to SEM that is a powerful imaging platform (‘eyes’), the development of nanomanipulation systems (‘hands) and techniques for transporting, modifying, and interacting with micro/nanoscaled objects is lagging behind. Two generations of nanomanipulation systems were developed with high SEM compatibility. The vacuum load-lock feature allows setup/sample/end-tools changes to be made within minutes instead of hours as with existing nanomanipulation systems. The integrated high resolution encoders and automation features significantly ease the skill dependency in nanomanipulation. Its small shape factor minimizes effects on SEM imaging performance, and does not restrict the use of the many detectors inside a SEM. The new nanomanipulation systems were applied to the manipulation of sub-cellular structures and the characterization of nano-structures. The first application involves the development of a technique to surgically extract sub-micrometer-sized subnuclear structures within a single cell’s nucleus, followed by biochemical analysis to amplify and sequence the genes contained within. Enabled by the technique, four novel genomic loci associations with promyelocytic leukemia nuclear bodies (PML NB) were discovered in Jurkat cells. The second application targets automated probing of nanostructures under poor imaging conditions. Through real-time image drift compensation and visual servoing of the nano probes, automated probing of nanostructures was achieved with a high success rate and a speed at least three times higher than skilled operator. To enhance the functions of the nanomanipulation system, new types of end-effectors were also developed. A MEMS tool with changeable tool tips was design and prototyped. In-situ (i.e., inside SEM) tool tip change was demonstrated for gripping objects that vary in size by two orders of magnitude (15 um to 100 nm) with a single microgripper body. Furthermore, a microfabrication process was developed to produce changeable nano-spatulas with tip size less than 10 nm, intended for use in the subnuclear structure extraction work. Finally, a local precursor sublimation technique compatible with the nanomanipulation system was developed for enhancing electron beam induced deposition (EBID) inside the SEM.
8

Nanoscale Manipulation under Scanning Electron Microscopy

Chen, Ko-Lun Brandon 05 March 2014 (has links)
A nanomanipulation system operating inside a scanning electron microscope (SEM) enables visual observation and physical interactions with objects at the nanometer scale. Compared to SEM that is a powerful imaging platform (‘eyes’), the development of nanomanipulation systems (‘hands) and techniques for transporting, modifying, and interacting with micro/nanoscaled objects is lagging behind. Two generations of nanomanipulation systems were developed with high SEM compatibility. The vacuum load-lock feature allows setup/sample/end-tools changes to be made within minutes instead of hours as with existing nanomanipulation systems. The integrated high resolution encoders and automation features significantly ease the skill dependency in nanomanipulation. Its small shape factor minimizes effects on SEM imaging performance, and does not restrict the use of the many detectors inside a SEM. The new nanomanipulation systems were applied to the manipulation of sub-cellular structures and the characterization of nano-structures. The first application involves the development of a technique to surgically extract sub-micrometer-sized subnuclear structures within a single cell’s nucleus, followed by biochemical analysis to amplify and sequence the genes contained within. Enabled by the technique, four novel genomic loci associations with promyelocytic leukemia nuclear bodies (PML NB) were discovered in Jurkat cells. The second application targets automated probing of nanostructures under poor imaging conditions. Through real-time image drift compensation and visual servoing of the nano probes, automated probing of nanostructures was achieved with a high success rate and a speed at least three times higher than skilled operator. To enhance the functions of the nanomanipulation system, new types of end-effectors were also developed. A MEMS tool with changeable tool tips was design and prototyped. In-situ (i.e., inside SEM) tool tip change was demonstrated for gripping objects that vary in size by two orders of magnitude (15 um to 100 nm) with a single microgripper body. Furthermore, a microfabrication process was developed to produce changeable nano-spatulas with tip size less than 10 nm, intended for use in the subnuclear structure extraction work. Finally, a local precursor sublimation technique compatible with the nanomanipulation system was developed for enhancing electron beam induced deposition (EBID) inside the SEM.
9

Development of a 6-degree-of-freedom magnetically levitated instrument with nanometer precision

Gu, Jie 30 September 2004 (has links)
This thesis presents the design and fabrication of a novel magnetically levitated (maglev) device with six-degree-of-freedom motion capability at nanometer precision. The applications of this device are manufacture of nanoscale structures, assembly of microparts, vibration isolation of delicate instrumentation, and telerobotics. In this thesis, a single-moving stage is levitated by six maglev actuators. The total mass of the moving stage is 0.2126 kg. Three laser interferometers and three capacitance sensors are used to gather the position information. User interface and real-time control routines are implemented digitally on a VME PC and a digital-signal-processor (DSP) board. The underlying mechanical design and fabrication, electrical system setup, control system design, noise analysis, and test results are presented in this thesis. Test results show a quick step response in all six axes and a resolution of 2.5 nm rms in horizontal motion and 25 nm rms in vertical motion.
10

AFM-Based Mechanical Nanomanipulation

January 2011 (has links)
Advances in several research areas increase the need for more sophisticated fabrication techniques and better performing materials. Tackling this problem from a bottom-up perspective is currently an active field of research. The bottom-up fabrication procedure offers sub-nanometer accurate manipulation. At this time, candidates to achieve nanomanipulation include chemical (self-assembly), biotechnology methods (DNA-based), or using controllable physical forces (e.g. electrokinetic forces, mechanical forces). In this thesis, new methods and techniques for mechanical nanomanipulation using probe force interaction are developed. The considered probes are commonly used in Atomic Force Microscopes (AFMs) for high resolution imaging. AFM-based mechanical nanomanipulation will enable arranging nanoscale entities such as nanotubes and molecules in a precise and controlled manner to assemble and produce novel devices and systems at the nanoscale. The novelty of this research stems from the development of new modeling of the physics and mechanics of the tip interaction with nanoscale entities, coupled with the development of new smart cantilevers with multiple degrees of freedom. The gained knowledge from the conducted simulations and analysis is expected to enable true precision and repeatability of nanomanipulation tasks which is not feasible with existing methods and technologies.

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