Summary of doctor thesis in Material science: Fabrication of aligned carbon nanotubes and graphene materials for biosensor applications

Objectives of the study: To find out about orientational CNTs and graphene material - the formation, methods of synthesis, properties and applications; optimization of technological conditions to produce high quality oriented CNT and graphene materials using the thermal CVD method.
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Summary of doctor thesis in Material science: Fabrication of aligned carbon nanotubes and graphene materials for biosensor applications 1 MINISTRY OF VIETNAM ACADEMY OF EDUCATION AND TRAINING SCIENCE AND TECHNOLOGY GRADATE UNIVERSITY OF SCIENCE AND TECHNOLOGY  CAO THI THANH FABRICATION OF ALIGNED CARBON NANOTUBES AND GRAPHENE MATERIALS FOR BIOSENSOR APPLICATIONS Major : Electronic materials Code : 62.44.01.23 SUMMARY OF DOCTOR THESIS IN MATERIAL SCIENCE HA NOI - 2018 2 The thesis was completed at Key Laboratory for Electronic Materials and Devices, Institute of Materials Science, Vietnam Academy of Science and Technology. Supervisors: 1. Prof. PhD. Tran Dai Lam 2. PhD. Nguyen Van Chuc Reviewer 1: Reviewer 2: Reviewer 3: The dissertation will be defended at Graduate University of Science and Technology, 18 Hoang Quoc Viet street, Hanoi. Time: .............,.............., 2018 The thesis could be found at: - National Library of Vietnam - Library of Graduate University of Science and Technology - Library of Institute of Science Materials 1 INTRODUCTION 1. The thesis necessity Owing to the unique properties such as: larger surface area, high conductivity, high mechanical stability, excellent electronic mobility, inert chemical properties in solution and high compatible biological properties,... carbon nanotubes (CNTs) and graphene materials are promising to apply in many other fields, such as electronics, energy and fabrication of ultra-small sensors. In particular, field effect transistor (FET) and especially ion sensitive field effect transistor (ISFET) using CNTs/graphene are showed that they have high sensitivity, quick response time and very low detection limit. This is because the CNTs/graphene material in the sensor is in direct contact with the analytical material and directly convert the biological reactions on the electrode surface into electrical signals. Therefore, a small change of analytical material could be detected. Some of the sensors based on FET and ISFET configurations using CNTs and graphene materials have been launched in the detection of certain substances such as glucose, DNA, atrazine, E.coli, etc... In order to improve the potential applications of CNTs and graphene materials, especially, applications for biosensors, we need control the quality of materials such as: density, orientation, defection, purity of CNT as well as the layers, uniform of a graphene film. This is also one of the major challenges for many research groups in Vietnam and other groups in the world. For these reasons, we have chosen the topic of thesis is: “Fabrication of aligned carbon nanotubes and graphene materials for biosensor applications” 2 2. Objectives of the study i) To find out about orientational CNTs and graphene material: the formation, methods of synthesis, properties and applications. ii) Optimization of technological conditions to produce high quality oriented CNT and graphene materials using the thermal CVD method. iii) Application of graphene materials in ISFET- based biosensor to detect the atrazine pesticide residues. 3. Main research contents of the thesis i) Fabrication of vertically aligned CNTs (VA-CNTs) and horizontally aligned CNTs (HA-CNTs) on surface of Si substrate by CVD method. The effect of parameters: catalysis source gas, the temperature and catalysis gas source flow on structure, property and quality of orientational CNTs. ii) Fabrication of graphene by thermal CVD. The effect of parameters: temperature, pressure, catalysis gas flow and surface morphology of catalysis material on the quality of graphene. iii) Production of field effect transistor based on graphene material and application of graphene-FET to detect atrazine residues. 4. Thesis structure: This thesis consists of 145 pages: introduction, four chapters in content, conclusion. The main results were published on 10 journals: 07 articles was published on international journal, 02 article was published on national journal and 01 presentation at an international workshop. 3 CHAPTER 1: INTRODUCTION OF CARBON NANOTUBE MATERIAL This chapter aims to present an overview of CNTs and graphene in the areas of synthesis, electronic structure, properties, information and growth mechanisms, analytical technics and applications. We also present an overview of biosensor such as structure, operation principle as well as the detection mechanism of the field effect transistors based biosensor using graphene material to detect atrazine residues. CHAPTER 2: FABRICATION OF ORIENTED CARBON NANOTUBE BY CHEMICAL VAPOR DEPOSITION 2.1 Thermal CVD system used for fabrication of oriented CNTs Thermal CVD system used for fabrication of oriented CNTs consist of following three main parts: furnace, reaction chamber and gases Figure 2.1. The CVD system for fabrication flow control meter CNTs and graphene at Laboratory of carbon as described in fig. nanomaterials, Institute of Materials Science 2.1. 2.2 Fabrication of VA-CNTs material 2.2.1 Preparation of substrate and catalyst material The silicon substrate with SiO2 layer of 90 nm used to deposit the catalyst particles. The substrate were cut into small pieces of 5 mm  5 mm and cleaned before coating catalyst on the surface. ...