Fabrication of a Highly NO2-Sensitive Gas Sensor Based on a Defective ZnO Nanofilm and Using Electron Beam Lithography

Hazardous substances produced by anthropic activities threaten human health and the green environment. Gas sensors, especially those based on metal oxides, are widely used to monitor toxic gases with low cost and efficient performance. In this study, electron beam lithography with two-step exposure was used to minimize the geometries of the gas sensor hotplate to a submicron size in order to reduce the power consumption, reaching 100 °C with 0.09 W. The sensing capabilities of the ZnO nanofilm against NO2 were optimized by introducing an enrichment of oxygen vacancies through N2 calcination at 650 °C. The presence of oxygen vacancies was proven using EDX and XPS. It was found that oxygen vacancies did not significantly change the crystallographic structure of ZnO, but they significantly improved the electrical conductivity and sensing behaviors of ZnO film toward 5 ppm of dry air

Expanding the Scope of Nanobiocatalysis and Nanosensing: Applications of Nanomaterial Constructs

The synergistic interaction between advanced biotechnology and nanotechnology has allowed the development of innovative nanomaterials. Those nanomaterials can conveniently act as supports for enzymes to be employed as nanobiocatalysts and nanosensing constructs. These systems generate a great capacity to improve the biocatalytic potential of enzymes by improving their stability, efficiency, and product yield, as well as facilitating their purification and reuse for various bioprocessing operating cycles. The different specific physicochemical characteristics and the supramolecular nature of the nanocarriers obtained from different economical and abundant sources have allowed the continuous development of functional nanostructures for different industries such as food and agriculture. The remarkable biotechnological potential of nanobiocatalysts and nanosensors has generated applied research and use in different areas such as biofuels, medical diagnosis, medical therapies, environmental bioremediation, and the food industry. The objective of this work is to present the different manufacturing strategies of nanomaterials with various advantages in biocatalysis and nanosensing of various compounds in the industry, providing great benefits to society and the environment.This work was supported by Consejo Nacional de Ciencia y Tecnología (CONACyT) and Tecnologico de Monterrey, Mexico under Sistema Nacional de Investigadores (SNI) program awarded to Rafael Gomes Araújo (CVU: 714118), Manuel Martínez Ruiz (CVU: 418151), Juan Eduardo Sosa Hernández (CVU: 375202), Roberto Parra Saldívar (CVU: 35753), and Hafiz M.N. Iqbal (CVU: 735340).Peer reviewe

Nanostructures and Nanosensors

Cílem této bakalářské práce je představit využití nanotechnologie ve snímacích zařízeních, poskytnout základní informace o nanotechnologii, včetně popisu a klasifikace nanostruktur, a zdůraznit možnost vylepšení výkonu senzoru prostřednictvím nanotechnologie. Tato práce se také zabývá využitím nanodrátu jako součástí senzoru s konfigurací unipolárního tranzistoru. Kvantové tečky a jejich využití v optické detekci jsou také zahrnuty v této práci. Výhody i současná omezení nanosenzorů jsou shrnuty v závěru práce.The aim of this bachelor’s thesis is to introduce the application of nanotechnology in sensing devices, provide fundamental information about nanotechnology including the description and the classification of nanostructures, and emphasise the possibility to enhance sensor operation by means of nanotechnology. The thesis also deals with the application of a nanowire as part of a sensor using the configuration of the field-effect transistor. Quantum dots and their application in optical detection, mainly in the field of nanomedicine, are considered in this thesis as well. The last part is focused on the advantages and current restriction of nanosensors.

Remote plasma assisted fabrication of functional organic and hybrid thin films and supported nanostructures

In general, functional materials are categorized as those materials which possess particular native properties and functions of their own. Examples of these properties are: ferroelectricity, piezoelectricity, magnetism, temperature variations, pressure variations and optical functions. There exists an immense range of functional materials. For instance, optical materials, including lasers, Raman scattering, fluorescence and phosphorescence, are functional materials. Moreover, electrical, magnetics and dielectrics materials are also examples of functional materials, such as semiconducting devices and superconductors, piezoelectrics, ferroelectrics, optical fibres and liquid crystals. On the other hand, functional materials include ceramics, metals, polymers and organic molecules. In recent years, one of the main goals of materials science is the fabrication of new functional materials because of their applications in electronics, informatics and telecommunications. Its continuous development is based on environmental aspects (energy-efficiency, life-cycle issues, recycling or renewable solutions) and cost reduction aspects (energy saving factors in production). The main objective of this thesis is the development of novel multifunctional thin films and supported nanostructures by using remote plasma processes. The thesis is subdivided into eight chapters. At first, Chapter 1 includes the Introduction to the whole work developed throughouth the thesis. Chapter 2 gathers an overview of the thesis in Spanish language. Chapters 3-4 (¿Conformal dielectric organic thin films for molecular electronics¿ and ¿Wetting and anti-freezing properties of adamantane coatings: from thin films to 3D networks¿) study the processability and applications of organic thin films as coatings through its functionalities. These films are fabricated from a precursor of adamantane (C10H16) by RPAVD technique. Separated Chapters 3-4 provide the analysis of two properties of adamantane RPAVD films: dielectric and anti-freezing properties. Later, Annex 1 (¿Adamantane RPAVD: from thin films to 3D networks¿) shows a complete characterization of these adamantane films. After that, this section establishes the control of properties of this type of films, as well as the development of the synthesis of this precursor as supported nanostructures. In addition, it also illustrated that some properties of the films founded in this work can be extended to whole RPAVD materials. Chapter 5, ¿Multicolored emission and lasing in DCM-Adamantane plasma nanocomposites¿ introduces new RPAVD thin films using the combination of a dye laser (4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran, C19H17N3O) and adamantane as precursors. These films exhibit different functionalities that are related to optical properties. In the first instance, this Chapter studies the chemical characterization of the films grown by the mixture of the two precursors. Later, its optical properties are adjusted for a final processing. Finally, it is presented the achievements in the integration of one type of these films in a laser device. Chapter 6 (¿Soft Plasma processing of Organic Nanowires¿) studies a general procedure for the fabrication of hierarchical and hybrid 1D nanostructures from metalloporphyrin, metallophthalocyanine and perylene diimide by plasma processing. The method also provides a template route for the synthesis of supported metal and metal oxide nanostructures by oxygen plasma treatments. In this way, Chapter 7 (¿Highly porous ZnO thin films and 1D nanostructures by remote plasma processing of Zn-phthalocyanine¿) studies the plasma-assisted oxidation of ZnPc in the form of thin film or nanowires to nanostructured ZnO materials. We analyze the characterization of both thin film and supported nanostructures of these hybrid materials. On the other hand, we also evaluate their applications in connection with Annex 2 where we present ZnO thin films from inorganic precursor (ZnEt2) discussed as photonic sensor of oxygen. It is worth to notice that the end of Annex 1 introduces some advances in the synthesis method of functional RPAVD materials. We have developed a new RPAVD structure named nanofabric. Nanofabric is the result of a combination of two accomplishments performed in the present work: the synthesis of hierarchical nanostructures described in Chapter 6, and the process of adamantane by RPAVD detailed in Chapters 3-4 and this Annex