Nanosensors

Physical, Chemical, and Biological

Vinod Kumar Khanna

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000331356
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Nanosensors are innovative devices that exploit the unique properties exhibited by matter at the nanoscale. A growing and exciting field, nanosensors have recently spurred considerable research endeavors across the globe, driving a need for the development of new device concepts and engineering nanostructured materials with controlled properties. Nanosensors: Physical, Chemical, and Biological, Second Edition offers a panoramic view of the field and related nanotechnologies with extraordinary clarity and depth.

Presenting an interdisciplinary approach, blending physics, chemistry and biology, this new edition is broad in scope and organised into six parts; beginning with the fundamentals before moving onto nanomaterials and nanofabrication technologies in the second part. The third and fourth parts provide a critical appraisal of physical nanosensors, and explore the chemical and biological categories of nanosensors. The fifth part sheds light on the emerging applications of nanosensors in the sectors of society, industry, and defense and details the cutting-edge applications of state-of-the-art nanosensors in environmental science, food technology, medical diagnostics, and biotechnology. The final part addresses self-powering and networking issues of nanosensors, and provides glimpses of future trends.

This is an ideal reference for researchers and industry professionals engaged in the frontier areas of material science and semiconductor fabrication as well as graduate students in physics and engineering pursuing electrical engineering and electronics courses with a focus on nanoscience and nanotechnology.

Key features:

• Provides an updated, all-encompassing exploration of contemporary nanosensors and highlights the exclusive nanoscale properties on which nanosensors are designed.
• Presents an accessible approach with a question-and-answer format to allow an easy grasp of the intricacies involved in the complex working mechanisms of devices.
• Contains clear, illustrative diagrams enabling the visualization of nanosensor operations, along with worked examples, end of chapter questions, and exhaustive up-to-date bibliographies appended to each chapter.

Part I

Fundamental Concepts of Nanosensors

1
Introduction to Nanosensors

1.1 Getting Started with Nanosensors

This book deals with nanosensors of three key types of signals, namely, physical, chemical, and biological. So, the questions that immediately come to mind are as follows: (1) What is nanotechnology? (2) What are nanosensors? and (3) What is the meaning of the terms ‘physical,” “chemical,” or “biological” alone or when applied to nanosensors?

These questions need to be answered at the outset. Clearly, the starting point in the study of nanosensors will be the basic concepts of physics, chemistry, biology, and nanotechnology Semiconductor electronics will also be introduced. The key terms will be defined. These will enable the reader to recapitulate the preliminary knowledge required to understand the subject matter. They will also help to build up the vocabulary of the new words of nanotechnology that the reader will come across in this book. An exhaustive revision of these fields is not intended – only examples of interesting physical, chemical, and biological materials and phenomena will be provided to highlight the interdisciplinary nature of the subject.

Then, the motivation behind advancement from macro- to micro- and to nanosensors will be explained. The reader will be introduced to the rapidly advancing field of nanosensors and acquainted with different types of nanosensors, dealing with the fundamental principles and classification of nanosensors and laying the foundation upon which the succeeding chapters will be based. The scope and organizational plan of the book will be described.

Let us begin by revising our knowledge of elementary natural sciences.

1.2 Natural Sciences

What is natural science? Natural science is the systematized knowledge of nature and the physical world. It is a science, such as biology, chemistry, physics, and earth science, that deals with objects, phenomena, and laws of nature and the physical world (Brooks 2006). Parts of natural science (physics, chemistry and biology) are described in sections 1.3–1.5 below.

1.3 Physics

1.3.1 Definition of Physics

Physics is the science of forces that exist between objects, the interrelationship between matter and energy, and interactions between the two (Daintith 2010).

1.3.2 Branches of Physics

What are the different branches of physics? Physics is grouped into traditional fields, such as mechanics, properties of matter, heat, light, sound, electricity, and magnetism, as well as in modern extensions, including atomic and nuclear physics, cryogenics, solid-state physics, particle physics, and plasma physics.

1.3.3 Matter: Its States, Materials, and Particles

Matter is something that has weight and occupies space, for example, air, water, gold, iron, and wood. It exists as either a solid, having a definite volume and shape, such as a block of copper; a liquid, having a definite volume but not a definite shape, such as milk and juice; a gas, having neither a definite volume nor a definite shape, for example nitrogen and oxygen; or a plasma, containing a mixture of positive ions and free electrons in almost equal proportions.

Materials are substances out of which things are or can be made, serving as inputs to manufacturing plants. A particle is a very small piece or part, a tiny portion or speck of a material.

1.3.4 Molecules, Atoms, and Atomic Structure

A molecule is the smallest particle of a substance, element (which cannot be broken down into simpler substances), or compound (made of two or more simpler substances) that retains the chemical properties of the substance. An atom is the smallest part or particle of an element, having all the chemical characteristics of that element that uniquely define it, and can take part in a chemical reaction.

Does an isolated atom or molecule possess the bulk physical properties of the element or compound from which it is made? Not necessarily, because the influence of neighboring atoms or molecules, as present in bulk form, is no longer exercised.

Is an atom the ultimately smallest particle or are there further smaller particles? An atom is not the ultimately smallest particle into which matter can be broken down. Still smaller particles exist. Then, what is the structure of the atom? Talking about atomic structure, an atom consists of a central nucleus surrounded by a cloud of one or more electrons (Figure 1.1). The electron has a rest mass m _e of 9.1066 × 10⁻²⁸ gram (g) and a unit negative electric charge of 1.602 × 10⁻¹⁹ coulomb (C). The nucleus is positively charged and contains one or more relatively heavy particles known as protons and neutrons. A proton is positively charged. A proton has a rest mass, denoted by m_p, of approximately 1.673 × 10⁻²⁷ kilogram (kg). A neutron is electrically neutral and has a rest mass, denoted by m_n, of approximately 1.675 × 10⁻²⁷ kg.

FIGURE 1.1 (a) Structure of oxygen atom (atomic number 8, atomic weight 16) containing eight protons (1s² 2p⁶) in the planetary atomic model. (b) Shell model of oxygen atom with two electrons in shell 1 and six electrons in shell 2. (c) Line diagram of oxygen molecule showing double bonds, each consisting of a pair of shared electrons. (d) Two orbitals in oxygen molecule. An orbital is the region surrounding an atomic nucleus indicating the electron’s probable location.

The number of protons in the nucleus of an atom of an element is its atomic number (Z). The total number of protons and neutrons in the nucleus of an atom gives its mass number, atomic weight (A), or relative atomic mass. It is the ratio of the average mass per atom of the naturally occurring form of an element to 1/12th the mass of a carbon-12 isotope; an isotope is one or more atoms of an element having the same atomic number but a different atomic weight. One-twelfth the mass of a carbon-12 atom is called the atomic mass unit (amu) and is = 1.66033 × 10⁻²⁷ kg.

Relative molecular mass or molecular weight of an element or compound is the ratio of the average mass per molecule of its naturally occurring form to 1/12th the mass of the carbon-12 atom and equals the sum of the relative atomic masses of the atoms comprising it.

1.3.5 Mechanics

Mechanics is the branch of physics that deals with forces acting on bodies and the resulting motions. The subject started with Newtonian mechanics that described the translational and rotational motion of bodies under Newton’s three laws of motion, but it was extended to liquids and gases (fluids) as fluid mechanics, to molecular motion as statistical mechanics, and to subatomic particles as quantum mechanics. A quantum is a discrete minimum amount by which a physical quantity changes.

The position of a body in three dimensions is spe...

Table of contents

• Cover
• Half-Title
• Series
• Title
• Copyright
• Dedication
• Contents
• Preface to the Second Edition
• Preface to the First Edition
• Acknowledgments
• Author’s Profile
• About the Book (2nd Edition)
• Abbreviations and Acronyms
• Mathematical Notation
• Part I Fundamental Concepts of Nanosensors
• Part II Nanomaterials and Micro/Nanofabrication Facilities
• Part III Physical Nanosensors
• Part IV Chemical and Biological Nanosensors
• Part V Emerging Applications of Nanosensors
• Part VI Powering, Networking, and Trends of Nanosensors
• Index