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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Serie: IEEE Press Series on Sensors
- Sprache: Englisch
Solid-State Sensors A thorough and up-to-date introduction to solid-state sensors, materials, fabrication processes, and applications Solid-State Sensors provides a comprehensive introduction to the field, covering fundamental principles, underlying theories, sensor materials, fabrication technologies, current and possible future applications, and more. Presented in a clear and accessible format, this reader-friendly textbook describes the fundamentals and classification of all major types of solid-state sensors, including piezoresistive, capacitive, thermometric, optical bio-chemical, magnetic, and acoustic-based sensors. Throughout the text, the authors offer insight into how different solid-state methods complement each other as well as their respective advantages and disadvantages in relation to specific devices and a variety of state-of-the-art applications. Detailed yet concise chapters include numerous visual illustrations and comparative tables of different subtypes of sensors for a given application. With in-depth discussion of recent developments, current research, and key challenges in the field of solid-state sensors, this volume: * Describes solid-state sensing parameters and their importance in sensor characterization * Explores possible future applications and breakthroughs in associated fields of research * Covers the fundamental principles and relevant equations of sensing phenomena * Discusses promising smart materials that have the potential for sensing applications * Includes an overview of the history, classification, and terminology of sensors With well-balanced coverage of the fundamentals of sensor design, current and emerging applications, and the most recent research developments in the field, Solid-State Sensors is an excellent textbook for advanced students and professionals in disciplines such as Electrical and Electronics Engineering, Physics, Chemistry, and Biomedical Engineering.
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Table of Contents
Cover
Table of Contents
Series Page
Title Page
Copyright Page
About the Authors
Preface
1 Introduction
1.1 Overview
1.2 Evolution of Solid‐State Sensors
1.3 Outline
List of Abbreviations
References
2 Classification and Terminology
2.1 Sensor Components
2.2 Classification of Solid‐State Sensors
2.3 Sensor Terminology
2.4 Conclusion
List of Abbreviations
References
3 Fabrication Technologies
3.1 Introduction
3.2 Deposition
3.3 Exposure‐Based Lithography Techniques
3.4 Soft Lithography Techniques
3.5 Etching
3.6 Doping
3.7 Solution Processed Methods
3.8 Conclusions
List of Abbreviations
References
4 Piezoelectric Sensors
4.1 Overview
4.2 Theory of Piezoelectricity
4.3 Basic Mathematical Formulation
4.4 Constitutive Equations
4.5 Piezoelectric Materials
4.6 Uses of Piezoelectric Materials
4.7 Piezoelectric Transducers as Sensors
4.8 Design of Piezoelectric Devices
4.9 Application of Piezoelectric Sensors
4.10 Conclusions
List of Abbreviations
References
5 Capacitive Sensors
5.1 Overview
5.2 Sensor Construction
5.3 Sensor Architecture
5.4 Classifications of Capacitive Sensors
5.5 Flexible Capacitive Sensors
5.6 Applications
5.7 Prospects and Limitations
List of Abbreviations
References
6 Chemical Sensors
6.1 Introduction
6.2 Materials for Chemical Sensing
6.3 Architectures in Chemical Sensors
6.4 Applications
6.5 Conclusions
List of Abbreviations
References
7 Optical Sensors
7.1 Introduction
7.2 Classifications of Optical Properties
7.3 Materials for Optical Sensing
7.4 Optical Techniques for Sensing
7.5 Fabrication Technique of Optical Sensors
7.6 Applications of Optical Sensing
7.7 Prospects and Limitations
List of Abbreviations
References
8 Magnetic Sensors
8.1 Introduction
8.2 Materials' Magnetic Properties
8.3 Nanomagnetism
8.4 Magnetic Sensing Techniques
8.5 Fabrication and Characterization Technologies
8.6 Magnetic Sensor Applications
8.7 Prospects and Limitations
List of Abbreviations
References
9 Interface Circuits
9.1 Introduction
9.2 Amplifier Circuits
9.3 Excitation Circuits
9.4 Analog‐to‐Digital Converters
9.5 Noise in Sensors and Circuits
9.6 Batteries for Low‐Power Sensors and Wireless Systems
List of Abbreviations
References
Index
IEEE Press Series on Sensors
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Various sectors of solid‐state sensor market and their respective ...
Chapter 2
Table 2.1 List of various measurands for different forms of energy.
Table 2.2 Various sensor applications for different classes of solid‐state s...
Chapter 3
Table 3.1 A comparative study on the characteristics of negative and positiv...
Table 3.2 Wet etchants used in etching and some selected electronic material...
Chapter 4
Table 4.1 Mechanical and electric properties of different piezoelectric mate...
Chapter 5
Table 5.1 Dielectric constants of different materials.
Table 5.2 Dielectric strengths of different materials.
Chapter 7
Table 7.1 Number of total atoms and surface atoms for a nanoparticle with FC...
Chapter 8
Table 8.1 Magnetic properties of selected soft magnetic materials.
Table 8.2 Materials for making a Hall plate along with their desired propert...
List of Illustrations
Chapter 1
Figure 1.1 (a) Global sensor market revenue from 2010 to 2020 and predicted ...
Figure 1.2 (a) The front face of the ancient Astrolabe. (b) Einthoven with h...
Figure 1.3 Timeline of key inventions of solid‐state devices in the electron...
Figure 1.4 Timeline of key contributions in solid‐state sensors.
Figure 1.5 The foundation and pillars of modern‐day solid‐state electronics....
Figure 1.6 (a) Emerging technologies and their (b) timeline of events, which...
Figure 1.7 (a) Artifacts of pottery shards dated to 600 BCE unearthed from a...
Figure 1.8 (a) Charles Ducas patent drawing. (b) A radio made by Paul Eisler...
Figure 1.9 (a) Different IoT‐enabled devices and systems. (b) Schematic repr...
Figure 1.10 Timeline of wearable devices during the last decade.
Chapter 2
Figure 2.1 Block diagram of (a) self‐generating and (b) modulating sensors s...
Figure 2.2 Schematic representations of (a) piezoelectric pressure sensor an...
Figure 2.3 Schematic representation portraying the main classes of solid‐sta...
Figure 2.4 Dart illustration representing the concept of precision and accur...
Figure 2.5 Graphical representation of the response and recovery times of th...
Chapter 3
Figure 3.1 Different types of fabrication techniques and their types.
Figure 3.2 Schematic representation of the (a) sputtering deposition process...
Figure 3.3 Schematic representation of (a) the molecular structure of SiO
2
u...
Figure 3.4 Typical layout of (a) an APCVD reactor, (b) a LPCVD reactor, (c) ...
Figure 3.5 Basic lithographic mask arrangements: (a) shadow printing and (b)...
Figure 3.6 Basic lithographic arrangement for mask projection.
Figure 3.7 Typical arrangement of a mask making machine.
Figure 3.8 Fabrication process flow during photolithography. (a) Deposition ...
Figure 3.9 Schematic representation of EBL set up.
Figure 3.10 Schematic representation of PRINT technique. (a) Fabrication of ...
Figure 3.11 Fabrication process flow for the preparation of (a) Si master te...
Figure 3.12 Fabrication process flow for the preparation of prerequisites – ...
Figure 3.13 Schematic diagram representing the laminar flow patterning.
Figure 3.14 Fabrication process flow of the step and flash imprint lithograp...
Figure 3.15 Process flow of isotropic and anisotropic etching. (a) Sample wi...
Figure 3.16 Schematic cross section of a plasma‐etching system.
Figure 3.17 Hypothetical 2D silicon crystal doped with (a) phosphorus (n‐typ...
Figure 3.18 (a) Theoretical diffusion profile of dopant atoms within a silic...
Figure 3.19 Schematic arrangement of an ion implanter for precise implantati...
Figure 3.20 Schematic representation of the working of inkjet printing.
Figure 3.21 (a) SEM image of microfabricated Si-based microfluidic cantileve...
Figure 3.22 Schematic representation of the working of spray deposition.
Figure 3.23 Schematic representation for the working of screen‐printing tech...
Figure 3.24 Schematic representation of the working of tape casting.
Chapter 4
Figure 4.1 (a) Curie family portrait. Standing are Jacques and Pierre Curie ...
Figure 4.2 (a) Schematic representation of arrangement of negative and posit...
Figure 4.3 Macroscopic crystalline structure showing (a) the random orientat...
Figure 4.4 Schematic representation of piezoelectric material at (a) unstres...
Figure 4.5 Schematic diagram indicating different electrical displacements d...
Figure 4.6 Schematic representation of relative dielectric constant showin...
Figure 4.7 Classification of piezoelectric materials and their examples.
Figure 4.8 Different naturally occurring single‐crystal piezoelectric materi...
Figure 4.9 Display of (a) electrical (
x
) and mechanical (
y
) axes of a piezoe...
Figure 4.10 Schematic representation of wood section in Cartesian coordinate...
Figure 4.11 (a) Representation collagen fibers composed of aligned collagen ...
Figure 4.12 (a) (i) α Phase (ii) β phase, and (iii) γ phase of glycine cryst...
Figure 4.13 Molecular arrangements in (a) unpoled and (b) electrically poled...
Figure 4.14 The transition of (a) BaTiO
3
from (i) tetragonal to (ii) cubic a...
Figure 4.15 Salient features of various piezoelectric ceramics.
Figure 4.16 Schematic representation of the concept of connectivity in piezo...
Figure 4.17 Block diagram representation showing the conversion of mechanica...
Figure 4.18 Schematic representation showing the working of piezoelectric st...
Figure 4.19 (a) Schematic diagram of piezoelectric generator and (b) mechani...
Figure 4.20 Schematic diagram of the piezoelectric pressure sensor demonstra...
Figure 4.21 (a) Schematic representation of a piezoelectric accelerometer an...
Figure 4.22 Three‐dimensional representation of the surface acoustic wave (S...
Figure 4.23 Illustration of QCM‐based piezoelectric bulk acoustic wave senso...
Figure 4.24 Illustration of a piezoelectric crystal in (a) equilibrium, unde...
Figure 4.25 Schematic representation of the working principle of engine knoc...
Figure 4.26 Schematic representation of the working of the stick and slip (a...
Figure 4.27 (a) Schematic representation of the working of the ultrasonic pi...
Figure 4.28 Schematic representation of the working of SONAR devices.
Figure 4.29 Schematic representation of the drop on demand piezoelectric pri...
Figure 4.30 Schematic representation of the internal architecture of ultraso...
Figure 4.31 Representative image of piezoelectric dental scaler showing the ...
Figure 4.32 (a) 3D printed floating water lilies and (b) a biologically insp...
Figure 4.33 Schematic representation of the working of course changing bulle...
Figure 4.34 The schematic representation of the (a) operation of piezoelectr...
Figure 4.35 (a) Newly designed tennis racquet with piezoelectric boost, desi...
Chapter 5
Figure 5.1 Schematic representation of a parallel electrode capacitor under ...
Figure 5.2 Schematic representation of parallel electrode capacitor with (a)...
Figure 5.3 COMSOL simulation showing the variation of electric field with di...
Figure 5.4 Schematic representation of three‐axis force sensor under (a) ini...
Figure 5.5 Parallel electrode capacitor with (a) air
ε
0
and (b) dielect...
Figure 5.6 COMSOL simulation of fringing electric field developed near the a...
Figure 5.7 Parallel electrode capacitor with combination of two capacitances...
Figure 5.8 Equivalent circuit diagram for combination of capacitors connecte...
Figure 5.9 Capacitance with mixed dielectric material.
Figure 5.10 Multielectrode capacitor design with dielectric material of rela...
Figure 5.11 (a) and (b) representing equivalent circuit diagram for the capa...
Figure 5.12 (a) Side view of capacitive sensor with displaceable diaphragms....
Figure 5.13 Schematic representation of (a) absolute, (b) differential, (c) ...
Figure 5.14 Basic liquid‐level sensing system with (a) parallel rod and (b) ...
Figure 5.15 Representation of the (a) fringing electric field emanating from...
Figure 5.16 Schematic representation of metallic ball‐based rotary motion se...
Chapter 6
Figure 6.1 (a) Schematic representation of working biosensor. (b) Artist imp...
Figure 6.2 (a) Caged canaries as primitive gas sensors. (b) Portrait of Scot...
Figure 6.3 (a) The band model of conductive mechanism upon exposure to a tar...
Figure 6.4 Naturally occurring hexagonal honeycomb structure in (a) beehives...
Figure 6.5 (a) Schematic representation of hexagonal lattice of graphene sho...
Figure 6.6 Carbon nanotube configurations with the chiral vector
C
and unit ...
Figure 6.7 Schematic representation of (a) boron nitride (h‐BN) and (b) moly...
Figure 6.8 Classification of biopolymers in terms of type, origin, and monom...
Figure 6.9 Classification of synthetic biopolymers into biodegradable and no...
Figure 6.10 Sources of natural polymers.
Figure 6.11 (a) Molecular structure of sugar furanose ring (b) representatio...
Figure 6.12 (a) Schematic representation of two single strands of polynucleo...
Figure 6.13 Schematic representation of sensing a guest target molecule usin...
Figure 6.14 (a) Schematic representation and (b) TEM image of DNA functional...
Figure 6.15 (a) Microscopic image showing crumpled morphology of graphene fl...
Figure 6.16 Active sensing material deposited on interdigitated electrode (I...
Figure 6.17 Representative image of explosion of a chlorine gas container du...
Figure 6.18 (a) Fabricated array of sensors on GO–chitosan substrate and (b)...
Chapter 7
Figure 7.1 Schematic representation of different optical sensing techniques ...
Figure 7.2 Schematic representation of different optical phenomena such as a...
Figure 7.3 Schematic representation of different kinds of optical processes ...
Figure 7.4 Schematic representation of the different scattering processes (a...
Figure 7.5 Schematic representation of linear and circularly polarized light...
Figure 7.6 Schematic representation of the SPR phenomenon (a) and the oscill...
Figure 7.7 Schematic representation of ZnO nanowire fabrication process usin...
Figure 7.8 Schematic representation of the differential SPR setup. (a) shows...
Figure 7.9 Schematic representation of different gas sensing techniques usin...
Figure 7.10 Schematic representation of different IR sensing techniques for ...
Figure 7.11 This image shows the schematic illustration of colorimetric dete...
Chapter 8
Figure 8.1 The magnetization alignment inside different kinds of materials a...
Figure 8.2 The tunneling junctions between two ferromagnetic materials in (a...
Figure 8.3 The Hall effect experimental setup.
Figure 8.4 (a) Hall plate in voltage mode operation. (b) Hall plate in curre...
Figure 8.5 The biosensing application using a Hall effect sensor (a) and a G...
Figure 8.6 Different sensing mechanisms in brief such as current sensing (a)...
Chapter 9
Figure 9.1 (a) Voltage divider circuit for resistance to voltage conversion....
Figure 9.2 Circuit for shifting of voltage for sensor circuit design.
Figure 9.3 Models for electric battery. (a) Ideal, (b) linear, and (c) Theve...
Figure 9.4 (a) Ripple factor of battery output current connected to a three‐...
Figure 9.5 Ripple factor of battery output current with condenser filters. (...
Figure 9.6 Circuit diagram for three‐phase inverter.
Figure 9.7 Input impedance circuit.
Figure 9.8 Equivalent circuit model of an ideal operational amplifier.
Figure 9.9 Schematic diagram of (a) inverting op‐amp (b) noninverting op‐amp...
Figure 9.10 Schematic diagram of a voltage follower amplifier.
Figure 9.11 Schematic diagram of a general instrumentation amplifier.
Figure 9.12 Schematic diagram of a charge amplifier along with a sensor at i...
Figure 9.13 Op‐amp‐based (a) unipolar current generator and (b) bipolar curr...
Figure 9.14 A circuit for voltage reference with its V‐I characteristics. (a...
Figure 9.15 Square wave generators using (a) logic gates and (b) comparator ...
Figure 9.16 A driver circuit.
Figure 9.17 Typical block diagram of an ADC and a response associated with t...
Figure 9.18 Schematic representation of voltage‐to‐frequency convertor.
Figure 9.19 Architecture of VFCs (a) multivibrator type and (b) charge balan...
Figure 9.20 Dual‐slope‐type ADCs.
Figure 9.21 Successive approximation converter.
Figure 9.22 Magnetic shielding.
Figure 9.23 Circuit with ground plane.
Figure 9.24 Schematic diagram of common ground loops.
Figure 9.25 Schematic diagram of isolation transformer.
Figure 9.26 A node of wireless sensors network.
Figure 9.27 A complete wireless sensor system.
Figure 9.28 Power profile of a node in WSN.
Figure 9.29 Block diagram of energy harvesting wireless node.
Figure 9.30 Graph plotted between voltage and service.
Guide
Cover Page
Series Page
Title Page
Copyright Page
About the Authors
Preface
Table of Contents
Begin Reading
Index
IEEE Press Series on Sensors
WILEY END USER LICENSE AGREEMENT
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IEEE Press445 Hoes LanePiscataway, NJ 08854
IEEE Press Editorial BoardSarah Spurgeon, Editor in Chief
Jón Atli Benediktsson
Behzad Razavi
Jeffrey Reed
Anjan Bose
Jim Lyke
Diomidis Spinellis
James Duncan
Hai Li
Adam Drobot
Amin Moeness
Brian Johnson
Tom Robertazzi
Desineni Subbaram Naidu
Ahmet Murat Tekalp
Solid‐State Sensors
Ambarish Paul
University of Glasgow
Glasgow, UK
Mitradip Bhattacharjee
Indian Institute of Science Education and Research Bhopal
Bhopal, Madhya Pradesh, India
Ravinder Dahiya
Northeastern University
Boston, MA, USA
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Library of Congress Cataloging‐in‐Publication Data:
Names: Paul, Ambarish, author. | Bhattacharjee, Mitradip, author. | Dahiya, Ravinder S., author.Title: Solid-state sensors / Ambarish Paul, Mitradip Bhattacharjee, Ravinder Dahiya.Description: Hoboken, New Jersey : Wiley-IEEE Press, [2024] | Includes index.Identifiers: LCCN 2023040077 (print) | LCCN 2023040078 (ebook) | ISBN 9781119473046 (cloth) | ISBN 9781119473053 (adobe pdf) | ISBN 9781119473077 (epub)Subjects: LCSH: Detectors.Classification: LCC TA165 .P37 2024 (print) | LCC TA165 (ebook) | DDC 621.3815/36--dc23/eng/20230905LC record available at https://lccn.loc.gov/2023040077LC ebook record available at https://lccn.loc.gov/2023040078
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About the Authors
Ambarish Paul
Ambarish Paul obtained his doctoral degree from the Indian Institute of Technology Kharagpur, India, in 2015. He was awarded the Newton International Fellowship 2016 at the University of Glasgow, United Kingdom, where he worked on flexible and biodegradable sensors for medical applications. His research interest includes medical devices, nanomaterials, functionalized biomaterials, bendable electronics, sensors for environmental monitoring, intelligent systems, and robotics. He has authored nearly 17 research articles in international journals and conferences. He is the recipient of Marie Sklodowska‐Curie Seal of Excellence Award by European Union (EU) in 2016 and 2017.
Mitradip Bhattacharjee
Mitradip Bhattacharjee (Senior Member, IEEE) received his PhD degree from the Indian Institute of Technology, Guwahati, India, in 2018. Subsequently, he joined the University of Glasgow, United Kingdom, as a postdoctoral fellow. He is currently an assistant professor with the Electrical Engineering and Computer Science Department, Indian Institute of Science Education and Research (IISER) Bhopal, India, where he is leading the i‐Lab Research Group. His research interests include electronic sensors and systems, biomedical engineering, bioelectronics, flexible/printed and wearable electronics, wireless systems, IoT, micro/nanoelectronics, and reconfigurable sensing antenna. He has authored more than 50 research articles in reputed journals/conferences and filed more than 15 national/international patents. He also has authored several book chapters/books till date. He is recipient of several awards such Marie Sklodowska‐Curie Seal of Excellence Award by the European Commission in 2019, Nanochallenge Award by PSG in 2018, Gandhiyan Young Technological Innovation Award at Rashtrapati Bhavan in 2016, among others. He served as the chair of IEEE sensors council young professionals in 2022. He is also an editorial team member of IEEE Sensors Alert.
Ravinder Dahiya
Ravinder Dahiya is a professor in the Department of Electrical and Computer Engineering at Northeastern University, Boston, United States. His group (Bendable Electronics and Sustainable Technologies [BEST]) conducts research in flexible printed electronics, electronic skin, and their applications in robotics, wearables, and interactive systems. He has authored or co‐authored more than 500 publications, books, and submitted/granted patents and disclosures. He has led or contributed to many international projects.
Prof. Dahiya is the president of IEEE Sensors Council, IEEE Division X Delegate-Elect/Director-Elect (2024) and editor-in-chief of NPJ Flexible Electronics. He launched the IEEE Journal on Flexible Electronics and also served as the founding editor-in-chief of this journal. He has been editorial boards of several other leading journals. He founded the IEEE International Conference on Flexible, Printed Sensors and Systems (IEEE FLEPS) and has served as General Chair or Technical Programme Chair of several international conferences such as IEEE Sensors and IEEE FLEPS. He is recipient of EPSRC Fellowship, Marie Curie Fellowship and Japanese Monbusho Fellowship and has received several awards, including Technical Achievement award from IEEE Sensors Council, Young Investigator Award from Elsevier, and 13 best journal/conference paper awards as author/co-author. He is Fellow of IEEE and the Royal Society of Edinburgh.
Preface
The field of solid‐state sensors has broadened and expanded significantly in the last 20 years. The solid‐state sensors are being used in the development of various devices in medicine, agriculture, industry, transport, environmental control, and other fields. The process of development of new sensors and technologies has been revolutionized with the emergence of printed electronics, flexible substrates, biodegradable materials, nanotechnology, smart materials, integrated devices through IoT, and advanced wireless data transmission systems. To meet the high demands of commercial market for solid‐state sensors, researchers are working on the development of affordable sensing devices with low production cost. Further, to make the sensors suitable for wearable applications, it is necessary to develop sensors with small size and low power consumption.
In this book the readers will find detailed description of the design, development, and applications of capacitive, piezoelectric, chemical, optical, and magnetic solid‐state sensors. This book takes the readers on a journey from the emergence of solid‐state devices through their transition and miniaturization period to the present‐day smart and integrated sensors with remote data access facilities. The aim of this book is to provide a detailed and updated assessment of the new trends in the field of solid‐state sensors in terms of working principles, classifications, design architecture, fabrication techniques, active sensing materials, and new age applications. Since the microfabrication has reached its zenith of application with the advent of state‐of‐the‐art tools and techniques and its versatility with different materials and processes, a chapter is dedicated for the discussion on these fabrication techniques. Further, different fabrication techniques in the form of solution processed routes and custom printed electronics are also discussed in a chapter. As circuit and system are very important aspects of sensor application, a chapter on interface circuits with different circuit components is included in this book. This chapter on interface circuit will help in understanding different circuit components and system aspect associated with the sensor system design. Each chapter presented in this book is written in lucid language and made interesting and attractive to students with the use of illustrations and schematic diagrams. Each chapter has a list of references to make the information accessible to any reader irrespective of their background.
This book will benefit students studying courses in the field of material sciences, chemical engineering, electrical and electronics, physics, environmental sciences, and relevant disciplines. Moreover, researchers and scientists working in the field of sensor design and fabrication, analytical control, and sensor systems will benefit from the contents of this book. Practicing engineers or project managers, who want to be acquainted with solid‐state sensors, can also follow this book for required details and information. This book will also help masters’ students and those in the early stage of research to design new devices and select best architecture for enhanced performance aim for specific applications. We believe that this book covers all aspects of solid‐state sensors from fundamentals of operation to optimum materials and approaches for achieving better sensor performances.
Ambarish Paul, Mitradip Bhattacharjee, and Ravinder Dahiya
1Introduction
1.1 Overview
A sensor is a device which detects or measures a physical, chemical, optical, electrical, and magnetic properties relating to temperature, pressure, strain, molecular finger prints, absorbance, and subsequently records, indicates, or responds to it. The term “solid state” became popular in the beginning of the semiconductor era in the 1960s to distinguish this new technology based on semiconducting materials such as silicon and its doped derivatives, in which the electronic action of such devices occurred within the material, which is in contrast with the vacuum tubes where electronic action occurred in a gaseous state. The solid‐state sensor responds to external variations and induces change in properties of the semiconducting material, thereby producing variations in electric current through the semiconducting material. The measure of this electric current is a manifestation of the amount of external variation also called the measurand. However, nowadays with the advent of new materials, technologies, and smart sensor architectures and scopes, the term “solid state” is also used for devices in which the devices have no moving parts. Again, solid‐state sensors must not be confused with transducers or actuators which react depending on the sensor response. A solid‐state sensor is designed in such a way that the measurand, the physical property to be sensed, exploits a physical phenomenon within the sensor structure. This physical phenomenon if found in traces or is weak may not produce measurable amount of variation in electrical response that can lead to nondetection and poor sensor performance. Such electric signal must be detected by magnifying the weak signals with suitable electronics and signal processing stage. Thus, solid‐state sensor with integrated electronics along with other intelligent computational processes is in high commercial demand.
However, the conventional “solid‐state” semiconductor‐based sensors have transformed largely over the years. With the discovery of new tools and technologies and the exploration of new materials and synthesis techniques the solid‐state sensors have evolved as one of the blooming areas of research because of its promise and the potential to redefine itself. Researchers have developed sensors using metal oxides, ceramics, nanomaterials, polymers, and biomaterials as the active sensing materials on disposable [1], bendable, and ultrathin transparent polymer substrates with no movable parts for different applications [1–8]. Such sensors with no movable parts and capable of generating electronics signals in response to the measurand are considered within the scope of this book. This book discusses the promise, benefits, fabrication techniques, sensing material commonly used, sensor architecture and its role on the performance, sensing strategies, important applications, and new trends for each type of sensors including capacitive, piezoelectric, piezoresistive, optical, chemical, and magnetic. The aim of the book is not only to educate the readers on the scopes and potential of each types of sensors, but also cultivate interest and encourage them to explore new dimensions of multivariant sensing.
1.1.1 Growth in Solid‐State Sensor Market
The late twentieth century has witnessed a burst of technological advances in the field of solid‐state sensors [9–11]. Industry report suggests that sensors especially solid‐state sensors market is expanding its horizon every year [12]. In the present context, this expansion is such that the solid‐state sensor market is comparable to leading markets like that of the computers and the communication market. This is because the solid‐state sensors are being widely used in every aspect of our lives such as of smartphones, other electronic gadgets, automobiles, security systems, and even everyday objects like coffee makers, sanitizer dispensers, blood pressure monitors, and glucometers. In addition to consumer electronics, these sensors find application in Internet of things (IoT), medical, nuclear, defense, aviation, robotics, artificial intelligence (AI), environment, agriculture, and in geophysical and oceanographic explorations.
The requirement for the solid‐state sensing devices have increased considerably over the years (Figure 1.1a) and is also expected to grow subsequently during the decade as predicted in Figure 1.1a, b. This is due to the increasing demand of solid‐state sensors in wide cross‐section of industrial applications. The demand for cost‐efficient, reliable, and high‐performance solid‐state sensor market is also driving the market growth. There is increased use of solid‐state sensors in multiutility devices such as watches and smartphones integrated with sensors, which in turn are assisting the development of solid‐state sensor industry. The segmentation of the solid‐state sensor market is performed based on classification and application. By classification, the market is divided into varied type of sensors and the respective market revenue per year is shown in Table 1.1. Based on application, the market is divided into automotive, oil and gas, consumer electronics, medical, health care, and others. In addition, the pressure and temperature sensor market were valued at $7.21 and $4.99 billion in 2016 and is projected to reach $12.07 and 6.86 billion by 2024, growing with a CAGR of 6.7% and 4.5%, respectively, during the forecast period of 2017–2024. The piezoresistive sensor market generated the highest revenue share in the global pressure sensor market. With the emergence of advance technologies for different gas sensing, the market is expected to be valued at $1.4 billion by 2024 at a CAGR of 6.86% in the forecasting period of 2017–2024. The rising demands of oxygen gas in the healthcare sector such as in the anesthesia machines, ventilators, oxygen monitors, and in automotive and transportation application are driving the oxygen gas sensor market. The consumer electronics market is expected to grow at the highest rate as the gas sensors are believed to be integrated with smartphones and other wearable devices to detect alcohols, carbon dioxide, carbon monoxide, and nitrogen dioxide. The optical sensing market is estimated to grow from $1.12 billion dollars in 2016 to $3.46 billion by 2023 at a CAGR of 15.47% between 2017 and 2023. The demand for optical sensors is attributed to its accuracy and the ability to withstand harsh environments in aerospace, defense sectors, and oil and gas industries. The increasing investments in the R&D activities on optical sensors drive the growth of the market. The magnetic sensors market is expected to reach $4.16 billion by 2022 at a CAGR of $4.16 between 2016 and 2022.
Figure 1.1 (a) Global sensor market revenue from 2010 to 2020 and predicted growth with CAGR of 9.5% for 2021–2025. (b) Global sensor market trends for different devices as predicted by IDTechEx.
Source: (a) Adapted from BCC Research, Allied Market Research.
Table 1.1 Various sectors of solid‐state sensor market and their respective predicted market revenue per year.
Materials/device/sensor market
Prediction until year
Predicted revenue per year (in billions)
Graphene market
2031
$0.7
Fluoropolymer/electronics market
2041
$14
Printed electronic materials market
2031
$6.9
3D printing materials
2030
$18.4
Wearable sensors market
2025
$5
CNT market
2030
$0.750
3D electronics
2030
$3
Advanced photovoltaics market beyond silicon
2040
$40
Sensors market
2041
$250
Printed sensor market
2030
$4.5
Skin sensors technologies
2030
$0.275
Wearable technology
2019 attained
$70
Environmental sensors market
2030
$3.8
Flexible electronics in health care
2030
$8.3
Flexible hybrid electronics
2030
$3
Biosafe polymer market
2030
New market
Harvesting for roads and sensing for IoT and healthcare market for piezo transducers
2030
$1
Piezoelectric‐based sensing market in health care beyond imaging
2029
$1.04
RFID sensor tags and systems
2028
$0.904
Robotic sensing
2027
$16.1
Water and wastewater networks sensor market
2030
$2
Solid‐state batteries
2030
$6
Wearable technology for animals market
2030
$22
1.1.2 Solid‐State Sensors: A Recipe for Smart Sensing Systems
The rapid growth solid‐state sensor market can be attributed to the development of computer‐controlled processes and remote monitoring of industrial process in real time. With the advent of microfabrication and miniaturization of devices, system‐on‐chip (SOC) sensors have drawn significant attention from the researchers from academia and industries. Currently due to the growing demands of on‐chip integrated devices, the class of solid‐state sensors has surpassed the traditional sensing techniques such as the electrochemical and the chromatographic methods in terms of scopes, benefits, and reliability. The development of solid‐state sensors not only promises integrated multiple sensors on a common chip, but also shows potential in closer interfacing with the computers for remote monitoring of various processes which aid computerized manufacturing and process control. There are many types of solid‐state sensors, which are in everyday use or in the different stages of development. They encompass a wide realm of sensing technologies including the chemical sensors (gas and biosensors), physical sensors (e.g. strain, pressure, temperature), acoustic sensors (e.g. bulk and surface acoustic wave devices), optical sensors (optical waveguide, infrared detectors), thermochemistry (e.g. microcalorie and microenthalpy sensors), and magnetic sensors. The major advantages of the solid‐state sensors lie in the simplicity, portability, microfabricability, and reliability. The simplicity in operation of the solid‐state devices relates to the noninvolvement of complex equipment and skilled operators for sensing. The miniaturization compactness and feasibility for on‐chip integration lends portability to solid‐state sensors. The solid‐state sensors are compliant to batch and planar fabrication techniques, which reduces the cost of fabrication. The solid‐state sensors overcome the problems of inconsistent liquid‐phase sensing processes, which make them reliable for long‐term use.
1.2 Evolution of Solid‐State Sensors
1.2.1 Origin and Early Developments in Detection Devices
The need for devices arises from its necessity in public welfare or from the demand in commercial market. Originated in necessity and demand, and conceptualized through suitable understanding, the evolution of sensors went through several scientific challenges and technological advancements, which sometimes spanned over many centuries. The ruler or the measuring rod can be considered as the first measuring tool which was reported to be used in the Indus Valley civilization in 2650 BCE [13]. However, an astronomical device and an inclinometer called the Astrolabe (Figure 1.2a), invented by Apollonius of Perga around 200 BCE, can be regarded as the first device to be invented in the history of mankind [14, 15]. The seismometer, invented by Zhang Heng of the Han dynasty in 132 CE [16], and the Mariner’s compass, invented in Southern India in 400 CE [17], were a few of the early detection equipment that were developed in the Medieval era.
Figure 1.2 (a) The front face of the ancient Astrolabe. (b) Einthoven with his EKG machine. (c) The first vacuum tube invented in 1904 by John Ambrose Fleming.
Sources: (a) Mustafa‐trit20/Wikimedia Commons/CC BY‐SA 4.0. (b) Informa UK Limited.
The evolution of transducer/sensor took place in diverse realms of fields, including those associated with health care originated in the same era but underwent massive transformation through the modern era and continuing in the electronic era (post 1895). One such device which has been through the journey of evolution from its medieval form to its present form is the modern‐day pulse meter. The modern‐day pulse meter supported with wireless features and other physiological sensors and regulated through AI can be considered as a unique example of scientific, technological, and engineering device evolution. The authors have traced back the evolution of pulse meters since its inception when people relied on qualitative diagnosis to a more complex and detailed informative device in its present form. That pulse diagnosis directly related to human health was realized in 350 BCE by Chinese physician Bian Que (401–310 BCE). Later in 305 BCE, the Praxagoras of Cos (340–??1 BCE) [18], the teacher of Herophilus of Chalcedon (335–280 BCE), became the first Greek physician to feel the pulse in order to observe the health of the ill. Having understood the importance of pulse diagnosis, the ancient researchers felt the need for a device that would help them to count the heart beat and investigate the pulse rate in unhealthy humans. In 290 BCE, Greek physician Herophilus of Chalcedon (335–280 BCE) devised a water clock to count the human pulse to analyze the rhythm and heartbeat, though it was not considered as a complete device [19]. Although the ancient inventions and breakthroughs are not well documented, but are reported in scriptures. A Polish Professor Joseph Struthius (1510–1568) was the first to present a graphic image of the pulse in 1555 and introduced the concept of a device that could mechanically register the pulse [20]. It was after the Italian physician, mathematician, and philosopher Galilei (1564–1642) in 1601 who correlated his own pulse with the pendulum movements of a clock, an Italian Professor of Medicine Santorio Santorio (1561–1636) in the year 1602 successfully counted the pulse using this pendulum [21]. This was the first pulse meter. Incidentally, Galilei and Santorio invented the thermoscope and the clinical thermometer in 1593 and 1625, respectively [22]. In 1707, an English physician Sir John Floyer (1649–1734) invented the “one minute pulse watch” for a correct pulse measurement. Floyer was one of the first to measure the pulse in daily practice and used the device to obtain accurate pulse rate measurements [23]. The devices invented in the modern era were mostly mechanical devices with moving parts and was only considered as mechanical devices.
A more advanced electronic record of heartbeat was obtained in 1872 by Alexander Muirhead when he attached wires on the wrist of the patient. Augustus Waller invented an ECG machine in 1887, however the more practical and sensitive one was invented by Einthoven in 1901 [24] (Figure 1.2b). In 1924, Einthoven was awarded the Nobel Prize in Medicine for his pioneering work in developing the ECG. The electronic era commenced with the discovery of wireless transmission in 1895 by Russian scientists [25, 26] and riding on the advancements in electronics and miniaturization, wireless ECG‐based heart rate monitor was invented in 1977 by Polar Electro as a training tool for the Finnish National Cross Country Ski Team [27]. In 2005, Textronics, Inc., introduced the first garment with integrated heart sensors in the form of a sports bra [28]. Special materials in the sports bra sense heart rate from the body and transmit it to a wrist receiver. Recently in 2020, researchers have developed smart healthcare system in IoT environment that can monitor a patient’s basic health signs in real‐time using integrated heart beat sensor, body temperature sensor, room temperature sensor, CO sensor, and CO2 sensor in a sensor system [29].
Earlier the invention of thermionic emission in 1873 marked the beginning of a new era which revolutionized the scope of detection devices. Thomas Edison’s discovery of electric current in 1883 was a huge leap in mankind and laid the foundation to the present‐day electronics (Figure 1.3). Following the discovery of unilateral conduction across the junction of a semiconductor (Galena crystal) and a metal by KF Braun in 1974, JC Bose was the first to use this crystal semiconductor for detecting radiowaves in 1894 [30]. This concept of rectifying contact between metal semiconductor junctions was used by Braun and GW Pickard to develop radiowave detector (commonly called Cat whisker detector) in which they replaced Galena crystal with silicon [31]. The Cat whisker detector was the first solid‐state electronic detection equipment that was patented in 1906. In 1916 and 1917, Paul Langevin and Chilowsky developed the first ultrasonic submarine detector using an electrostatic method (singing condenser) [32]. The amount of time taken by the signal to travel to the enemy submarine and echo back to the ship on which the device was mounted was used to calculate the distance under water. The first wearable solid‐state detection equipment was the polygraph which was invented in 1921 by a medical student named John Augustus Larson and worked on the Galvanic response of the skin [33]. Subsequent inventions during the modern age continued in different field of research until the invention of the transistor in 1947 which boosted the field of solid‐state electronics and sensing systems.
Figure 1.3 Timeline of key inventions of solid‐state devices in the electronic era.
1.2.2 Solid‐State Electronics: Post Transistor Era
Vacuum tubes, invented in 1904 by John Ambrose Fleming (Figure 1.2c), formed the basic electronic components for use in television, radar, telephone, and industrial process control applications [34]. The scientific community turned toward solid‐state electronic materials as alternative solutions to overcome the challenges of vacuum tube‐based devices that were widely used as amplifiers and rectifiers prior to 1940s. The invention of semiconductor devices in the late 1950s led to the development of solid‐state devices which are smaller, efficient, reliable, and cost‐effective than the vacuum tube‐based devices (Figure 1.4). Furthermore, the solid‐state devices were associated with low heat dissipation and fast response. The solid‐state devices work on the principle of electronic conduction in the material in contrary to the vacuum tube devices which operate through thermionic emission. With the advent of microfabrication techniques of devices, the demand for solid‐state (semiconductor) devices increased manifold due to their batch fabricability which cuts down processing cost. Thus, the rise of semiconducting materials and solid‐state devices provided a new dimension to the field of electronics and associated devices. The invention of transistors by American Physicists John Bardeen, Walter Brattain, and William Shockley in 1947 at the Bell Labs virtually redefined the modern‐day electronics [35, 36]. This transistor (Figure 1.5a) was based on point contact configuration and paved the way for cheaper radios, televisions, calculators, computers, and other devices. Bardeen, Walter, and Shockley (Figure 1.5b) were awarded with the Nobel Prize in Physics in the year 1956 for their study on semiconductors and the discovery of the transistor effect, and later in the year 2009 this feat was acknowledged on the list of IEEE milestones in electronics. Shockley continued his studies on semiconductor and along with Gordon Teal and Morgan Sparks successfully demonstrated the working of N‐P‐N bipolar transistor in the year 1950 (Figure 1.5c). The striking advantage of transistors lies in the potential use as amplifiers and switches. Due to the small size and energy efficiency of the transistors, it was widely used in the design of complex electronic circuits with high switching speeds and energy efficiency.
Figure 1.4 Timeline of key contributions in solid‐state sensors.
Figure 1.5 The foundation and pillars of modern‐day solid‐state electronics. (a) The first transistor of the world, born in Bell Labs in 1947, invented by (b) the American Physicists John Bardeen (L), Walter Brattain, and William Shockley (R). (c) Sparks N‐P‐N bipolar transistor of 1950. (d) Jack Kilby with his invented first pocket calculator. (e) Robert Noyce with his invented monolithic IC‐based motherboard. (f) The first monolithic (2D) integrated circuit developed at Fairchild Semiconductor in 1959 by R. Noyce. Kilby and Noyce are recognized as the inventors of the microchip. Kilby received the Nobel Prize in year 2000 for his contribution to integrated circuit.
Sources: (b) AT&T/Wikipedia Commons/public domain. (d) The Library of Congress. (e) Intel Free Press/Wikipedia Commons/CC BY‐SA 2.0. (f) Fairchild/Courtesy of the Computer History Museum.
The need for the miniaturization of electrical components arose when they were required to be assembled on a single chip. Miniaturization further enhances the energy efficiency of the circuit and reduces the time lag in response. Miniaturized devices on IC boards were manufactured by Jack Kilby at Texas Instruments, and Robert Noyce at Fairchild Semiconductor in 1958 and 1959, respectively. Researchers were successful in fabricating not only transistors but also resistors, capacitors, and diodes on a single monolithic layout to form an electronic chip. Kilby used germanium and Noyce used silicon for the semiconductor material. In 1959, both parties applied for patents. Jack Kilby (Figure 1.5d) and Texas Instruments received US patent #3,138,743 for miniaturized electronic circuits [37]. Robert Noyce (Figure 1.5e) and the Fairchild Semiconductor Corporation received US patent #2,981,877 for a silicon‐based integrated circuit [38]. In 1961, the first commercially available integrated circuits (Figure 1.5f) came from the Fairchild Semiconductor Corporation. All computers then started to be made using chips instead of the individual transistors and their accompanying parts. Jack Kilby holds patents on over 60 inventions and is also well‐known as the inventor of the portable calculator (1967) [39, 40] (Figure 1.5d).
With the advent of miniaturization and advanced microfabrication technique, researchers designed new devices aimed at different applications. As evident from published literature, the researchers have extensively worked on different devices and sensors and classified them in accordance with the transduction principle used in the device. Although the terms “sensor” and “transducer” are often used as synonyms, the American National Standards Institute (ANSI) standard in 1975 preferred the latter over the former [41]. However, the scientific community has adopted the term “sensor” to define a device which provides a usable output in response to a specific measurand and thus is commonly used in scientific articles. The output of a sensor may be any form of energy. Many early sensors converted (by transduction) a physical measurand to mechanical energy; for example, pneumatic energy was used for fluid controls and mechanical energy for kinematic control. However, the introduction of solid‐state electronics created new avenues for the development of sensor systems aided by computer‐based controls, archiving/recording, and visual display. The modern‐day sensor system is often associated with algorithms, AI, and other techniques which require electrical interfacing with microchips and computer‐aided controls, thereby broadening the definition of a sensor to include the systems interface and signal conditioning features that form an integral part of the sensing system. With progress in optical computing and information processing, a new class of sensors, which involve the transduction of energy into an optical form, is likely. Thus, the definition of a “sensor” is likely to continue evolving with time.
1.2.3 Emergence of New Technologies
The evolution of solid‐state electronics and its contribution in the field of solid‐state sensors is largely attributed to the emergence of new technologies which facilitated the transformation of different aspects of solid‐state sensors since its origin. Emergence of new technologies and their advancements over the years (Figure 1.6) have led to technological convergence of their key features toward the evolution and transformation of solid‐state electronics that have forced scientists to setup new benchmarks in defining solid‐state sensors. This technological convergence has shifted the paradigm of research in solid‐state sensors from semiconductor electronics to a more open‐ended approach. In this section, we will discuss about the key technologies that helped transform solid‐state research. The key new technologies with their evolutionary timeline are represented in Figure 1.6.
Figure 1.6 (a) Emerging technologies and their (b) timeline of events, which lead to the evolution of solid‐state sensors.
1.2.3.1 Thin‐Film Technology
The thin‐film technology evolved at the end of the nineteenth century when Drude et al. [42] in 1889 found unusual properties of materials deposited on the walls of the glass discharge tubes, which were different from their bulk counterpart. Over the years, thin films of different materials deposited by wide range of techniques including physical (1940s) and chemical (1970s), vapor deposition, atomic layer deposition, molecular beam epitaxy (1980s), spin coating, dip coating, sol gel, and Langmuir Blodgett method have been well characterized and understood by electron diffraction method (1927), electron microscopy (1940), surface analytical methods (1960s), atomic resolution surface imaging techniques like STM and AFM (1980), and ultrahigh‐resolution TEM (1990). The advent of more advanced thin‐film deposition and characterization techniques such as UHV TEM, fast STM, and synchrotron in early twenty‐first century has boosted the solid‐state sensor industry due to the thickness controllability, thus providing tunability in sensor performance. Thin films have taken a dominant role in revolutionizing the development of new active and passive sensor elements which have led to a drastic metamorphosis of the electronic devices especially the solid‐state sensors. The physical and chemical properties of the thin film largely depend on the material, microscopic structure, and the parameters (e.g. temperature and pressure) utilized to generate the desired microstructure. The microstructure in the thin‐film technology relates to the phase state, morphology of the grains and surfaces, orientations of the crystals planes, texture, chemical composition, homogeneity, and the substrate and thin‐film interface. The key feature of the thin‐film technology lies in the evolution of self‐organized structure by atom by atom adding process at temperatures far from dynamic equilibrium which allows controlled synthesis of metastable phases and artificial structures and multilayers [43]. This self‐organization in thin film is a thermal activated process and initiates with nucleation through migration of atoms, followed by crystal growth by surface diffusion, and grain growth and restructuring by bulk diffusion [44]. However, contaminations can produce adverse effect on the desired structure and property. The evolution of the thin‐film technology is truly the backbone for the growth and widespread acceptance of modern‐day solid‐state sensors.
1.2.3.2 Advancements in Micro‐ and Nanofabrication
The inventions of the transistors and integrated circuit in the 1940s and 1950s, respectively, gave rise to a miniaturization trend in electronics. Miniaturization through microfabrication and micromachining has revolutionized the world of solid‐state sensors. These microfabrication processes have evolved and been modified into advanced technologies that are pushing the boundaries of resolution, feature sizes, and aspect ratios. The term microfabrication was coined by the semiconductor industry. Microfabrication is a multiple step sequence of photolithographic and chemical processing which are used to make microscopic devices and electronic circuits on silicon, polymer, and other biomaterials substrates (rigid or flexible).
With the improvement in microfabrication techniques, smaller and more complex integrated circuits were built, which facilitated the dense packing of electronic components on a given area of the microchip. Due to the extremely small dimension of the structures certain high‐tech tools must be used when performing microfabrication work. The major concepts and principles of microfabrication are photolithography, doping, deposition, etching, bonding, and polishing. A typical microdevice is fabricated by a sequence of microfabrication steps including micromachining, deposition, followed by patterning the film with various microfeatures using photolithography and subsequently etching parts of the undesired area. These processes are detailed in Chapter 2. Industrial microfabrication process is a cumbersome sequence of events where a typical memory chip requires approximately 30 lithography, 10 oxidation, 20 etching, and 10 doping steps to fabricate. Microfabrication is used in the development of integrated circuits on a chip, most of the miniaturized sensors including the semiconductors, microfluidic devices, solid‐state sensors, MEMS, and BioMEMS.
Thin film plays a key role in microfabrication where microchips are typically created using multiple thin films. For electronic devices, the patterned films contain conductive metals that allow for the flow of electricity, while for optical devices, thin films are in the form of reflective or transparent films to improve visibility and clarity. The thin film may also be chemical and biological materials in the form of active sensing or encapsulation material often found in medical devices and gas sensors. Dielectric thin films of polymers are used in capacitive sensors and gate dielectric as the insulation material.
The process of microfabrication is not only limited to the deposition patterning and etching of polymers and semiconducting materials, but also offers a way to produce homogeneous monodisperse particles that are not only spherical, but having controlled or asymmetrical shapes and architectures with a specific size to be fabricated, which is not possible with other methods [45, 46]. Using microfabrication techniques such as particle replication in nonwetting templates [47], microcontact hot printing [48], step and flash imprint lithography [49], and hydrogel template [50] achieve such feat. Microfabrication techniques are used to generate patterns of cells on surfaces. This cellular patterning is a necessary component for cell‐based biosensors, cell culture analogs, tissue engineering, and fundamental studies of cell biology [51]. Moreover, alternative techniques, such as microcontact printing [52, 53], microfluidic patterning using microchannels [54, 55], and laminar flow patterning [56], have been developed for use in biological applications. Microfabrication is even used in advanced manufacturing processes for engineered neural prosthetics where high‐resolution neuroelectrodes are fabricated with the aim of reducing the size of the electronic component. This is achieved by 2D printing of neural arrays or fabricating topographical and biochemical features on the surface of engineered neuroelectrode [57].
1.2.3.3 Emergence of Nanotechnology
The emergence and subsequent evolution of nanomaterials have revolutionized research in the field of materials science. The convergence of nanomaterial and several microfabrication techniques have led to diverse sensors with different applications [58–63]. The reduction of particle size and tuning the particle morphology of nanomaterials from micro to nano size has led to unique properties with versatile applications. The reason for the nanomaterials to exhibit unique/enhanced properties is due to the large surface‐to‐volume ratio and quantum confinement effect. The word nanoscience refers to the study, manipulation, and engineering of matter, particles, and structures on the nanometer scale (one millionth of a millimeter). Due to the quantum mechanical effects, the properties of materials in nanoscale differ from the properties of the same material in bulk form. Material properties, such as electrical, optical, thermal, and mechanical properties, are governed by the morphology and particle size of the nanomaterial, where properties of materials larger than 100 nm tend to show bulk properties. Nanotechnology is the application of nanoscience leading to the use of new nanomaterials in sensors and devices. Due to tunable properties of nanomaterials, nanotechnology has the capability and promise to provide us with custom‐made materials and products with new enhanced properties, new nanoelectronics components, new types of “smart” medicines and sensors, and even interfaces between electronics and biological systems.
Although the field of nanoscience and nanotechnology is relatively new and scientific developments in these fields bloomed after 1990, the key concepts of these branches of science were practiced over a longer period of time where the earliest evidence dates back to 600 BCE. Pottery shards excavated from Keeladi in India's southern state Tamil Nadu and reported in the year 2020 showed unique black coating on the inner surface of the pottery, which was investigated by the Indian researchers at the Vellore Institute of Technology, India, found to be carbon nanotubes [64] (Figure 1.7a). The use of metal nanoparticles in the fourth century Roman era was evidenced in the Lycurgus Cup which is kept in the British Museum. The glass contains gold–silver nanoparticles which are distributed in such a way that it appears green in daylight, but changes to red, when illuminated from the inside. The Damascus steel sword from the Mesopotamian civilization made between 300 and 1700 CE contained nanoscale wires and tube‐like structures which exceptionally enhanced the sharp cutting edge of the sword. However, the re‐emergence of nanotechnology in the 1980s was attributed jointly to the invention of advanced experimental tools such as scanning tunneling microscope, invention of fullerenes (Figure 1.7b), and elucidation of the conceptual framework of nanotechnology in 1986 [65]. The growing awareness on nanotechnology led to the discovery of carbon nanotubes in 1991 [66], which triggered multiple avenues of research and led to understanding of peculiar material properties in nanoscale, opening up applications in diverse fields.
Figure 1.7 (a) Artifacts of pottery shards dated to 600 BCE unearthed from an archaeological site in Keeladi, Tamil Nadu showed evidences of carbon nanotubes. (b) Molecular structure of Fullerene, an allotrope of carbon discovered in 1986.
Sources: (a) Springer Nature Limited. (b) The Trustees of the British Museum.
