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- Herausgeber: Wiley-VCH
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- Sprache: Englisch
Cutting-edge information about materials, technologies, and mechanisms of printed electronics, and their applications for the smart packaging
Printed Electronics for Smart Packaging describes how and why to use printed electronic devices for application in smart packaging.
Written by a highly qualified academic, Printed Electronics for Smart Packaging covers sample topics such as:
- Applications of printed electronics, such as flexible screens, intelligent labels and packaging, interactive books and posters, and even upholstery
- Mechanisms of smart packaging, printing methods and integrated strategies, and functional inks and substrates for smart packaging
- Printed tracks for smart tags and IPES, printed optoelectronic devices and energy suppliers for smart packaging, and printed sensors and indicators
- Integrated printed electronics systems, and expert outlooks and perspectives on potential future directions for research and development in the field
A must-have resource for anyone to expand the knowledge of the latest developments for intelligent packaging, Printed Electronics for Smart Packaging is an essential read for not just related academics but also various intersecting industries and professionals due to the importance of packaging in all market sectors.
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Seitenzahl: 598
Veröffentlichungsjahr: 2025
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Author Biography
Preface
1 Introduction of Printed Electronics and Smart Packaging
1.1 Introduction
1.2 PE Technologies
1.3 Flexible PE Devices
1.4 PE for Smart Packaging
1.5 Content and Structure of This Book
References
2 Mechanisms and Strategies of Smart Packaging
2.1 Introduction
2.2 Active Packaging
2.3 Intelligent Packaging
2.4 Why You Need to Use PE?
References
3 Printing Methods and Integrated Strategies
3.1 Introduction
3.2 Conductive Mechanism of Printed Electronic Inks
3.3 Manufactural Process of PE Devices
3.4 Postprinting Process
3.5 Techniques and Parameters for PE
References
4 Functional Inks and Substrates for Smart Packaging
4.1 Introduction
4.2 Conductive Inks and Pastes
4.3 Printable Semiconductors and Insulator Inks
4.4 Conventional Substrates for PE Devices and Smart Packaging
References
5 Printed Tracks for Smart Tags and Packaging
5.1 Introduction
5.2 Printed Tracks, Interconnected Circuits, and Printed Antennas
5.3 Printed Flexible Transparent Electrodes
5.4 Printed Stretchable Electrodes and Stretchable Interconnects
5.5 Printed Flexible Heaters for Self-heating Packaging
References
6 Printed Optoelectronic Devices and Energy Suppliers for Smart Packaging
6.1 Introduction
6.2 Printed Optoelectronic Devices
6.3 Printed Energy Devices for Smart Tags and IPES
References
7 Printed Sensors and Indicators
7.1 Introduction
7.2 Printed Force Sensors
7.3 Printed Temperature and Humidity Sensors
7.4 Printed Piezoelectric and Triboelectric Sensors
7.5 Printed Gas Sensors
7.6 Printed Time–Temperature/Gas/Freshness Indicators
References
8 Integrated Printed Electronics Systems
8.1 Introduction
8.2 Printed Multisensor Platform
8.3 Wireless Sensor Platforms
8.4 E-skin
8.5 Self-powered IPES
8.6 IPES Tags for Smart Packaging
References
9 Outlooks and Perspectives
9.1 Introduction
9.2 The Consensus of Smart Packaging
9.3 Printed Electronics Technology's Advantages in Manufacturing Smart Packaging Products
9.4 Application Scenarios-Driven Smart Packaging Implementation
References
Index
End User License Agreement
List of Tables
Chapter 7
Table 7.1 The sensing materials, substrates, and performance of pri...
List of Illustrations
Chapter 1
Figure 1.1 Schematic illustration of the printing electronics can ...
Figure 1.2 The fabrication methods and characteristics of metallic...
Figure 1.3 Printing methods have been applied to fabricate various...
Figure 1.4 Conceptual diagram of the application of wearable elect...
Figure 1.5 Smart tag for monitoring of foods. (a) Inkjet-printed m...
Figure 1.6 Schematic illustration of smart blister packaging.
Figure 1.7 Schematic illustration of application radio frequency i...
Figure 1.8 Schematic illustration of the main contents and structu...
Chapter 2
Figure 2.1 Packaging functions in product-centered and user-center...
Figure 2.2 Conventional forms of active packaging and intelligent ...
Figure 2.3 (a) Gas exchanges between products and its surrounding ...
Figure 2.4 Effects of postharvest ethylene accumulation and ethyle...
Figure 2.5 Schematic operating mode of a colorimetric freshness in...
Figure 2.6 Schematic diagram of the phase-change transition of pha...
Figure 2.7 Schematic illustration of developed indicators or senso...
Figure 2.8 Color change in freshness indicators used to monitor th...
Figure 2.9 The schematic diagram of the time–temperature integrato...
Figure 2.10 The photographs of printed image of diacetylene-2 (DA...
Figure 2.11 Schematic illustration of sensor system and input–out...
Figure 2.12 Schematic illustration of mainly mechanical propertie...
Figure 2.13 Different types of flexible temperature sensors.
Figure 2.14 Different types of flexible temperature sensors. (a) ...
Figure 2.15 Schematic illustration of typical screen-printed elec...
Figure 2.16 Opportunities of biosensors for smart food packaging....
Figure 2.17 Schematic demonstration of accuracy and precision. Th...
Figure 2.18 Conceptual framework: drivers to integrated packaging...
Chapter 3
Figure 3.1 Conventional printed electronics technologies (R2R deno...
Figure 3.2 Schematic illustration of screen-printing process.
Figure 3.3 The structure parameters of screen mesh.
Figure 3.4 Schematic illustration of a rotary screen printing (cro...
Figure 3.5 Scanning electron microscopy images of the flat screen-...
Figure 3.6 (a) Photograph of stretchable printed tracks and patter...
Figure 3.7 Scheme illustration of ink transfer during the doctorin...
Figure 3.8 (a) Roll-to-roll gravure printing method to integrate s...
Figure 3.9 Schematic illustration of gravure offset printing proce...
Figure 3.10 (a) Schematic demonstration of reverse offset printin...
Figure 3.11 (a, b) Schematic illustration of flexographic technol...
Figure 3.12 Conventional inkjet printing methods: (a) piezoelectr...
Figure 3.13 The schematic illustration of fabrication process (a,...
Figure 3.14 (a–g) Scanning electron microscope images of the surf...
Figure 3.15 (a) Schematic illustration and photos of printed temp...
Figure 3.16 Resolution and throughput for various printing techno...
Chapter 4
Figure 4.1 Atomic structure of typical 2 D materials and correspon...
Figure 4.2 (a) Photograph of conventional Ag paste and (b) photogr...
Figure 4.3 Schematic demonstration of the synthesis of Ag nanopart...
Figure 4.4 (a) Schematic illustration of the built-in sintering me...
Figure 4.5 (a–c) Schematic illustration of the formulation of vege...
Figure 4.6 Scheme illustration of preparation antioxidant Cu paste...
Figure 4.7 (a) The sintering mechanism of dewetting behavior in Cu...
Figure 4.8 (a) Schematic demonstration the designed liquid metal p...
Figure 4.9 (a) Schematic illustration the composition and printing...
Figure 4.10 (a) Scheme illustration of the surface functional str...
Figure 4.11 Screen printing of carbon nanotubes/Ag composite ink ...
Figure 4.12 (a) Schematic illustration of the formulation process...
Figure 4.13 Schematic illustration of the fabrication process and...
Figure 4.14 (a) Schematic illustration of synthesis and decomposi...
Figure 4.15 (a) The chemical structure of poly(3,4-ethylenedioxyt...
Figure 4.16 (a) Different patterns fabrication using screen-print...
Figure 4.17 (a) Schematic demonstration of the liquid-phase exfol...
Figure 4.18 Schematic demonstration and photographs of double-sho...
Figure 4.19 Food packaging evolution since ancient time till date...
Figure 4.20 Schematic illustration of the contact angle (a) and t...
Chapter 5
Figure 5.1 Schematic illustration of printed tracks (including the...
Figure 5.2 (a) The resistance of Ag nanoparticles (AgNPs) and Cu n...
Figure 5.3 (a) Layout and photograph of the electrochromic display...
Figure 5.4 Manufacturing process and applications of flexible radi...
Figure 5.5 Scanning electron microscope (SEM) images of hexagonal ...
Figure 5.6 The thickness and shrinkage ratio (a), stress–strain cu...
Figure 5.7 Various designs of engineered geometries for stretchabl...
Figure 5.8 (a) Schematic demonstration of the printed flexible hea...
Figure 5.9 (a–c) Photographs of a printed flexible heater (PFH)-ba...
Chapter 6
Figure 6.1 Schematic illustration of a flexible electronic system ...
Figure 6.2 (a) Schematic illustration of the device structure and ...
Figure 6.3 Schematic illustration of the general structure of a th...
Figure 6.4 Smart pharmaceutical packaging solutions designed by Ge...
Figure 6.5 (a, b) Schematic illustration of the conventional multi...
Figure 6.6 Photos of patterned organic PFSCs.
Figure 6.7 (a) The process of roll-to-roll gravure printing for th...
Figure 6.8 Schematic illustration of the classic structure of supe...
Figure 6.9 (a) Schematic illustration of synthesis process of Mn-d...
Figure 6.10 Schematic illustration of various functions have been...
Figure 6.11 Schematic illustration of developing strategy of prin...
Figure 6.12 Schematic illustration and photographs of fabrication...
Figure 6.13 (a, b) The mechanical-electrochemical performance of ...
Figure 6.14 (a–d) Schematic illustration of the preparation proce...
Figure 6.15 (a) Schematic illustration of the layer-by-layer prin...
Figure 6.16 The process of preparing printed triboelectric nanoge...
Figure 6.17 (a, b) Schematic diagram and photos of the all-printe...
Figure 6.18 Printed self-powered visual sensing system. (a–c) Sch...
Chapter 7
Figure 7.1 The main challenges facing flexible sensors in the near...
Figure 7.2 (a) The conventional structure of printed resistive str...
Figure 7.3 Printed strain sensors for tamper-evident packaging. (a...
Figure 7.4 The device structure and photograph of a classical prin...
Figure 7.5 (a) Schematic illustration and fabrication process of p...
Figure 7.6 The sensing performance (Δ
C
versus time, a; Δ
C
versus r...
Figure 7.7 Schematic demonstration of roll-to-roll (R2R) printing ...
Figure 7.8 Design layouts and schematic demonstration of the wirel...
Figure 7.9 (a) The structure of conventional printed gas sensor (P...
Figure 7.10 (a) The preparing process of printed gas sensor (PGS)...
Figure 7.11 Schematic demonstration of the structure (a) and fabr...
Figure 7.12 Schematic diagram of the printed gas indicator (PGI) ...
Figure 7.13 (a, b) Schematic diagram of the circuit of the self-h...
Chapter 8
Figure 8.1 Schematic illustration of the integrated printed electr...
Figure 8.2 Schematic illustration of the (a) single-side, (b) doub...
Figure 8.3 Schematic demonstration of the signal processing proces...
Figure 8.4 (a) Preparation process of dual-mode sensor, and the st...
Figure 8.5 (a–c) Schematic demonstration and basic working princip...
Figure 8.6 (a) Photography of 4 × 4 strain sensor array and the ma...
Figure 8.7 (a) Using a prototype of a flexible temperature-sensing...
Figure 8.8 (a) Scheme illustration of the MXene-based fully printe...
Figure 8.9 Few example applications where e-skin is needed to enab...
Figure 8.10 The preparation procedures and photographs of the han...
Figure 8.11 (a) Schematic demonstration of the preparation proces...
Figure 8.12 Schematic illustration of the conventional elements a...
Figure 8.13 Schematic illustration of the conventional elements a...
Figure 8.14 (a) Schematic illustration of an IPES label and its f...
Chapter 9
Figure 9.1 Smart packaging can solve many challenges faced by trad...
Guide
Cover
Table of Contents
Title Page
Copyright
Author Biography
Preface
Begin Reading
Index
End User License Agreement
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Printed Electronics for Smart Packaging
Wei Wu
Author
Prof. Wei WuWuhan UniversityWuchang DistrictWuhan, 430072China
Cover Image: © Wei Wu
Library of Congress Card No.: applied for
British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library.
Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at <http://dnb.d-nb.de>.
Print ISBN: 978-3-527-35116-9ePDF ISBN: 978-3-527-84003-8ePub ISBN: 978-3-527-84004-5Obook ISBN: 978-3-527-84005-2
© 2026 WILEY-VCH GmbH, Boschstraße 12, 69469 Weinheim, Germany
All rights reserved (including those of translation into other languages, text and data mining and training of artificial technologies or similar technologies). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.
The manufacturer's authorized representative according to the EU General Product Safety Regulation is WILEY-VCH GmbH, Boschstr. 12, 69469 Weinheim, Germany, e-mail: [email protected].
In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions.
While the publisher and the authors have used their best efforts in preparing this work, including a review of the content of the work, neither the publisher nor the authors make any representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
Author Biography
Wei Wu received his BS degree and MS degrees from Hunan University of Technology in 2005 and 2008, respectively, and PhD degree from Wuhan University in 2011 (supervised by Prof. Changzhong Jiang). He then joined the group of Prof. Daiwen Pang at Wuhan University (2011) and Prof. V. A. L. Roy at City University of Hong Kong (2014) as a postdoctoral fellow. Currently, he is a full professor at the School of Physics and Technology, Wuhan University. He received the State Scientific Innovation and Pioneer Award in 2023, the 15th Bi Sheng Award of Printing Technology in 2019, the STAM Best Paper Award in 2017, and the Hong Kong Scholars Award in 2014. He has published over 100 papers, which have received over 15 000 citations. His research interests include the synthesis and application of printable functional materials, printed electronics and smart packaging, wearable electronics, and flexible electronic systems.
Preface
Packaging technology is constantly developing and innovating, and currently focuses on three major directions: green packaging, safe packaging, and smart packaging. I often wonder how traditional printing technology and industry can be transformed and upgraded, and whether mature printing technology can be used to manufacture flexible electronic devices. The rapid development of printed electronics technology has given the answer. In addition, the packaging manufacturing process cannot be separated from the deep involvement of traditional printing technology. Is it possible to introduce printed electronics technology into the packaging manufacturing process to realize the manufacturing of intelligent packaging?
The deep integration of printed electronics technology and smart packaging has brought disruptive innovations to the traditional packaging industry. Printed electronics technology integrates electronic components such as conductive inks and semiconductor materials into flexible substrates (such as paper and plastic films, which are most commonly used in packaging manufacturing) through printing processes, enabling smart packaging to break through the rigid limitations of traditional electronic devices and achieve lightweight, low-cost, and large-scale production. Smart packaging enabled by this technology can integrate intelligent modules such as temperature sensors, RFID tags, and flexible displays, so that the packaging has active perception and information transmission functions such as real-time monitoring (such as food freshness), dynamic interaction (such as AR scanning), and logistics tracking. The combination of the two not only increases the added value of the product but also realizes green manufacturing through roll-to-roll printing technology and promotes the transformation of packaging from passive containers to smart IoT terminals in the fields of medicine, logistics, consumer electronics, etc.
We can imagine this scenario, the rapid development of artificial intelligence (AI) and Internet of Things (IoT) technologies will inject dynamic data processing and decision-making capabilities into smart packaging integrated with printed electronic smart labels, pushing it from the “perception layer” to the “cognition layer”. AI algorithms can evaluate the status of goods (such as the stability of active ingredients in drugs) in real time by analyzing environmental data such as temperature, humidity, and light collected by flexible sensors in printed electronic labels, and use cloud models to predict shelf life or risk thresholds, triggering the electronic ink screen on the label to issue an early warning. This integration enables printed electronic labels to evolve from static information carriers to intelligent nodes with autonomous analysis and adaptive feedback capabilities, reshaping the packaging value chain in consumer, medical, and other fields. Smart packaging has become one end of IoT, which will tell us more non-printed graphic information and further enhance brand awareness. Smart packaging is connected to mobile phones and other terminals, making products safer and more reliable.
I completed the writing of this book independently, combining the latest research progress in printed electronics technology and smart packaging technology, hoping to systematically analyze the technical core and industrial ecology of smart packaging from an interdisciplinary perspective (including materials science, printing engineering, and electronic technology). Readers will not only be able to master the core technical principles of printed electronics and smart packaging, but also understand how temperature-sensitive labels can dynamically display the freshness of food, or how electronic ink can achieve self-updating tracking information in logistics. This will inspire readers to think about the business logic and social value of the implementation of smart packaging technology.
Finally, I would like to thank my team at Wuhan University for their support and help during the writing process. This book is dedicated to my daughter, Luoqi Wu, and my son, Shurui Wu. The writing process reduced the time I had to spend with them. I thank them for their understanding.
June 2025
Prof. Dr. Wei Wu
Wuhan University
1Introduction of Printed Electronics and Smart Packaging
1.1 Introduction
Smart packaging is a common solution to improve packaging value and functions, originating from the intersection of multidisciplinary fields and having distinct interdisciplinary characteristics. Smart packaging involves many research directions and application fields, including front-end knowledge of packaging design, and material science, printed technology, wireless communication technology, Internet of Things (IoT) technology, and so forth, as well as the basic knowledge of traditional packaging engineering.
The current research on smart packaging mainly focuses on two aspects: active packaging and smart packaging. The former mainly conveys and monitors information on products with life, such as packaging that uses time–temperature indicators (TTIs) labels. The latter uses various electronic technologies to provide an indication of status or convey other information about the product. Smart packaging has huge potential to improve product safety, quality, and traceability, as well as convenience for consumers.
In recent years, the safety of packaged contents in the logistics process has received extensive attention, especially the logistics and transportation of some valuable products. Monitoring the status of packaged products in the logistics process has become a challenge, and a large number of new technologies have been developed, adopted, and applied to traditional packaging, such as radio frequency identification (RFID) technology, infrared induction technology, global positioning system (GPS), and so forth. But it is noteworthy that these technologies have not been effectively integrated with packaging. Because of this, it is possible to solve these problems if we can combine packaging design and these electronic devices can be directly printed on the surface of packaging products during the graphic information printing process. Using traditional packaging-printing technology to manufacture thin-film electronic devices on packaging will also greatly reduce the production cost of smart packaging and promote its rapid development. As a highly interdisciplinary innovation field, printed electronics (PE) shows great breakthrough potential in promoting the development of ubiquitous electronic products and the innovation of traditional packaging technology [1].
1.2 PE Technologies
1.2.1 What Is PE Technologies?
Traditional printing technology is a very mature, fast, and efficient graphic information reproduction technology, and ink plays a very critical factor in it. As early as the 1980s, when organic conductors and organic semiconductor materials were discovered, people saw the hope that future electronic circuits might be fabricated by traditional printing technology. Because organic materials can generally be prepared in solution form, they have the typical characteristics of printing inks. It is hoped that by printing organic conductors and semiconducting inks, transistors in electronic devices can be fabricated and complex electronic systems can be constructed. However, among organic electronic materials, only a large class of organic small molecule materials have good electronic properties, and these organic small molecule materials must be prepared by vacuum evaporation to prepare electronic devices. The charge transport properties (charge mobility) of polymer organic electronic materials suitable for printing are always an order of magnitude worse than those of organic small molecule materials.
In recent years, PE has begun to develop rapidly, mainly because various inorganic micro-/nano-materials have been successfully transformed into functional inks and applied in the field of PE. Inorganic materials also have much higher charge mobilities than organic electronic materials [2–4]. Some inorganic nanomaterials (nanoparticles, nanowires, nanotubes, etc.) can be easily made into inks and then patterned using traditional printing methods [5–7]. The properties of micro-/nano-materials themselves endow these patterns with charge transport, dielectric, or optoelectronic properties to form various semiconductor, optoelectronic, and energy devices.
In this regard, PE becomes an emerging process technology that applies traditional printing methods to the manufacture of electronic circuits and complex multilayer electronic devices, requiring to formulate different functional materials into printing inks and deposit them onto various flexible or rigid substrates using traditional printing principles.
1.2.2 Why Should PE Technologies Be Developed?
High throughput and low cost
The printing area and printing speed of the traditional printing technology are very amazing, and the use of this technology to manufacture electronic devices will significantly reduce the manufacturing cost of the device. For example, gravure printing is a widely used roll-to-roll (R2R) technology that can rapidly manufacture high-resolution printed patterns at speeds of more than 150 m/min (determined by the length of the transmission distance between the printing units of the printing press), and these printed patterns are engraved as a discrete cavity into a rotary printing cylinder. The maximum printing area of screen printing can reach 300 cm × 400 cm. Therefore, PE technology can greatly improve production efficiency, simplify production processes, and reduce production costs.
Figure 1.1 Schematic illustration of the printing electronics can be fabricated by roll-to-roll printing press and in-lined with other functional units, such as drying, coating, assembly, folding, and so forth.
PE technology is directly connected with flexible electronics and R2R technology (Figure 1.1), and the goal is to make various functional electronic devices like those meant for printing newspapers. This is unthinkable for traditional circuit board and complex electronic device manufacturing processes. Moreover, PE substrates are diverse, including plastic, paper, fabric, and so forth. These substrates can be flexibly selected and can also be performed in parallel.
Additive process
PE manufacturing is an additive manufacturing process that generally does not require vacuum environmental conditions, but only requires printing functional inks where needed, which is an extremely material-saving manufacturing method [8]. As shown in Figure 1.2, the traditional photolithography involves a complex multistep process, including photoresist coating, mask exposure, development, and chemical etching. During the process, a lot of vacuum treatments are involved, which is time-consuming and requires a lot of expensive equipment. It belongs to a technology that first deposits and then removes unnecessary parts. Obviously, PE is a simplified process and material-saving technology. The development of flexible electronic devices is very rapid, and PE can realize circuit and device fabrication on curved substrates, which is also a very big advantage.
Figure 1.2 The fabrication methods and characteristics of metallic patterns by tradition lithography technology and printed electronic technology.
Figure 1.3 Printing methods have been applied to fabricate various types of electronic devices, which can also be directly integrated on flexible substrates by printing methods.
Integration and customization
The pursuit of foldable and flexible consumer electronic products continues to stimulate innovations in materials and manufacturing technologies. Different functional thin-film electronic devices are integrated on substrates and used to realize various functional applications. These devices also often need to be endowed with higher mechanical durability and stretchability and the ability to measure a variety of complex sensations over large areas. Indeed, many electronic components and interconnect circuits can be integrated and printed, such as sensors, batteries, passive devices, active devices, display units, and the like (Figure 1.3). Recently, some new printable functional materials and manufacturing routes to realize the fabrication of multifunctional electronic skins with mechanical compatibility have been developed, which requires the integration of numerous sensors and data processing and signal transmission electronics [9]. The printing method can be used for the manufacture of customized electronic devices, especially the digital inkjet, for which PE technology will be more convenient.
1.3 Flexible PE Devices
The scale of the consumer electronics market continues to expand, and people's needs and concerns are gradually changing to the bendable and flexible electronic devices. The manufacturing and development of flexible electronic devices have also received a lot of attention, which refer to electronic devices that can still work under a certain range of deformation (bending, folding, torsion, compression, or tension) [10]. Flexible electronics is an emerging electronic technology, which mainly manufactures electronic devices on flexible/stretchable substrates or provides flexible mechanical properties through device structure design. Similar to traditional integrated circuit (IC) technology, the manufacturing process is the driving forces for the development of flexible electronics, and the difficulty is achieving high-throughput, large-area, and low-cost fabrication of small-size electronic devices. Over the past four decades, thin-film flexible electronics in their various forms have underpinned much of the technological innovations in display, sensor, communication, and energy storage and conversion [11].
Texas Instruments invented the IC in 1958, and Intel Corporation invented the world's first commercial microprocessor 4004 in 1971. The two major technologies have promoted the rapid development of information technology, and microelectronics has always followed Moore's Law. Over the past half century, the scale of integration of microelectronic chips has grown by more than a billion times. In 2021, Apple released the new A15 bionic processor, which uses Taiwan Semiconductor Manufacturing Company, Ltd (TSMC)'s 5 nm process and integrates nearly 15 billion transistors. The core of microelectronics technology lies in the manufacture of chips. Microelectronic chips are ubiquitous in our lives, and it is this tiny but extremely important device that makes people's lives more and more intelligent and convenient. However, the traditional microelectronics technology manufacturing process is complicated and generally requires the selection of high-purity rigid substrates and harsh vacuum environments, making it difficult to realize the manufacture of flexible electronic devices.
The development of flexible electronics is one of the main directions of modern electronic information technology, and the form of some traditional electronic devices will also be completely changed, which will also lead to a change in the rigid impression of human beings on electronic products. For example, foldable, rollable, and flexible displays will change the presentation form of existing pictures and movies and make consumer electronic products such as mobile phones and TVs more novel and lightweight. The demand for flexible and wearable electronic products is very strong in the field of consumer electronics and customized medical care (Figure 1.4), and achieving low-cost manufacturing of flexible electronic products becomes the key. In this case, PE is a strong candidate due to its own smart manufacturing and low-cost attributes. The development of PE technology is not to replace traditional microelectronics technology, but to complement it, and can play a role in flexible electronics technology, wearable electronics technology, and smart packaging.
In recent years, the development of artificial intelligence technology has promoted the precision, intelligence, and efficiency of speech recognition, mechanical control, and economic policy decision-making. Flexible electronics is the basic support of artificial intelligence and will lead and expand the application of artificial intelligence technology in more fields. Flexible electronics have the advantages of thinness, lower power consumption, better biocompatibility, and tunable mechanical performance. The constructed health monitoring device can generally be applied to the joints where the human body often moves and does not affect sports and daily life. Smart wearable devices can wirelessly connect application software and networks to realize the combination of remote office and leisure and can also realize mind control technology based on physiological electrical monitoring, IoTs, and artificial intelligence technology. Implantable flexible electronic devices offer new treatments for complex diseases such as Parkinson's, epilepsy, and depression.
Figure 1.4 Conceptual diagram of the application of wearable electronics in smart sensing technologies, human–machine interfaces and health monitoring, interconnecting daily activities with facilities, devices, and mobile terminals.
Source: [12]/John Wiley & Sons/CC BY 4.0.
Flexible electronics can integrate cutting-edge technologies such as intelligent materials, sensors, information transmission, and processing and improve the intelligence level of related equipment and systems. The use of printing methods is the main way to reduce the manufacturing cost of flexible electronic devices. In-depth research in the field of flexible PE is a new engine driving comprehensive innovation and development. Printed flexible electronics is a subversive science and technology generated on the basis of a high degree of interdisciplinary integration. It is expected to break through the inherent limitations of classic silicon-based electronics and can be used for the design and integration of devices in the post-Moore era, energy revolution, medical technology reform, and so forth. The development of flexible PE devices become an important strategic opportunity for independent innovation to lead future electronic industrial development.
1.4 PE for Smart Packaging
Exquisite packaging is inseparable from packaging structure design and high-quality printing. Packaging and printing is an important means and approach to increase the added value of commodities, enhance commodity competitiveness, and develop markets. With Heidelberg and KBA, two of the world's largest packaging and printing equipment manufacturers, fully transforming into digital and intelligent direction, it marks that the packaging and printing industry has started a journey to fully enter the era of Industry 4.0. The use of printing methods to manufacture electronic devices on traditional packaging surfaces is expected to bring new functions to packaging and add more value to products. PE manufactures many electronic devices such as printed batteries for powering small systems [13–15], simple digital logic processing circuits for data processing [16–18], and physical or chemical sensors for data acquisition [19–22]. All these electronic devices can construct intelligent system on the surface of tradition packaging. Higher performance can be achieved with printed hybrid electronics [23]. Therefore, smart packaging based on PE technology will bring great changes to many packaging application scenarios.
1.4.1 Food Packaging
Foodborne illnesses are usually contagious or toxic and are caused by bacteria, virus, parasite, or chemicals entering the body through contaminated water or foods [24]. Food packaging safety is an important part of ensuring food safety. In fact, food packaging is an integral part of food manufacturing systems. It protects food from biological, chemical, and physical damage during the circulation process from the factory to the consumer. Food packaging can also have the function of maintaining the stable quality of the food itself, facilitating the eating and identification of food, attracting the image of consumption, and having value other than material cost. To a large extent, food packaging has become an integral part of food, which will directly or indirectly affect food quality [25]. Not only should modern food packaging focus on the development, research, and application of new packaging materials, but it also urgently needs to use PE technology to add higher technological content to promote the development and intelligence of packaging technology.
In addition to the fundamental role of protecting products from unwanted biological, chemical, and physical damage and keeping products clean, smart packaging system has a great potential for enhancing the shelf life and safety of food products [27]. As shown in Figure 1.5, the use of PE technology to manufacture smart tags with sensors and apply them to food packaging can greatly improve food safety monitoring and early warning capabilities. There are three types of smart labels (smart indicators, sensor-based labels and intelligent tags), one of which is a label with diagnostic or detection functions, mainly including TTIs, freshness indicators, oxygen indicators, carbon dioxide indicators, packaging leakage labels, and so forth. Various sensor-based labels have also been developed and used in food packaging, including oxygen sensors, gas sensors, biosensors, and the like. The core difference between sensors and indicators lies in their detection capabilities: sensors can accurately and quantitatively detect the target analyte in the package based on the response signal, while indicators only have qualitative or semi-quantitative analysis functions, which are mainly used to determine the presence or absence of the target analyte or the approximate concentration range. The intelligent tags often use the information technology, mainly including radio frequency identification tags (RFID), antitheft electronic surveillance tags, electromagnetic identification tags, and so forth. But in fact, these types of label technologies can be mixed through the design of the label structure and function, which further promotes the interaction of packaging safety information.
Figure 1.5 Smart tag for monitoring of foods. (a) Inkjet-printed multisensory platform. (b) A smart temperature-sensing label consisting of memory, display, and wireless communication unit.
Source: [26]/with permission of John Wiley & Sons.
1.4.2 Drug Packaging
Pharmaceutical packaging is an integral part of medicines and has a significant impact on the quality and safety of medicines. In recent years, with the diversification of drug types, the form of pharmaceutical packaging has also changed from single to diversified. The emphasis on drug quality and safety has been continuously strengthened, the supervision has become increasingly strict, and pharmaceutical packaging enterprises are facing greater challenges. Drug packaging is supposed to provide information to doctors, pharmacies, and patients, and the amount of information is growing. In addition to the information that must be provided by laws and regulations, users also want to receive information to help them take their medicines correctly.
As shown in Figure 1.6, with wireless technologies such as RFID/NFC and Bluetooth, new communication channels can be established with patients while their behavioral data are analyzed. Thus, smart pharmaceutical packaging can realize some important interactions, such as reminding them of their upcoming medication schedules and providing important reminders for medication [28]. Doctors can also use the app to inform patients about their personal doses and easily adjust those doses when their health improves, avoiding the drug-overdose epidemic. Prototypes of drug packages with integrated e-paper display already exist [29]. Through display devices and acoustic and visual signals integrated on the drug packaging, drug packaging can convey information such as reminding patients to take their medicines in time and purchase new medicines in time. Smart pharmaceutical packaging can also avoid drug sorting errors to the greatest extent and has great advantages in drug storage and sorting in large medical institutions [30]. Obviously, these electronic components can be manufactured by PE technologies, and low-cost smart packaging systems can play a huge role in monitoring drug dosage and serve for smart medical applications.
Figure 1.6 Schematic illustration of smart blister packaging.
1.4.3 Smart Logistics and Supply Chain
Problems such as ensuring the authenticity and reliability of packaged products, ensuring whether the cold chain packaging products are really in a suitable environment during the entire process of transportation, and ensuring that the checked baggage in airport is no longer lost have opened up a lot of new opportunities for PE products and possibility. As shown in Figure 1.7, low-cost labels based on PE methods that can track goods in real time and enable verification of agreed transport parameters at any time also have huge benefits for building smart supply chains [31]. Intelligent packaging based on the IoTs and cloud computing has become the goal and direction of the development of intelligent logistics [32, 33]. In the logistics process, many carton packages are generally discarded after the goods are delivered, but as the amount and cost of carton boxes increase year by year, this method is neither environmentally friendly nor economical. In recent years, many food retailers and manufacturers have asked to switch to plastic recyclable pallets or boxes as a way to be environmentally friendly and reduce costs. Nonetheless, customer demands face new challenges, such as pallets that are often not recycled efficiently or pallets that are transferred to third parties to prove ownership. If smart labels are applied to these fields, these problems will also be solved.
Figure 1.7 Schematic illustration of application radio frequency identification tag technologies in supply chain enables error-free, real-time efficiency and visibility throughout your operations (end-to-end asset visibility and authentication).
With the rapid development of e-commerce, online shopping is becoming more and more popular, resulting in massive express packaging. Express service connects hundreds of industries and thousands of households and is an indispensable part of modern production and life. The number of express parcels worldwide has exceeded 100 billion. This has made the express delivery a labor-intensive industry, many of which are repetitive actions, such as the sorter of a delivery company scanning barcodes. In fact, traditional express barcodes can be completely replaced by smart labels. For example, smart labels are attached to the express package of a container. When passing through the transfer station, the data information on the label can be automatically sent to the data concentrator. As long as these data information is further transmitted to the automation equipment with set parameters, the scanning device can automatically identify the properties and destination of the goods, and the sorting equipment can work without scanning the codes one by one.
1.5 Content and Structure of This Book
The mission of PE is to serve the development of flexible electronics in the electronic information industry, and it is oriented to the research on the frontier basic issues of flexible electronics in organic display, energy devices, life and health, and national defense and military industries. PE involves printing engineering, electronic and information technology, materials science, and the like. The intersection of knowledge fields covers the knowledge system of key materials of PE, processing technology, flexible electronic devices, and so forth.
This book is divided into nine chapters in all. In terms of content, each chapter is relatively independent, but also has a certain logical connection, as shown in Figure 1.8. Chapter 1 clarifies the definition of PE, why PE should be developed, and how PE can be applied in smart packaging. Chapter 2 mainly demonstrates the definition and existence forms of intelligent packaging, why it is necessary to develop intelligent packaging, and the main means and trends of intelligent packaging development. Chapters 3 and 4 focus on the most conventional PE manufacturing methods and functional inks and substrate materials used in PE and smart packaging, focusing on how printing methods can be used to enable the manufacture of electronic devices and integrate with smart packaging. Before realizing the fabrication of electronic devices, electrodes, tracks, and circuits are the basic elements that make up electronic devices, and Chapter 5 will provide an overview of these basic elements in conjunction with some common PE devices in smart packaging. Chapters 6 and 7 will focus on PE devices commonly found in smart packaging and describe how printing methods can be used to fabricate devices, including optoelectronics, sensors, indicators, and power-supplying devices. In the practical application of smart packaging, different types of PE devices will be integrated onto the surface of packaging materials or attached to the packaging in the form of smart labels/tags, all of which need to realize the construction of integrated printed electronic systems (IPES). Chapter 8 will focus on demonstrating the recent progress of IPES. In Chapter 9, a systematic summary of the book will be provided and an outlook on the development trends of PE technology involved in smart packaging will be discussed.
Figure 1.8 Schematic illustration of the main contents and structure of this book.
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2Mechanisms and Strategies of Smart Packaging
2.1 Introduction
Packaging is a general term referring to various containers, materials, and their supporting auxiliary materials used in the circulation process of commodities to achieve the purpose of protecting product integrity, facilitating storage and transportation, and promoting market sales. Generally, the function of packaging mainly has two aspects: one is the natural function, that is, it protects the commodity, and the other is the social function, that is, it acts as a mediator for the commodity; in other words it introduces the commodity to the consumers and attracts the consumers, achieving the purpose of expanding sales to occupy the market. Practicality in packaging design is always the core position, which needs to follow ergonomic structural design, and ultimately constitute a packaging that is convenient and fast for product quality and demand.
In the field of packaging, the products and users are concerned about the functions of packaging and are not the same, especially in the three aspects of protection, utility, and communication, as shown in Figure 2.1 [1, 2]. For the three main functions of packaging, intelligent packaging refers to the use of innovative packaging materials, structural designs, and forms to enhance and ensure the quality of goods and their safety during circulation, or use information collection, management, control, and processing technologies to optimize the packaging systems or supply chain of products, or use electronic information and Internet of Things (IoT) technologies to deliver more nonprinted graphic information to consumers. With the rapid development of printed electronics (PE), wearable electronics, wireless communication and cloud data technologies, and the integration of solutions, packaging systems are becoming smarter and can provide more information to product manufacturers and consumers [3]. Especially in the field of food packaging, the limitations of traditional packaging have also become increasingly prominent, unable to meet the functional requirements of consumers, which are driven from the demand of natural products and the increasing expansion and diversification of supply chain for feeding a growing global population [4].
In the field of intelligent packaging, current research mainly focuses on two aspects: active packaging and intelligent packaging [5]. As shown in Figure 2.2, the conventional forms of active packaging include moisture regulators, ethylene removal systems, CO2 scavengers, antimicrobial active packaging (ACP), antioxidant and oxygen scavengers, phase-change materials (PCMs)–based active packaging, the purpose of all these active packaging being used to maintain or extend the quality and shelf life of products. And the intelligent packaging often uses the indicators, sensors, data carriers, and information display technologies to demonstrate the additional information, and the purpose is using some electronic information technology to interact with the real-time status of packaging products and supply chains.
Figure 2.1 Packaging functions in product-centered and user-centered routes.
Figure 2.2 Conventional forms of active packaging and intelligent packaging.
There are also many connections between active packaging and smart packaging. The development purpose of some smart packaging is to use the principle of active packaging to solve the problems of active packaging. For example, in fruit/vegetables storage packaging, fresh fruits and vegetables maintain their continuous respiration activity after harvesting, absorbing oxygen and producing carbon dioxide, water, and heat. If the oxygen supply is insufficient, anaerobic metabolism or anaerobic respiration will occur, and fruits and vegetables will lose their flavor and aroma. If the water vapor produced by the respiration of fruits and vegetables accumulates into free water, it will provide favorable conditions for the reproduction of spoilage microorganisms and greatly shorten the shelf life. If a new type of packaging material can be used to create modified atmosphere conditions conducive to the storage of fruits and vegetables, an active packaging will be formed; if an indicator or sensor can be used to monitor the changes in gas and moisture inside the packaging, a smart packaging will be formed.
2.2 Active Packaging
2.2.1 Moisture Regulators
Humidity control is very important for packaging, especially for some food packaging that need to maintain freshness such as vegetables, fruits, and meat. In addition, humidity is also a very critical factor for some paper-based packaging materials or paper-based products, which is very likely to affect the mechanical properties of those materials. For example, the fresh-keeping method of modified atmosphere packaging (MAP) combined with refrigeration is the most commonly used strategy for fruits and vegetables, but it is difficult to adjust the humidity in the package while using MAP to adjust the content of O2 and CO2. Because in MAP preservation of fruits and vegetables, plastic film packaging bags with certain air permeability are generally selected for ensuring the ideal O2 and CO2 content in the bag. And such packaging bags generally have low moisture permeability, which is easy to cause the water vapor in the packaging to be saturated. When the storage environment temperature fluctuates, even to a slight extent, the water vapor will condense into water droplets, which will lead to the growth of harmful microorganisms and accelerate the decay of fruits and vegetables [6–9].
Obviously, in order to avoid the production of various harmful microorganisms, the control of humidity is very important, and this problem is generally solved by the design of packaging structure or the introduction of materials with humidity control function [10, 11]. The research on humidity control materials used in packaging began with inorganic materials, and later developed into organic materials [12]. In order to further improve the performance of moisture absorption and moisture conduction, organic/inorganic composite materials have become the main research topic in recent times [13–16]. Such materials can make use of the ultra-high water vapor absorption capacity of organic polymer materials to make up for the shortcomings of inorganic materials that are easy to deliquescence and low moisture capacity and use the porous structure of inorganic materials to improve the moisture conductivity. This mechanism uses the synergistic effect of two different materials to achieve humidity control inside the package. In some metal products or electronic products, humidity control materials–based packaging are also required to prevent rust and corrosion of the metal. Packaging of moisture-sensitive products is an area of ongoing research, and the different indicators or sensors that can also be used to monitor humidity changes have turned into research topics in intelligent packaging.
Figure 2.3 (a) Gas exchanges between products and its surrounding atmospheres in a permeable package. Schematic illustration of passive modified atmosphere packaging (MAP) (b) and active MAP (c).
2.2.2 Modified Atmosphere Packaging
MAP is a commonly used active packaging form in food packaging, which can be widely used to preserve the freshness of various foods, prolong the shelf life of food, and enhance the value of food. The gas environment in the MAP can be actively regulated by using absorbent substances (such as scavenger) or releasing substances (such as emitter) to dynamically adjust the concentration of gases or vapors, thereby achieving active regulation of the atmosphere inside the package [17]. Nitrogen, oxygen, and carbon dioxide are often used in MAP, while ethylene is the main component that needs to be removed in MAP.
In MAP, it is necessary to fully consider the air permeability characteristics of packaging materials, and select a suitable single gas or mixed gas in combination with the specific needs of the items to be packaged. MAPs can be classified into passive and active types according to the way the internal atmosphere changes. As shown in Figure 2.3, the main disadvantage of the passive MAP is that reaching the desired atmosphere is very slow. This can sometimes generate uncontrolled gas levels, causing further damage to the food. Active MAPs typically first create a vacuum environment and then add the desired gas mixture to the package. In contrast to passive MAP, active MAP is actually instantaneous and occurs at the beginning of storage. The atmosphere should then remain almost the same, provided proper barrier material is used and there are no leakages [18]. Therefore, MAP is an atmospheric modification that relies on the interaction between the natural processes of product respiration and gas exchanges through packaging [19].
MAP is the replacement of air in a pack with a single gas or mixture of gases, and various gases are used in MAP, such as carbon dioxide (CO2), oxygen (O2), nitrogen (N2), argon (Ar), nitrous oxide (N2O), hydrogen (H2), and the like [20–22]. High concentration of CO2 can inhibit the growth and reproduction of aerobic bacteria and other microorganisms (e.g., aerobic bacteria, mold), prolong the stagnation period and exponential growth period of microorganisms, and play the role of anticorrosion and antimold. It is noteworthy that CO2 dissolves in water and fat in food, thereby lowering the pH of the food, and CO2 can also penetrate bio-membranes, resulting in changes in permeabilities and functions. Oxygen inhibits the growth and reproduction of most anaerobic spoilage bacteria, maintains the color of fresh meat, and maintains the oxygen-rich respiration and freshness of fruits and vegetables. Nitrogen is an ideal inert gas. In food packaging, it neither reacts chemically with food nor is it absorbed by food. Its function is to effectively reduce the oxygen concentration inside the packaging, significantly inhibit the growth and reproduction of microorganisms, and delay the oxidation, deterioration, and corruption of food, thereby ensuring that the freshness of food is maintained for a long time. Nitrogen-filled MAP is also good at preventing food extrusion and maintaining food geometry, which is rapidly replacing traditional vacuum packaging. MAP can also be filled with a variety of mixed gases, using the advantages of each gas. Based on the specific category of food, preservation requirements, and characteristics of packaging materials, the ratio of gas components is adjusted scientifically to achieve the best preservation effect and quality assurance of packaged food, realize good nutrient content preservation, and achieve long-term freshness preservation.
In the MAP system, several factors determine how the atmosphere changes inside the package, including the air permeability of the packaging materials, the surface area of the package, and the weight and breathing rate of the fruit and vegetable [23]. The respiration rate of the products and the gas permeability of the storage films are two fundamental kinetic processes considered when designing a packaging system [24]. Various packaging materials are used in MAP, including various common plastic films such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and the like [25–27]. Foods are dynamic systems with very limited shelf lives. Therefore, packaging requirements differ from those associated with inert products [28]. For some common fruits, vegetables, and meat products, conventional MAPs can already meet the demand. However, for some very expensive foods or special products, it may also be necessary to accurately understand the precise changes in the atmosphere in the packaging, which requires the intervention of intelligent packaging technology.
2.2.3 Ethylene Scavengers
Low-temperature storage methods can usually reduce the respiration of fruits and inhibit the production of ethylene to prolong the shelf life of fruits. However, some fruits will soften and turn black, which is irreversible and unavoidable (Figure 2.4). Endogenous ethylene biosynthesis in fresh produces can accelerate its ripening process, cause fresh fruits and vegetables overripe, or lead to rapid mildew/decay, reducing the postharvest life, shortening shelf life, and causing losses under conducive conditions [30]. The sensitivity of fruits and vegetables to ethylene is closely related to their type and maturity degree.
An effective way to regulate the production or reduction of ethylene in packaging is to use ethylene scavengers. Active packaging with ethylene scavengers is a cutting-edge system currently used in the food industry [31]. Commonly used ethylene scavengers mainly involve three mechanisms, namely, to directly destroy its molecular structure by using strong oxidants, such as potassium permanganate (K2MnO4) [32, 33]; to reduce ethylene concentration by physical adsorption, such as clay, zeolite, activated carbon, and the like [34, 35]; and to realize the decomposition of ethylene molecules driven by light with the help of semiconductor photocatalytic materials, such as titanium dioxide (TiO2) [36–38]. There are also ways to use some materials to inhibit the production of ethylene and decrease ethylene biosynthesis [39–41]. Combining these ethylene suppression and removal technologies in packaging is an effective way to enhance the shelf life of fruits and vegetables [42].
Figure 2.4 Effects of postharvest ethylene accumulation and ethylene scavenger on the ripening and shelf life of fresh fruits.
Source: [29]/with permission of Springer Nature.
Ethylene can be visualized using chemical principles and applied to packaging for indication. For example, the starting probe technology based on fluorescently labeled Grubbs catalyst provides a highly sensitive quantitative analysis method for ethylene detection [43]. As the market demand for high-quality fruits continues to expand, the detection standards for parts per billion (ppb)–level ethylene during postharvest processing are becoming increasingly stringent [44]. Ideally, developing a sensor that can accurately identify and measure the concentration of ethylene molecules would be of great benefit to extending the shelf life of fruits and vegetables.
2.2.4 Antimicrobial Active Packaging
At present, ACPs have become a popular packaging method in the market, and it is one of the most promising applications of food active packaging technology. The natural bacteriostatic agents, antioxidants, and natural extracts are used alone or combined with packaging materials and vacuuming packaging technology or MAP to form a new packaging system. The ACP materials have to extend the lag phase and reduce the growth rate of microorganisms for extending shelf life and maintaining product quality and safety [45]. In ACP, antibacterial materials with bacteriostatic and
