Life Cycle Assessment of Paper Based Printed Circuits

Qiansu Wan

Licentiate Thesis in Information and Communication Technology School of Information and Communication Technology KTH Royal Institute of Technology Stockholm, Sweden 2017

KTH School of Information and Communication Technology TRITA-ICT 2017:24 SE-164 40 Kista ISBN 978-91-7729-636-2 SWEDEN

Akademisk avhandling som med tillstånd av Kungl Tekniska högskolan framlägges till offentlig granskning för avläggande av licentiatexamen i informations- och kommunikationsteknik måndagen den 29 januari 2018 klockan 10:00 i Ka-Sal C (Sal Sven-Olof Öhrvik), Electrum, Kungl Tekniska högskolan, Kistagången 16, Kista.

Tryck: Universitetsservice US AB

Abstract

Printed circuit boards have been massively manufactured and wildly used in all kinds of electronic devices during people’s daily life for more than thirty years since the last century. As a highly integrated device mainly consists of silicon base, an etched copper layer and other soldered components, massive production of printed circuit boards are considered to be environmentally unfriendly due to the wet chemical manufacturing mode and lack of recycling ability. On the other hand, the newly invented ink jet printing technology enables cost-effective manufacturing of flexible, thin and disposable electrical devices, which avoid acid etching process and lead to less toxic emissions into the environment. It is important to consider life cycle analysis for quantitative environmental impact evaluation and comparison of both printed circuit boards and printed electronics to enhance the sustainability of a new technology with product design and development. This thesis first reviews the current approaches to conventional and modern printing methods, as well as the state-of-the-art analysis of sustainability and environmental assessment methodologies. In the second part, a typical ink jet printed electronic device is introduced (an active flexible cable for wearable electrocardiogram monitoring). This active cable is designed for the interconnection between bio electrodes and central medical devices for bio signal transmission. As the active cable consists of five different metal transmission traces which are formed by printing conductive ink onto paper substrates, different shielding methods are investigated to ensure high quality bio signal transmission. Specifically, the results prove that passive shielding methods can significantly decrease the cross talk between different transmission traces, enabling the transmitting of bio signals for wearable ECG monitoring. This research also explores environmental issues related to printed electronics. For the full life cycle of printed electronics, we focused not only on quantitative environmental emissions to air, fresh water, sea and industrial soil, but also on resource consumption and impacts analysis. Finally, comparative environmental performance evaluation of traditional cables and ink jet printed active cables are made to examine the environmental impact and sustainability of both technologies, and the results show the strengths and weaknesses of each technology by analysis and assessment. Keywords: Printed Electronics, Environment, PCB, Life Cycle assessment, Emissions

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Sammanfattning

Tryckta kretskort har massproducerats och har använts flitigt i all sorts elektronik de senaste decennierna. Eftersom högintegrerade komponenter består såväl av kisel som etsade kopparlager och lödda komponenter så är massproduktionen av kretskorten inte ansedd som miljövänlig beroende på en våtkemi-baserad tillverkningsteknologi och begränsade återvinningsmöjligheter. Å andra sidan undviker den nyligen utvecklade bläckstråleteknologin för kostnadseffektiv produktion av tunna och flexibla engångs-komponenter våtetsprocesser och leder till mindre omfattande giftiga utsläpp i naturen. Det är därför viktigt att utföra livscykelanalyser för att utvärdera den kvantitativa miljöpåverkan för såväl traditionellt tryckta kretskort som bläckstråletryckt elektronik samt att kunna bidra till en ökad hållbarhet för den nya tekniken genom produktdesign och utveckling. Denna avhandling granskar nuvarande metoder för konventionell och modern tryckteknik, samt ger en ”state-of-the-art”-analys av deras hållbarhet och miljöpåverkan. Därefter införs, som exempel på en typisk jetstråletryckt elektronisk komponent, aktiva kablar för bärbar elektrokardiogram (ECG)-övervakning. Denna aktiva kabel är designad för att signalmässigt sammanlänka bioelektroderna med de biomedicinska komponenterna. Eftersom den aktiva kabeln består av fem olika metalänkar som tillverkats med tryckt ledande bläck på papperssubstrat så undersöks olika skärmningsmetoder för att säkerställa hög kvalitet i signalöverföringen. Specifikt visar mätresultaten att passiv skärmning märkbart kan minska överhörning mellan olika transmissionsledningar vilket möjliggör insamling och transmission av bio-data för bärbar ECG-övervakning. Avhandlingen undersöker också miljöproblem relaterade till tryckt elektronik. För en fullständig livscykelanalys har vi inte enbart fokuserat på kvantitativa miljöutsläpp till luft, färskvatten och hav utan också på resursförbrukning och påverkansanalys. Slutligen jämförs miljöprestandan för traditionella kablar med bläckstråletryckta kablar för att utreda miljöpåverkan och hållbarhet för bägge teknikerna. Analysen och utvärderingen visar därmed på styrkor och svagheter i bägge fallen. Keywords: Tryckt elektronik, Miljö, Polyklorerade bifenyler, Livscykelanalys, Utsläpp

Acknowledgements

First, I am especially grateful to my supervisor Prof. Lirong Zheng, for his sense of responsibility, enlightening guidance and incredible patience of my licentiate study and research, as well as the opportunity he provided to me to join the iPack center. I owe my profound attitude to my previous second supervisor Dr. Qiang Chen, for his fruitful advices and encourages all through these years. I sincerely appreciate to Dr. Geng Yang, for his instructive suggestion and support on my first conference and journal paper.

Special thanks to Prof. Hannu Tenhunen and Dr. Rajeev Kumar Kanth from Turku University, Finland for their wise inspiration and harmonious collaboration in previous research projects.

I would also like to thank all my colleagues and friends at KTH along this journey, Dr. Jian Chen, Dr. Ana Lopez Cabezas, Dr. Botao Shao, Dr. Awet Yemane Weldezion, Dr.Li Xie, Dr. Liang Rong, Dr. Chuanying Zhai, Dr.Qin Zhou and Pei Liu.

I want to express my deepest and warmest appreciation to my parents for their endless love and support in my life and this academic career. Last, but not the least, my heartfelt gratitude goes to my wife Jie Gao, thank you, for everything.

Qiansu Wan Stockholm, 2017

Contents

Contents ...... vii

List of Figures ...... ix

List of Tables ...... x

List of Publications ...... xi Papers included in the thesis: ...... xi Papers not included in the thesis: ...... xi

List of Acronyms ...... xii

Chapter 1 Introduction ...... 1 1.1 Motivation ...... 1 1.2 Thesis Aim and Objectives ...... 2 1.3 Contributions and Thesis Organization ...... 3 Chapter 2 ...... 4 Chapter 3 ...... 4 Chapter 4 ...... 5 Chapter 5 ...... 5

Chapter 2 Life Cycle Assessment ...... 7 2.1 Environmental Life Cycle Assessment ...... 7 2.1.1 Goal and scope definition: ...... 8 2.1.2 Inventory analysis ...... 8 2.1.3 Impact assessment ...... 9 2.1.4 Improvement Assessment ...... 11 2.2 Variants of Life Cycle Assessment ...... 11 Cradle to grave ...... 11 Cradle to gate ...... 11 Cradle to cradle ...... 11 Gate-to-gate ...... 12 Well-to-wheel ...... 12 vii

Economic input–output life cycle assessmen ...... 12 Ecologically based LCA ...... 12 2.3 LCA Software and Database ...... 12 2.4 Critical issues with LCA ...... 13 2.5 LCA Related Issues with Printed Electronics ...... 13 2.6 Summary ...... 15

Chapter 3 Printed Electronics ...... 17 3.1 Background ...... 17 3.2 Inkjet Printed Flexible Cable ...... 19 3.2.1 Conception ...... 19 3.2.2 Flexible Cable Printing and Feasibility Test ...... 19 3.2.3 Electrical Perfirmance Test ...... 22 3.3 Related LCI data collection ...... 22 3.4 Summary ...... 23

Chapter 4 Quantitative Environmental Evaluation ...... 25 4.1 Study Scope ...... 25 4.2 LCI Computation ...... 26 4.3 Results presentation ...... 28 4.3.1 Results of Inkjet Printing Technology ...... 29 4.3.2 Results of conventional ECG cables ...... 30 4.4 Comparison Analysis and Assessment ...... 30 4.5 Sensitivity Analysis ...... 31 4.6 Summary ...... 31

Chapter 5 Conclusion and Future Work ...... 33 5.1 Thesis Summary ...... 33 5.2 Future Work ...... 33

Bibliography ...... 35

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List of Figures

Figure 1.1 Global Printed Electronics Market Size and Forecast ...... 2 Figure 1.2 Paper based Printed Flexible Cable (a) and its Cross Section (b) ...... 3 Figure 2. 1 Illustration of Life Cycle Assessment through Products’ Life Cycle Stages ...... 8 Figure 2.2 Illustration of the phases of an LCA (ISO, 1997) ...... 9 Figure 3.1 Complementariness of printing technology and conventional electronics Courtesy: Institute of Print and Media Technology, Chemnitz University of Technology...... 17 Figure 3.2 Application for ECG monitoring (a) and its illustration (b)...... 18 Figure 3.3 (a) DMP 2800 Printer. (b) Dropping Ink from nozzles. (c) Printed drops and metal trace on Substrate...... 19 Figure 3. 4 Printed Samples for Active and Passive Shielding Test ...... 20 Figure 3. 5 System boundary of paper based flexible cable ...... 21 Figure 4.1 (a) Printed Flexible Cable on Testing Board (b) Traditional ECG Cable on Humanbody ...... 25 Figure 4.2 Procedural Flow Diagram for Life Cycle Analyzing ...... 26 Figure 4.3 Plan for Printed ECG Cables ...... 27 Figure 4.4 Plan for traditional ECG cable ...... 28 Figure 4.5 Total emission of printed flexible cable ...... 28 Figure 4.6 Emission to air from Printed ECG cable ...... 29 Figure 4.7 Total Emission of Traditional ECG cable ...... 30

List of Tables

Table 2.1 Commonly used life cycle impact categories (SAIC 2006) ...... 10 Table 3.1 Comparison of common printing techniques [13] ...... 18 Table 3.2 Induced voltage on victim line when transmitting a 20V pulse voltage with rise edge of 40 nanoseconds on the aggressive line ...... 20 Table 4.1 Process Interpretation of Printed ECG ...... 27 Table 4.2 Process Interpretation for Traditional ECG ...... 27

List of Publications

Papers included in the thesis:

i. Qiansu Wan, Rajeev Kumar Kanth, Geng Yang, Qiang Chen, Lirong Zheng, "Environmental Impacts Analysis for Inkjet Printed Paper-based Bio-patch", in Journal of Multidisciplinary Engineering Science and Technology , 2015, Page(s): 837-847

ii. Rajeev Kumar Kanth; Qiansu Wan, Pasi Liljeberg, Aulis Tuominen, Lirong Zheng, Hannu Tenhunen, "Investigation and Evaluation of Life Cycle Assessment of Printed Electronics and its Environmental Impacts Analysis". in Proceedings of NEXT 2010 Conference, Page(s), 52 – 67 iii. Qiansu Wan, Geng Yang, Qiang Chen, Lirong Zheng, “Electrical performance of inkjet printed flexible cable for ECG monitoring”, in Electrical Performance of Electronic Packaging and Systems (EPEPS), 2011 IEEE 20th Conference on EPEPS, San Jose, USA, Page(s), 231 – 234 iv. Geng Yang, Q. Wan, L.- R. Zheng, “Bio-Chip ASIC and Printed Flexible Cable on Paper Substrate for Wearable Healthcare Applications,” in the 4th International Symposium on Applied Sciences in Biomedical and Communication Technologies (ISABEL 2011), Spain, 2011. Page(s), 76 – 80

v. Qiansu Wan, Zhuo Zou, Lirong Zheng, “Life Cycle Assessment of Paper Based Printed Interconnections for ECG Monitoring”, in European Journal of Engineering Research and Science Vol. 2, 2017, Page(s), 65 - 70

Papers not included in the thesis:

i. Rajeev Kumar Kanth, Qiansu Wan, Harish Kumar, Pasi Liljeberg, Qiang Chen, Lirong Zheng, Hannu Tenhunen " Evaluating Sustainability, Environment Assessment and Toxic Emissions in Life Cycle Stages of Printed Antenna", in Journal Publications for Elsevier Procedia Engineering and Science Direct, 2011, Page(s), 1-7

ii. Rajeev Kumar Kanth, Qiansu Wan, Waqar Ahmad, Harish Kumar, Pasi Liljeberg, Li Rong Zheng, Hannu Tenhunen, "Insight into the Requirements of Self-aware, Adaptive and Reliable Embedded Sub-systems of Satellite Spacecraft", in Conference Proceedings of International Conference on Pervasive and Embedded Computing and Communication Systems, 1, Science and Technology Publications Lda(SCiTePress), 2012. Page(s), 603 - 608

List of Acronyms

CAGR Compound Annual Growth Rate DMP Dimatix Materials Printer ECG Electrocardiogram ECOLCA Ecologically based LCA EDCW European Data Center on Waste EPD Environmental Product Declarations EIOLCA Economic input–output LCA ICT Information and Communication Technology ISO International Organization for Standardization LCA Life Cycle Assessment LCI Life Cycle Inventory LCIA Life Cycle Improvement Assessment NPS-JL Nano-Particle Silver Jetable Low-temperature ink PAH Polycyclic Aromatic Hydrocarbons PCB Printed Circuit Board PE Printed Electronics PWR Power R2R Roll-to-Roll REF Reference SAIC Scientific Applications International Corporation SCL Serial Clock SDA Serial Data WEEE Waste Electrical and Electronic Equipment

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Chapter 1

Introduction

1.1 Motivation

With impending climate change and increasing environmental degradation, environmental and sustainability-related issues are gaining considerable attention all over the world, of which both energy consumption and environmental emissions are the core focus. In the meanwhile, an unignored truth is that ICT industry has already consumed 4.7% of the total produced electricity worldwide [1], also the European Data Center on Waste (EDCW) points out that waste electrical and electronic equipment (WEEE) are currently considered to be one of the fastest growing waste streams in the EU, growing at 3-5 % per year [2]. It is extremely important to look into the environmental issues related to electronic system production comprehensively. On the other hand, novel printed electronics technology based on additive processes are now considered as the most environmental friendly method of electronic device manufacturing. According to the Global Printed Electronics Market Report, market forecasts of printed electronics is predicted to reach $19 billion by 2024; growing at a CAGR (Compound Annual Growth Rate) of 22.6% from 2016 to 2024 [3], as shown in Fig. 1.1 [3]. Therefore, there is a strong need to further enhance its environmental performance to make it more in line with the “Green ICT” definition.

Since over 80% of all product-related environmental impact can be influenced during the early design phase [4], as potentially the best and most commonly used environment analysis tool [5], Life Cycle Assessment [6, 7, 8] should be conducted on environment impact evaluation and improvement assessment of

printed electronics.

Figure 1.1 Global Printed Electronics Market Size and Forecast

In order to implement life cycle assessment for printed electronics, a paper based inkjet printed flexible cable for ECG monitoring is chosen as the research target due to the following advantages:  Heart desease is now the most common cause of death among aging people in the EU. Thus there is a strong need for the wearable medical/healthcare devices for ECG monitoring such as printed flexible cable.  Comparing to trantional ECG cables, inkjet printed ECG cable is not only disposable, flexible, easy to use and comfortable to patients, but also can solve problems like structure failure, cable tangling and so on.  As a typical printed electronics, printed flexible cable is potentially more environmental friendly.

1.2 Thesis Aim and Objectives

The main aim of this licentiate thesis is to explore the LCA of paper based inkjet printed electronics for a full range of environmental effect quantification and focus on its comparison to traditional electric system production. However, it has been realized that there is no solid structural implementation of LCA of flexible electronics existing yet, nor its related environmental data as well. The challenge here is to identify the limitations of printed electronics to fulfill the

2 environmental requirements. In this case, the main objectives of this thesis are:

 To propose and print a paper based inkjet printed flexible cable for wearable ECG monitoring system not only for feasibility testing, but also for investigation into printed electronic for LCI modelling and data collection. Fig 1.2 shows the flexible cable and its cross section.

 To map and increase understanding of LCA methodology.

 To conduct LCA for both inkjet printed flexible and traditional ECG cable for parallel comparison.

 To assess printed electronics design strategies from a life cycle perspective.

 To establish improved assessment to enable “Green” design for printed electronics and inkjet printing technology.

(a)

25 ㎛ (b) Silver trace

Figure 1.2 Paper based Printed Flexible Cable (a) and its Cross Section (b)

1.3 Contributions and Thesis Organization

This thesis is organized in four chapters as follows:

Chapter 2

Detailed LCA theory is briefly introduced in this chapter. For the aspect of LCA application of a new technology, variants of LCA technologies are described. Related environmental issues with printed electronics are also discussed.

Contributions:

The literature survey regarding LCA is carried out. LCI modelling and evaluation have also been established in a related LCA project.

Included papers:

Qiansu Wan, Rajeev Kumar Kanth, Geng Yang, Qiang Chen, Lirong Zheng, "Environmental Impacts Analysis for Inkjet Printed Paper-based Bio-patch", in Journal of Multidisciplinary Engineering Science and Technology , 2015, Page(s): 837-847

Rajeev Kumar Kanth; Qiansu Wan, Pasi Liljeberg, Aulis Tuominen, Lirong Zheng, Hannu Tenhunen, "Investigation and Evaluation of Life Cycle Assessment of Printed Electronics and its Environmental Impacts Analysis". Proceedings of NEXT 2010 Conference, Page(s) 52 – 67

Chapter 3

In chapter 3, the present trends of printed electronics and inkjet printing are introduced and an overview of the fabrication process on paper based inkjet printed cable for wearable ECG monitoring system is given. Feasibility test for paper based ECG cable has been described with both active and passive shielding methods. The results show that ECG signal transimission is available on paper based inkjet printed ECG cables.

Contributions:

First, different kinds of printed samples were designed with EDA tools and fabricated from printing phase to sintering phase. Second, feasibility test related experiment design and operations were accomplished, as well as LCI data collection at the same time.

Included papers:

Qiansu Wan, Geng Yang, Qiang Chen, Lirong Zheng, “Electrical performance of inkjet printed flexible cable for ECG monitoring”, Electrical Performance of Electronic Packaging and Systems (EPEPS), 2011 IEEE 20th Conference on EPEPS, San Jose, USA, Page(s): 231 – 234

Geng Yang, Q. Wan, L.- R. Zheng, “Bio-Chip ASIC and Printed Flexible Cable on Paper Substrate for Wearable Healthcare Applications,” in the 4th International Symposium on Applied Sciences in Biomedical and Communication Technologies (ISABEL 2011), Spain, 2011. Page(s), 76 – 80

Chapter 4

Chapter 4 investigated the life cycle assessment and environmental impacts of paper based printed flexible ECG cable with a parallel comparison to traditional ECG cables. The results show that printed flexible ECG cable causes much less harmful and hazardous impacts to the environment. After the inventory data analysis we reached the conclusion that inkjet printed electronics are more environmental friendly.

Contributions:

A general operational framework for the LCA implementation of printed electronics is developed. The case study is focused on parallel comparison with different technologies that target some applications.

Included papers:

Qiansu Wan, Zhuo Zou, Lirong Zheng, “Life Cycle Assessment of Paper Based Printed Interconnections for ECG Monitoring”, in European Journal of Engineering Research and Science Vol. 2, 2017, Page(s): 65 - 70

Chapter 5

This chapter concludes the thesis and discusses further work.

Chapter 2

Life Cycle Assessment

2.1 Environmental Life Cycle Assessment

The International Organization for Standardization (ISO) 14040-series [33] defines Life Cycle Assessment (LCA) as “a systematic set of procedures for compiling and examining the inputs and outputs of materials and energy and the associated environmental impacts directly attributable to the functioning of a product or service system throughout its life cycle” (ISO 14040) [34, 35, 36]. Fig. 2.1 shows the full life cycle assessment system boundaries and all four life cycle stages of a target product. Through the identification and quantification of energy and substance use, as well as the release of waste into the environment [37], the LCA evaluation is an attempt to determine all the resulting environmental impacts, and provides an opportunity to assess and improve the targeted product design for sustainability.

A full life cycle assessment includes the following four components as shown in Fig. 2.2:  Goal and scope definition  Inventory analysis  Impact assessment  Interpretation (also known as Improvement assessment)

Inputs Outputs

Water effluens Raw materials acquisition

Airborn emissions Energy Manufacturing Solid waste

Raw Use / Re-use / materials Maintenance Other enviromental releases

Recycle / Waste Usable products management

System boundary Figure 2. 1 Illustration of Life Cycle Assessment through Products’ Life Cycle Stages

2.1.1 Goal and scope definition:

Goal and scope definition are the first steps in defining the rational for conducting the LCA and its general intent [38], as well as specifying the product systems and data categories to be studied (ISO 10140 [33]). Before an LCA is begun, the purpose for the activity must be defined to determine the system boundaries. Typically LCA studies are performed in response to specific questions, of which the nature determines the goal and scope of the study [39]. In this research, due to the complexity of electronics system productions involving infinite numbers of categories for different materials and manufacturing processes, printed electronic technology is compared with traditional PCB technology, which acts as a reference and parallel for the initial investigation.

2.1.2 Inventory analysis

Life Cycle Inventory Analysis [40, 41] is an objective, data-based process for quantifying energy and raw material requirements, air emissions, waterborne effluents, solid waste, and other environmental releases throughout the life cycle of a product (ISO 14141). As the second procedure of LCA system, inventory analysis is the most important and time consuming phase. That is, LCI input and

8 output data are fundamental to all LCA algorithms, analysis and assessments, of which the data collection process is always too tedious [42] because of the lack of consistent standards (i.e. different environment related legislations and policies in different countries) and sources (i.e. different data value for a certain material/process from different organizations such as industry, academic area or government).

Figure 2.2 Illustration of the phases of an LCA (ISO, 1997)

2.1.3 Impact assessment

The Life Cycle Impact Assessment (LCIA) is a technical, quantitative or semi- quantitative process to characterize and assess the effects of the environmental loadings identified in the inventory component [43]. The assessment should address both ecological and human health considerations, as well as other effects such as habitat modification or noise pollution (ISO 14142 [33]). LCIA provides information for interpretation by following steps (SAIC 2006 [44]):

 Select the impact categories (as show in Table 2.1) to include indicators and models  Classification due to assignment of LCIA results  Characterization based on category indicator results  Data quality analysis  Normalization (optional)  Grouping (optional)  Weighting (optional)

Table 2.1 Commonly used life cycle impact categories (SAIC 2006) Impact Scale Examples of LCI Data Common Possible Description of Category (i.e. classification) Characterization Characterization Factor Factor

Global Global Carbon Dioxide (CO2) Global Warming Converts LCI data to Warming Nitrogen Dioxide (NO2) Potential carbon dioxide (CO2) Methane (CH4) equivalents. Chlorofluorocarbons (CFCs) Methyl Bromide (CH3Br)

Stratospheric Global Chlorofluorocarbons (CFCs) Ozone Depleting Converts LCI data to Ozone Hydrochlorofluorocarbons Potential trichlorofluoromethane Depletion (HCFCs) (CFC-11) equivalents. Halons Methyl Bromide (CH3Br) Acidification Regional Sulfur Oxides (SOx) Acidification Converts LCI data to Local Nitrogen Oxides (NOx) Potential hydrogen (H+) ion Hydrochloric Acid (HCL) equivalents. Hydrofluoric Acid (HF) Ammonia (NH4) Eutrophication Local Phosphate (PO4) Eutrophication Converts LCI data to Nitrogen Oxide (NO) Potential phosphate (PO4) Nitrogen Dioxide (NO2) equivalents. Ammonia (NH4) Photochemical Local Non-methane hydrocarbon Photochemical Converts LCI data to Smog (NMHC) Oxidant Creation ethane (C2H6) Potential equivalents.

Terrestrial Local Toxic chemicals with a reported LC50 Converts LC50 data to Toxicity lethal concentration to rodents equivalents; uses multi- media modeling, exposure pathways. Aquatic Local Toxic chemicals with a reported LC50 Converts LC50 data to Toxicity lethal concentration to fish equivalents; uses multi- media modeling, exposure pathways. Human Health Global Total releases to air, water, and LC50 Converts LC50 data to Regional soil. equivalents; uses multi- Local Media modeling, exposure pathways. Resource Global Quantity of minerals used Resource Depletion Converts LCI data to a Depletion Regional Quantity of fossil fuels used Potential ratio of quantity of Local resource used versus quantity of resource left in reserve. Land Use Global Quantity disposed of in a landfill Land Availability Converts mass of solid Regional or other land modifications waste into volume using Local an estimated density. Water Use Regional Water used or consumed Water Shortage Converts LCI data to a Local Potential ratio of quantity of water used versus quantity of resource left in reserve.

2.1.4 Improvement Assessment

Life Cycle Improvement assessment is a systematic evaluation of the needs and opportunities to reduce the environmental burden associated with energy and raw materials use and environmental release throughout the whole life cycle of the product, process or activity [45]. This assessment should include both quantitative and qualitative measures of improvements (ISO 14143) [33].

2.2 Variants of Life Cycle Assessment

Since the first LCA was established in the USA in the 1970’s, more than 40 years ago, there are now several commonly used LCA methods variants which are briefly discussed below:

Cradle to grave Cradle-to-grave is the full Life Cycle Assessment from manufacture ('cradle') to use phase and End-of-life phase ('grave') [46], and sometimes considered as the same as whole-life cost. That is, all the environmental inputs and outputs through product’s different life stages are included to explore product’s environmental performance. Thus it is always not possible to bring gradle to grave LCA into complex system productions due to its property on time consuming process and heavy LCI data demands.

Cradle to gate Cradle-to-gate is an assessment of a partial product life cycle from manufacture ('cradle') to the factory gate (i.e., before it is transported to the consumer) [47]. Cradle-to-gate assessments are sometimes the basis for environmental product declarations (EPD) (ISO 14025). In this sense, gradele to gate LCA is commonly chosen for novel technologies which are not ready for mass production stage. Here in this thesis work, a gradle to gate LCA has been carried out for inkjet printing technology in comparison with tranditional PCB technology.

Cradle to cradle Cradle-to-cradle [48] is a specific kind of cradle-to-grave assessment, where the consideration on end-of-life phase of the product is only gaining to the recycling process. The main method of cradle to cradle life cycle assessment is to determine the reuse portentiality and materials recycling ability of a product or activity for waste management.

Gate-to-gate Gate-to-gate is a partial LCA focusing on one value-added process in the entire production chain [49]. In other words, gate-to-gate life cycle assessment usually determines the environmental impacts/emissions of a single step/process in one of the production’s life cycle stage. Therefore it is possible to form a full LCA evaluation by compiling the results of Gate-to-Gate modules from different processes and life cycle stages.

Well-to-wheel Well-to-wheel is the specific LCA used for examining the efficiency of fuels used for road transportation phase in raw material preparation [50]. The analysis is often broken down into stages such as "well-to-station" and "station-to-wheel, or "well-to-tank" and "tank-to-wheel", and mostly used to assess the energy comsumption and emissions impacts throughout these stages [51] [52]. Hence well-to-wheel life cycle assessment is normally used in the area of transportation industry and logistics companies for efficiency use of fuels.

Economic input–output life cycle assessmen Economic input–output LCA (EIOLCA) involves use of aggregate sector-level data on determining how much environmental impact can be attributed to each sector of the economy, and how much each sector purchases from other sectors [53]. EIOLCA evaluation is based on the resource use and emissions released through out different products or industries within long supply chains. For instance, to assess an PCB based product, the effort should not only focus on the impacts at its own assembly process, but also impacts from the raw material extraction, power generation and component manufacturing, etc. Thus EIOLCA is commonly used on national strategy level, and not suitable for environmental impacts evaluation of a certain product.

Ecologically based LCA Ecologically based LCA [54] was developed by Ohio State University Center for resilience. Eco-LCA is a methodology that quantitatively takes into account regulating and supporting services during the life cycle of economic goods and products [55]. Comparing to conventional LCA, Eco-LCA is mainly focused on accounting methods of the biophysical/ecological resources use, which would indicate the role of resources in different life cycles.

2.3 LCA Software and Database

Environmental evaluation for life cycle analysis is heavily depended on LCI database for involving processes or activities throughout product’s life cycle stages. Hence it is sometimes too difficult to perform a full LCA which is data

12 intensive. To deal with the infinite amount of data from both input and output within the targeted system boundaries, computers and LCA softwares are used for data compilation, LCI modeling and results presentation. In this thesis work, GaBi database combined with openLCA, ecoinvent, and U.S. LCI are included because according to the market survey, GaBi from PE international is now taking the lead in close proximity to 60% market share and portentialy considered as the best product sustainability solution for life cycle assessment. GaBi [32] software mainly helps user within the following aspects:

 LCA design for environment  Eco-efficiency and Eco-design  Efficient value chains  designing and optimizing products and processes for cost reduction  Greenhouse gas accounting  Energy efficiency learning  Environmental risk management

2.4 Critical issues with LCA

The European Commission concluded that Life Cycle Assessments provides the best framework for assessing the potential environmental impact of products currently available, in its Communication on Integrated Product Policy (COM 2003-302) [56]. Even though LCA is still far from accomplishment for environment impact evaluation and assessment. There are some limitations and drawbacks to LCA that should be addressed and understood, which include:

 LCI Data limitation: not enough and proper data to cover the need for all materials and processes.  Uncertainties: LCA based on the compilation of a large number of parameters and scenarios, which are associated with assumptions and uncertainties.  Time consuming: too many methodologies and process involved for a full LCA.  Reliability: results heavily depend on the practitioners’ knowledge or skill on LCA.

2.5 LCA Related Issues with Printed Electronics

In comparison with traditional circuit manufacturing process, the foreground of

13 printed electronics is strong. Inkjet printing technology acts as an additive process to deposit the functional conductive materials regarding to the designed pattern, which allows the use of low-cost flexible substrate materials such as polymers and even paper [57]. On the other hand, traditional PCBs in manufacturing phase have to involve with wet chemical etching progress. Therefore, the general environmental aspects for printed electronics are briefly discussed as below:

• Toxic emission Compared with traditional electronic productions, a big advantage in printable electronics is the minimal usage of toxic chemicals involved [58]. With the avoidance of chemical acid usage for etching process in traditional electronics fabrication process, printed electronics provide environmental friendly potential for electronics devices manufacturing.

•Efficient use of materials One of the main environmental advantages of printed electronics is the efficient use of raw materials in the manufacturing phase [59]. The less materials in use, the less wastes would exist, as well as less energy would be consumed, which leads to more “Green” electronic device design and fabrications.

• Energy consumption Since inkjet printing technology prints the conductive ink directly on the substrate, printed electronics consume significantly less energy than traditional electrical productions, which cost a huge amount of energy in manufacturing phase due to involving with wet chemical progress for etching. However, printed electronics require additional sintering process after printing phase, which would cost extra energy in manufacturing phase.

• Life cycle length One of the problems with printed electronics compared to conventional PCBs is the short operating lifespan [60]. Most Printed electronics’ life cycle length is no longer than several thousand hours, but traditional PCBs usually could be used at least three years and even more than that in some case.

•Improvement of Recyclability The problem in recycling process for printed electronics is that products usually contain toxic substances which are hard to identify and decompose, leading to harmful waste [61]. Compared with traditional PCBs, the recyclability of printed electronics has a stronger foreground because it is possible to decrease the variety of materials [58] would be used for production. Moreover, in end-of-life phase after ink recycling, incineration is considered as an efficient solution to minimize

14 potential environmental impact for printed electronics.

2.6 Summary

In this chapter, the basic architecture of LCA theory was briefly introduced. For the aspect of LCA assessment of a new technology, the detailed procedure to calculate LCA is described. According to the published literature, there are several limitations and drawbacks of LCA. LCA issues related to printed electrics were also considered.

Chapter 3

Printed Electronics

3.1 Background

Printed electronics (PE) is a term that defines the printing of circuits on media such as paper and textiles, but also on a large number of potential media [9].

Figure 3.1 Complementariness of printing technology and conventional electronics Courtesy: Institute of Print and Media Technology, Chemnitz

University of Technology. The recent rapid development of PE technology is motivated by the promise of low-cost, high volume, high-throughput production of electronic components or devices which are lightweight and small, thin and flexible, inexpensive and disposable [10]. Compared to conventional silicon-based electronics [11], the unique nature of additive manufacturing process and selectable range of flexible substrates makes PE not only a substitute or competitor but also a lead with broad prospects for massive new applications in low-cost macroelectronics [12], which is visually shown in Fig. 3.1.

Table 3.1 Comparison of common printing techniques [13] Printing Print Resolution Print Speed Wet Film Technique [µm] [m/min] Thickness [µm] Flexographic 30-70 50-500 0.5-8 Gravure 20-75 20-1000 0.1-5 Offset 20-50 15-1000 0.5-2 Screen 50-100 10-100 3-100 Inkjet printing 20-50 1-100 0.3-20

With the long term development of flexible PE since the 1960s, several existing printing technologies such as flexographic, offset, gravure, screen, inkjet printing, etc [14] [15] have been applied to electronic systems for high volume Roll-to-Roll (R2R) fabrications. The comparison of these most common printing technologies as shown in Table 2.1 [13] which also lists some key parameters of each technology in terms of print resolution, print speed and wet film thickness. All printing technologies have their advantages and disadvantages [16, 17] and there is not a simple choice of printing technology existing for electronic systems.

Ports for bio-signal electrodes Bio-signal sensor REF

SCK

SHD

Flexible cable SDA

VCC (a) (b) Figure 3.2 Application for ECG monitoring (a) and its illustration (b).

Among all above printing technologies, inkjet printing provides the best quality of print resolution but lacks fast printing ability. By depositing functional ink onto a flexible substrate according to the patterned scale, inkjet printing is now

18 considered to be the most popular printing method [18, 19], which provides the driving force for change in electronic systems from the design through the manufacturing phases. Furthermore, as an additive non-contact process [20], inkjet printing technology eliminates the waste of material, which is environmental friendly and also provides great potential for Green ICT design.

3.2 Inkjet Printed Flexible Cable

3.2.1 Conception

The paper based flexible cable [21, 22, 23] is a new application for inkjet printing technology that has been applied to a wearable electrocardiogram (ECG) monitoring system. This flexible cable acts as the connection between bio-electric sensors and a central medical device such as a computer or electrocardiogram monitor [21], as shown in Fig 3.2 (a). The cable is composed of five metal traces [24, 25, 26]: the first metal line configured to deliver serial data from the sensor to the medical central device, the second metal trace configured to deliver a therapeutic voltage from the medical central device to the sensor, the third metal trace configured as a grounded shielding line, the fourth metal trace configured to transfer a bio-signal from the sensor to the medical central device, and the fifth metal trace configured to provide system power, and are named in terms of Ref, Sck, Shd, Sda and Vcc, respectively, as shown in Fig 3.2 (b).

(a) (b) (c) Figure 3.3 (a) DMP 2800 Printer. (b) Dropping Ink from nozzles. (c) Printed drops and metal trace on Substrate.

3.2.2 Flexible Cable Printing and Feasibility Test

In order to make sure that high quality ECG signals transmission is possible in

19 this flexible cable, different types of samples were printed through a DMP-2800 printer (Fujifilm Dimatix materials printer as shown in Fig 3.3 a). The printing process can be seen in Fig 3.3 (b) and (c) which show screen shots of ink dropping from the printing nozzles onto the paper substrate in different time and shapes. All samples were fabricated by printing Nano-Particle Silver Jetable Low- temperature ink (NPS-JL) on to the photo paper substrate for feasibility tests.

Active Shielding Sample with 1 mm clearance

Active Shielding Sample with 2 mm clearance

Passive Shielding Sample with 0.5 mm width shielding line

Passive Shielding Sample with 1 mm width shielding line

Figure 3. 4 Printed Samples for Active and Passive Shielding Test

The most critical challenge for fabricating the proposed flexible cable concerns both internal and external electromagnetic field interference between the parallel printed metal traces, especially when the ECG signal has an amplitude in the range of 1 to 5 mV and frequency contents from 0.5 Hz to 200 Hz [27], which is too sensitive for transmission over the printed trace. Therefore, both active shielding [28, 29] and passives shielding [30, 31] methods were tested with printed samples as shown in Fig 3.4.

Table 3.2 Induced voltage on victim line when transmitting a 20V pulse voltage with rise edge of 40 nanoseconds on the aggressive line Samples Spacing/ Induced Voltage on Victim Line Average Width (Unit: mV) (Unit:mV) Active1 1 mm 165 178 230 210 220 270 212 Active2 2 mm 140 156 168 129 170 165 155 Passive1 0.5 mm 32 38 40 36 50 45 40 Passive2 1 mm 19 28 21 26 25 30 25

While increasing and decreasing the value of clearance/width of the shield line for both active and passive shielding methods, the results listed in Table 3.2 show

20 that with active shielding method the average induced voltage is reduced to 155 mV from 212 mV by increasing the clearance between the victim/ aggressive line. With passive shielding method the average induced voltage is reduced to 25 mV from 40 mV by increasing the width of inserted shielding line. Accordingly, with the combination of both active and passive shielding methods, the induced voltage rate [32] decreased by 88%, which is efficient for ECG signal transmission.

Natural resources Energy

Raw Material

Conductive Ink Paper

Fabrication Process

Inkjet Printing Sintering

Paper based Flexible Cable

Recycling of Ink Waste Disposal and Paper

Emissions

Figure 3. 5 System boundary of paper based flexible cable

3.2.3 Electrical Perfirmance Test

The electrical performance measurement of the fabricated paper based flexible cable in frequency domain/ time domain reflection is performed with a wide bandwidth oscilloscope and a vector network analyzer. The results show that the purpose of ECG signal transmission with high quality on the flexible cable is obtained.

Return Loss Measurement: The return loss is around 30 dB in ECG signal’s working frequency range, which is ignorable for bio signal transmission. But with high frequencies (up to 200-900 MHz), the interface reflection from impedance matching would cause significant signal attenuation on transmitting line.

Signal Attenuation Measurement: When the flexible cable is connected with the central ECG device, observed results from the oscilloscope show that the ECG signal could be still received at far end while large signal attenuation ratio exists, whereas the maximum bandwith of the signal is around 150 Hz.

Time-domain Reflectometer: The results from time domain reflectometer measurement show that with 3.3 ns of signal transmitting time, the reflection is observed in 572.1 ps behind. Thus multiple refections is avoid for ECG signal transmission.

A more detailed description of the electrical performance of printed flexible cable is presented in Paper III & IV.

3.3 Related LCI data collection

Throughout the proposed printed flexible cable fabrication from design to feasibility test, the system boundary for Life Cycle Inventory (LCI) analysis is established as shown in Fig 3.5. Related LCI data categories is briefly listed as below:

 the energy usage on printing process with the Dimatix printer

 the energy usage on printing process with the computer connected to the printer

 the energy usage of the sintering process with the oven at 100 ℃ for 1 hour

 the raw conductive ink material used

 the raw photo papers material used

3.4 Summary

In this chapter, the background of printed electronics and inkjet printing technology was introduced. We have attempted to give an overview of the fabrication process using paper based inkjet printed cable for a wearable ECG monitoring system. The proposed flexible cable using both active and passive shielding methods can significantly decrease mutual crosstalk which enables ECG signal transmission. We have also explored the related issues with LCA methodology regarding this flexible cable.

Chapter 4

Quantitative Environmental Evaluation: A Case study involving Printed Flexible Cable

4.1 Study Scope

Printed electronics nowadays are gaining considerable attention due to its unique ability for “desktop manufacturing” of electronic devices and green ICT design. LCA was chosen to qualify the environment performance of printed electronics as it is the most commonly used systematic tool for environment evaluation.

(a) (b) Figure 4.1 (a) Printed Flexible Cable on Testing Board (b) Traditional ECG Cable on Humanbody

In order to implement LCA for printed electronics research, a case study was carried out for the fabricated printed flexible cable for ECG monitoring described in chapter 3. The method used was to compare printed electronics with conventional PCB technology. In this example, the study was based on the comparison between the environmental impact of paper based printed flexible cable and traditional ECG cable as shown in Fig 4.1.

LCA Plan

Supporting Instance Interpretation

Calculation Analysis

Figure 4.2 Procedural Flow Diagram for Life Cycle Analyzing

4.2 LCI Computation

Since inkjet printing for printed electronics is a new technology with barely reliable LCI data from research institutes or industry, the GaBi software was chosen for LCI compilations in this work for both technologies. The compilation process shown in Fig. 4.2. is based on the GaBi data base in combination with collected LCI data described in chapter 3. In the procedural flow diagram, the LCI computation is defined as:

 LCA plan is the compilation of the input of all function unit of a target within LCA system boundaries for life cycle modelling. Fig 4.3 shows the LCI plan for inkjet printed flexible cables.

 The flow is the connection between different processes with related LCI data.

 Process interpretation defines the input data value. The process interpretation of an inkjet printed cable is shown in Table 4.1, which indicates the input value of raw materials for 100,000 unit production.

 Supporting database is the combination of local database and incorporated LCI data.

 Process instance presents local process adjustments and settings need when the plan is finalized.

 Balance is the LCI data computation process leading to the final results.

Figure 4.3 Plan for Printed ECG Cables

Similarly, the plan and process interpretation for traditional ECG cable are both settled as shown in Fig 4.4 and Table 4.2, respectively.

Table 4.1 Process Interpretation of Printed ECG Flows Amount (kg) Units

Paper Substrates 750 100000

Conductive ink 180 100000

Table 4.2 Process Interpretation for Traditional ECG

Flows Amount (kg) Units

PVC 1560 100000

Copper Wire 9250 100000

Plastic Parts 1235 100000

9250kg

Copper Wire

1560kg

Traditional PVC ECG Cable

1235kg

Plastic

Figure 4.4 Plan for traditional ECG cable

4.3 Results presentation

This section focuses on the results obtained for both printed flexible cable and traditional ECG cable. The environmental impacts evaluation was carried out for different life cycle stages, and the conventional ECG cables were used as an important reference for comparison purposes.

Figure 4.5 Total emission of printed flexible cable

4.3.1 Results of Inkjet Printing Technology

For the production of 100000 inkjet printed flexible cables, Fig.4.5 shows the total emissions from inkjet printed ECG interconnection in the manufacturing phase. The dominant emission to the environment is to the air, which takes 98% of total emissions. Most of the remaining 2% of the emissions is to fresh water. Sea water receives the rest in microscale amounts which is less than 0.1% of total emissions. From input resources, it is noticed that paper substrates consume most of the renewable material resources which mainly consist of water and air. To the other side, consumed nonrenewable resources normally contain metal ore as majority.

Figure 4.6 Emission to air from Printed ECG cable

As shown in Fig.4.6, the printed flexible ECG cable produces harmful emissions to air mainly in the form of inorganic emissions, organic emissions, heavy metals to air, particles to air and radioactive emissions to air. The inorganic emission contains components such as ammonia, carbon dioxide, carbon monoxide and so on.

4.3.2 Results of conventional ECG cables

This section describes the analysis of environmental emissions for the production of 100000 conventional ECG Cables. For the production of 100000 normal ECG Cables, Fig.4.7 clearly shows the total environmental emissions in the manufacturing phase. The dominant emission to the environment is to the air. The data shows that 75.5% of emissions are to the air and 24% to fresh water.

Figure 4.7 Total Emission of Traditional ECG cable

Conventional ECG cables produce a large amount of harmful emissions to air mainly caused by inorganic emissions, organic emissions, heavy metals, and particles. The inorganic emissions are mostly composed of components such as ammonia, carbon dioxide, carbon monoxide. The other emissions to the air consist of materials such as heavy metals to air, group PAH to air and halogenated organic emissions to air. There are other emissions to the air such as organic emission, radioactive emission to air and particles to air. The amount of these emissions is negligible compared to the inorganic emissions.

4.4 Comparison Analysis and Assessment

According to the resuts from section 4.3, the total mass of emission from 100000 units of printed flexible cable is 7174 KG. At the mean while, the same amount of traditional ECG cables cause 1869550 KG waste to the environmental, which is in

30 close proximity to 260 times more than paper based inkjet printed ECG cables. On the other hand, to fabricate the same amount of each kind of ECG cables, inkjet printing technology costs 930 kg raw materials and tranditional ECG cable consumed 12045 kg raw materials in manufacturing phase. Thus we can conclude that inkjet printing technology saves 92% resource usage and reduces 95% emission to the environment. In addition, for both technologies, the major portion of hazardous emission is inorganic waste gas released to the air in different categories, and again inkjet printing technology releases ignorable amount of waste gas in comparison to traditional ECG cables.

With the comparison analysis for both inkjet printing technology and traditional ECG cables, the parallel gradle-to-gate life cycle assessment has been established. The simplified life cycle assessment framework implemtation for paper based printed circuits has been carried out. The case study from the fabrication of printed flexible cable to the examination of LCA evaluation not only fulfills the goal of insight into a novel technology for environmental impacts investigation, but also leads to further research scope on more complex paper based inkjet printing systems within full life cycle stages.

4.5 Sensitivity Analysis

First of all, since it is already realized that there is no enough solid LCI data for printed electronics, especially for the fuctional conductive ink. Secondly, some of the LCI data are from secondary sources or outdated open resources. Eventhough this situation does not change the overall conclusion of conducted research because a reference technology (i.e traditional ECG cable here) was chosen for parallel analysis in the same condition, and LCA analysis for novel technology always comes with unavoidable uncertainties.

4.6 Summary

In this chapter, LCA for both printed ECG cable and traditional ECG cable were established. The results show that printed ECG cable caused significantly less harmful emissions to the environment and need much less raw materials for fabrication compared to traditional ECG cables. In brief, technology wise printed flexible cable is more environmental friendly. More detailed discussion and comparisons are presented in Paper V.

Chapter 5

Conclusion and Future Work

5.1 Thesis Summary

This thesis has described the attempt to evaluate the feasibility of a paper based inkjet printed flexible cable for a wearable ECG monitoring system. It has also included a quantified investigation into the environment impact of the proposed inkjet printed ECG cable in comparison with traditional cables. The first stage of this work showed the feasibility test demonstrating that the printed ECG cable is capable of transmitting ECG signals while resisting both internal and external interferences. Following parallel LCA comparison results indicate a promising future for printed electronics in the Green ICT system.

All through the inkjet printing process to the fabricated sample, as well as the LCA theoretical study, we have explored a general framework for the LCA implementation for printed electronics. The study carried showed that inkjet printing technology is more environmental friendly.

5.2 Future Work

The results presented so far suggest several directions for the further work. First, for inkjet printing technology it is important to examine the environmental performance of different raw materials such as ink and substrate. It is indispensable to improve both the design phase of printed electronics and the LCA framework itself. Second, the ability to recycle printed electronics is a

33 challenging topic due to the short lifespan of devices that are considered to be disposable in contrast to traditional electronic devices that are normally required to last for years.

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