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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

TRITA-ICT 2017:24 ISBN 978-91-7729-636-2

KTH School of Information and Communication Technology

SE-164 40 Kista 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.

© Qiansu Wan, November 2017

Tryck: Universitetsservice US AB

iii

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

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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

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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

viii

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

ix

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

x

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

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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

xii

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

2

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

3

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.

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:

(a)

(b)25 ㎛

Silver trace

4

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:

5

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.

6

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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)

8

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

Raw materials acquisition

Manufacturing

Use / Re-use /

Maintenance

Recycle / Waste

management

System boundary

Inputs

Water effluens

Airborn emissions

Solid waste

Other enviromental releases

Usable products

Outputs

Energy

Raw

materials

9

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)

10

Table 2.1 Commonly used life cycle impact categories (SAIC 2006)

Impact Category

Scale Examples of LCI Data (i.e. classification)

Common Possible Characterization

Factor

Description of Characterization

Factor

Global Warming

Global Carbon Dioxide (CO2)

Nitrogen Dioxide (NO2)

Methane (CH4)

Chlorofluorocarbons (CFCs)

Methyl Bromide (CH3Br)

Global Warming Potential

Converts LCI data to carbon dioxide (CO2)

equivalents.

Stratospheric Ozone Depletion

Global Chlorofluorocarbons (CFCs) Hydrochlorofluorocarbons (HCFCs)

Halons

Methyl Bromide (CH3Br)

Ozone Depleting Potential

Converts LCI data to trichlorofluoromethane (CFC-11) equivalents.

Acidification Regional Local

Sulfur Oxides (SOx) Nitrogen Oxides (NOx) Hydrochloric Acid (HCL)

Hydrofluoric Acid (HF)

Ammonia (NH4)

Acidification Potential

Converts LCI data to hydrogen (H+) ion equivalents.

Eutrophication Local Phosphate (PO4)

Nitrogen Oxide (NO) Nitrogen Dioxide (NO2)

Ammonia (NH4)

Eutrophication Potential

Converts LCI data to phosphate (PO4)

equivalents.

Photochemical Smog

Local Non-methane hydrocarbon (NMHC)

Photochemical Oxidant Creation

Potential

Converts LCI data to ethane (C2H6)

equivalents.

Terrestrial Toxicity

Local Toxic chemicals with a reported lethal concentration to rodents

LC50 Converts LC50 data to equivalents; uses multi-

media modeling,

exposure pathways.

Aquatic Toxicity

Local Toxic chemicals with a reported lethal concentration to fish

LC50 Converts LC50 data to

equivalents; uses multi-

media modeling,

exposure pathways.

Human Health Global Regional Local

Total releases to air, water, and soil.

LC50 Converts LC50 data to

equivalents; uses multi-

Media modeling,

exposure pathways.

Resource Depletion

Global Regional Local

Quantity of minerals used Quantity of fossil fuels used

Resource Depletion Potential

Converts LCI data to a ratio of quantity of resource used versus quantity of resource left

in reserve.

Land Use Global

Regional

Local

Quantity disposed of in a landfill or other land modifications

Land Availability Converts mass of solid

waste into volume using

an estimated density.

Water Use Regional Local

Water used or consumed Water Shortage Potential

Converts LCI data to a ratio of quantity of water used versus quantity of resource left in reserve.

11

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.

12

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

13

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

14

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

15

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.

16

17

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

18

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 Technique

Print Resolution [µm]

Print Speed [m/min]

Wet Film 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.

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

Bio-signal

sensor

Flexible cable

Ports for bio-signal electrodes

REF

SCK

SHD

SDA

VCC

(a) (b)

19

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).

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

(a) (b) (c)

20

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.

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

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

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

Samples Spacing/ Width

Induced Voltage on Victim Line (Unit: mV)

Average (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

21

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.

Figure 3. 5 System boundary of paper based flexible cable

Naturalresources

Energy

Conductive Ink Paper

Inkjet Printing Sintering

Paper based Flexible Cable

Waste DisposalRecycling of Ink

and Paper

Emissions

Raw Material

Fabrication Process

22

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

23

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.

24

25

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.

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

on Humanbody

(a) (b)

26

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.

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.

LCA Plan

Instance

Supporting

Interpretation

Calculation Analysis

27

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

Table 4.2 Process Interpretation for Traditional ECG

Flows Amount (kg) Units

Paper Substrates 750 100000

Conductive ink 180 100000

Flows Amount (kg) Units

PVC 1560 100000

Copper Wire

Plastic Parts

9250

1235

100000

100000

28

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

Copper Wire

PVC

Plastic

1560kg

1235kg

9250kg

Traditional

ECG

Cable

29

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.

30

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

31

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.

32

33

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

34

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.

35

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