The flexible future of electronics

Cantatore, E.

Published: 19/05/2017

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Download date: 04. May. 2018

Where innovation starts

/ Department of Electrical Engineering

Inaugural lecture

Prof.dr.ir. Eugenio Cantatore

May 19, 2017

The Flexible Futureof Electronics

Visiting addressAuditorium (gebouw 1)Groene Loper, EindhovenThe Netherlands

Navigation addressDe Zaale, Eindhoven

Postal addressP.O.Box 5135600 MB EindhovenThe Netherlands

Tel. +31 40 247 91 11www.tue.nl/map

Presented on May 19, 2017at Eindhoven University of Technology

Inaugural lecture prof.dr.ir. Eugenio Cantatore

The Flexible Future of Electronics

3

Mr. Rector Magnificus, ladies and gentlemen.Integrated electronics is one of the most pervasive technologies in our world,being at the heart of smart personal devices, computers, communication systems,domestic appliances, vehicles and of the Internet of Everything (IoE): alltechnologies that have become increasingly indispensable to our lifestyle. Integrated circuits are typically built on “chips”: miniature pieces of crystallinesilicon where increasingly smaller field-effect transistors can be packed together.This integration trend, called Moore’s law, has characterized 50 years of amazingprogress in electronics and its ubiquitous applications. In close connection with this development, an increasing number of additionalelectronic devices and processes have been invented to enable sensing, actuationand uncommon form factors. Examples include mature technologies like MEMs orflat-screen displays, together with more recent developments called “emergingtechnologies”. In this inaugural lecture I will describe this fascinating field, with special focus onmy work in flexible electronics. I will introduce the concept of flexible large-areaelectronics, its applications, the scientific challenges that it has to tackle, thedevelopment of this field (with some special attention to my contributions), andthe advancements that will inspire my future research.To conclude, I will also explain why, in my opinion, electronics needs to becomemore and more flexible to address the challenges of the future, not only in a literalsense, but also in a figurative one. On one hand, indeed, electronics mustcooperate more and more with other technologies like integrated photonics, 2Dmaterials and innovative devices to provide unprecedented solutions to demandse.g. in the fields of communication, sensing and biomedical technology. On theother hand, electronics has to overcome some consolidated paradigms, like theseparation between sensing and computation, or the exclusive use of binary bits,to truly step into the future and fully unleash its still unexplored potential.

Introduction

4

Conventional IC electronics is fabricated on slices of monocrystalline silicon, calledwafers, where field effect transistors (FETs) are typically formed using the siliconsubstrate as semiconducting material. A very different way to fabricate field effecttransistors is to deposit the semiconductor layer (and the other layers needed tofabricate the FET structure, e.g. dielectrics and metals) on a non-functionalsubstrate like a glass sheet. In this way a FET stack, called thin-film transistor(TFT), can be formed. The main advantage is that TFTs can be formed on very largeareas, which are nowadays in the order of tens of square meters, at low cost perarea. Monocrystalline Si ICs, by contrast, are fabricated on silicon crystals whichare expensive to make, and wafers are limited today to an area of 0.1 m2. Thanksto its capability to cover large areas with transistor switches, TFT technology isideally suited to fabricating LCD and OLED display panels, which have rapidlybecome the only displays on the market. Each display pixel contains one or moreTFTs to select each color and program its intensity. The disadvantage of TFTs isthat their performance (e.g. switching speed) is far inferior to monocrystallineFETs. Also, TFTs are much larger. However, for applications on a large area, lowerperformance and a large footprint can be tolerated. The material originally used as semiconductor in TFTs is silicon, which can bedeposited to be an amorphous film or annealed in situ to become polycrystalline.About twenty years ago, several research groups demonstrated the possibility todeposit the functional layers of a TFT from solutions, i.e. using ‘inks’. To give anexample, Dago de Leeuw and his co-workers at Philips developed a technologywhere all TFT layers and interconnects were fabricated from carbon-basedmaterials using spin coating [1]. This approach to TFT processing is often describedas ‘organic’, ‘polymer’ or ‘plastic’ electronics. The two novel and very interestingproperties of organic electronics were:1. The use of inks allowed the deposition of the TFT layers at temperatures below

200 °C. This meant that other substrates could be used instead of glass, inparticular flexible plastic films. In this way the concept of large-area flexibleelectronics started to form.

2. Inks can be deposited using techniques normally employed in graphic arts likeinkjet, screen printing or gravure. In this way the concept of ‘printedelectronics’ was born. As printing can be applied to realize very fast deposition

The concept of flexible large-area electronics

5The Flexible Future of Electronics

on rolls of substrates, printed electronics holds the promise of unprecedentedproduction throughput, and thus ultra-low cost, enabling disposableapplications.

This lecture will focus mainly on flexible electronics which does not use printing,but traditional lithography as a method to pattern the TFT films. Examples builtusing printing will be clearly identified.

6

Flexible large-area electronics can be deployed with advantage for all applicationswhere flexibility together with large-area form factor and/or low cost are relevant. The first application which perfectly suits flexible electronics is flexible displays. A display built on a flexible substrate could, for example, be rolled up when is notneeded, occupying minimal space. Several startups and companies [2]-[3] havebeen developing products in this field, but till now no flexible display has beenwidely commercially available. In recent years, not only TFTs but also physical sensors (temperature, pressure,light, etc.) have been developed on flexible substrates. Flexible sensor surfacesare thus another natural application of flexible electronics. Till now on-foilmatrices of pressure sensors [4], ultrasound receivers [5], image sensors [6] and X-ray imagers [7], for example, have been demonstrated. In these devices flexiblesensing elements are integrated on the same foil with addressing electronics builtwith TFTs. This is an extremely active field of research nowadays, with strongefforts to integrate also TFT frontend electronics on the flexible substrate, toimprove signal quality (SNR) and reduce the number of interconnects to theexternal readout circuitry.Due to the potential low-cost per area of flexible (printed) electronics, anotherinteresting application of this technology is in the field of RFIDs, ticketing cardsand anti-counterfeit identification. Many examples of RFIDs built using TFTs onflexible substrates are available (e.g. [8]), and the first NFC-standard compliantRFID made with TFTs on foil was demonstrated earlier this year [9]. This workexploits TFTs made with lithography. The next challenge in this field is, on onehand, to augment RFIDs with sensors [10] and, on the other hand, to realize RFIDsusing printed approaches [11], striving to make them standard-compliant.

Applications and state of the artof flexible large-area electronics

7

A large number of scientific and technological challenges have been addressed toenable the progress of flexible electronics, and many of them are still an activedomain of further research. The most important research directions in this fieldare:

I. MaterialsThe mobility of organic semiconductors, both p and n-type, has witnessedastonishing progress in the last 30 years. From values of 10-3 cm2/Vs which werecommonplace in the early nineties, we have today lots of materials with a mobilityof 10 cm2/Vs or more (Figure 1). Besides, processes have been invented to depositamorphous silicon on flexible substrates, and entire new classes ofsemiconductors that can be processed at low temperature have been developed(metal oxide alloys). The most well-known of these materials, Indium Gallium ZincOxide (IGZO [12]) was reported in 2004 and in 2013 was already being used toproduce large OLED displays available in the market. Other importantdevelopments in the field have been a constant improvement in resilience toenvironmental degradation, which was poor in early organic materials, and thecreation of several materials optimized for sensors.

Scientific challenges

Largest reported carrier mobility oforganic TFTs (measured in ambient air) over time

p-channelorganic TFTs

1980

102

101

100

10-1

10-2

10-3

10-4

10-5

1985 1990 1995 2000 2005 2010 2015

n-channelorganic TFTs

Bes

t rep

orte

dm

obil

ity

(cm

2 /Vs)

YearFigure 1

Evolution in time of best reported mobility for organic p and n-type semiconductors(Courtesy prof.dr. H. Klauk, reproduced with permission).

8 prof.dr.ir. Eugenio Cantatore

II. TFT processing and modelingImportant progress has been achieved also in the field of flexible TFT devicearchitecture and processing. To cite only a few examples: novel device structureswith double gates have been envisaged, which are very useful to circuit design; n and p-type TFTs have been integrated on the same substrate, enablingcomplementary circuits [12]; printed TFTs featuring Source and Drain self-alignedto the Gate have been developed, enabling a remarkable improvement in terms ofspeed [14]; stretchable electronics [15] and TFTs manufactured on films as thin as 1 µm have been demonstrated [16], enabling unprecedented applications likeconformable wearable electronics and electronic tattoos. Another fundamental field of research is the modeling of TFTs, where severalactive groups have proposed compact and physical models that nowadays achievesufficient accuracy to grant accurate simulations of analog circuit topologies [17].

III. Circuits manufactured with TFTsThe design of a circuit based on flexible TFTs is extremely challenging. First of all,TFT performance (like mobility, which is some tens of cm2/Vs as alreadydiscussed), but also intrinsic gain (normally below 40dB) and transition frequency(typically between 1 and 100 MHz) are orders of magnitude inferior to thecorresponding performance of monocrystalline silicon FETs. Then flexible TFTtechnologies are most of the time unipolar only. This makes it impossible toexploit a large spectrum of circuit solutions that have been developed forcomplementary FET in the last 40 years of integrated circuits development whendesigning flexible circuits, and results in substantially worse gain, cumbersomebiasing, decreased DC headroom, higher power supply, reduced power efficiency,etc. Also, flexible TFTs have a strong variability, as the base semiconductor filmsdeposited at low temperature are very non-uniform, and repeatable process stepswhich are commonplace in silicon IC, like ion implantation, are not available inflexible electronics. This variability can result in poor circuit yield and demandsspecial circuit techniques to enhance circuit robustness. Finally, again due to theintrinsic non-uniformity of the base materials and of the processes used tofabricate TFTs, two identical TFTs fabricated on foil close to each other haveperformance that are quite dissimilar, or exhibit poor ‘matching’. This is a problemespecially when building circuits to transform analogue signals into digitalrepresentations, i.e. data converters. Most existing data converters, indeed,exploit the excellent matching properties available in silicon ICs to achieve highresolution and linearity, but this approach is unsuited to flexible TFT technologies.

9

The global research effort in the design of circuits for flexible electronics hasstrongly advanced the state of the art in terms of device count, performance andfunctional complexity. In this section my contributions to this general progress willbe outlined in brief. They focus on two main objectives:

I. Design of digital circuits manufactured with organic TFTs on flexible substratesA main enabler to applications of flexible electronics is the possibility tomanufacture large digital circuits (e.g. row addressing registers for displays, RFIDcode generators) with good yield. This turned out to be a daunting task. OrganicTFTs, indeed, are typically only p-type. Besides, for organic materials there is nosimple and reliable process to tune the threshold voltage in TFTs: for this reason, it is difficult to realize in the same process depletion and enhancement thin-filmtransistors. Given the absence of complementary and depletion/enhancement TFTpairs, the design of logic gates that are highly immune to the variability of TFTparameters is particularly challenging, and for years only very small circuits couldbe manufactured (< 100 TFTs) with some yield. One should also note that ageing,i.e. TFT parameter shift due to environmental aggressors or electric biasing, hassimilar effects to TFT variability from a circuit point of view. Robustness to TFTvariability is thus also beneficial to increase resilience to ageing1. In this fieldseveral breakthroughs have been achieved:

a. Design of p-only organic inverters with level shiftersThe static noise margin has been determined to be a good figure of merit to studythe effect of TFT parameter variability on the correct functionality of logic gates,and to predict yield from a statistical perspective. The noise margin of diode-loadorganic p-only inverters has been increased using a novel level-shifter stage, atthe same time enabling relatively high speed and good yield. Following thisapproach, in 2004 it was demonstrated a 32-stage shift register that can be used

Personal contributions to thedevelopment of flexible electronics

1 Organic TFT stability has been improving tremendously with time thanks to advances in materials andbarrier layers. Nowadays organic circuits can be stored and work for years in air.

10 prof.dr.ir. Eugenio Cantatore

as row driver for a flexible display. The clock speed was 5 kHz and the circuitcontained 1888 TFTs, the largest organic circuit at that time [18].

b. Design of p-only organic TFT inverters for maximum noise margin In a specific organic TFT process developed at Philips, Zero-Vgs load p-onlyinverters have been dimensioned to ensure the maximum average noise margin,while tuning the process conditions needed to guarantee sufficient zero-Vgscurrent from the TFTs. In this way, a 64-bit code generator for an RFID, the mostcomplex organic digital circuit at that time with 1938 TFTs, was demonstrated [8] in2006. The circuit (Figure 2) was also optimized to avoid races and improvetestability, choosing an architecture based on barrel shift registers as opposed toa synchronous counter. This paper also demonstrated for the first time an organicRFID capable of transmitting multi-bit codes to a base station (Figure 3) using thestandard 125 kHz and 13.56 MHz RFID carriers.

c. Design of p-only organic inverters with dual-gate TFTsFor the first time the use of double-gate TFTs for all TFTs in an inverter has beendemonstrated to be extremely beneficial in increasing the noise margin and thusthe yield of organic digital circuits [19].

Figure 2

Flexible organic 64b RFID glued on a piece of PCB and bonded to a capacitive RFIDantenna.

11The Flexible Future of Electronics

d. Design of p-only dual-gate organic inverters with level shifters and positivefeedbackThe use of dual-gate TFTs has allowed the design of a new logic style, whichexploits positive feedback, together with a level shifter. The trip voltage of theinverters and NANDs built in this logic style can be adjusted using a tuningvoltage, allowing the trip point to be tuned back to the mid of the voltage railswhen TFT parameter variations cause excessive deviations from this desired value.The positive feedback increases the gain of the digital gates further, improving thenoise margin up to 41% of the supply voltage. The characteristics of this logicstyle, called Positive-Feedback Level Shifter (PLS), enable unprecedentedrobustness against TFT variability, making it possible to build functional 240-stageshift registers. These circuits, the largest organic circuits to date, contain 13,440TFTs each (Figure 4 - [20]).

Figure 3

A 6b organic RFID is readout by a base station, showing its code on the oscilloscope.

12 prof.dr.ir. Eugenio Cantatore

e. Statistical design of complementary organic inverters for maximum noisemarginIn recent years n-type organic semiconductors have been tremendously improvedfrom the point of view of stability in air, and thus complementary organicelectronics has become possible in practical applications. The statistics of the TFTparameters in a complementary organic process has been characterized, and dueto the fact that the threshold can be both positive and negative for n-type devices,a fully static CMOS logic style has been selected to design a 32-stage shiftregister. The circuit is fully functional, has a maximum clock speed of 2.5 kHz and,with 1216 TFTs is the largest complementary organic circuit ever demonstrated [21].This shift register has been used to drive the rows of an OLED display. The yield ofcomplementary organic technology is nowadays limited by hard faults, and for thisreason is still inferior to the p-type organic processes (which have a lower hard-faults count).

II. Design of data converters manufactured with TFTs on flexible substratesAs discussed above, promising applications of organic and flexible electronicsrequire interfacing with physical sensors. For this reason, a broad researchprogram on analogue and mixed-signal electronics made with TFTs manufacturedon foil has been started at Eindhoven University of Technology, with a strong focuson analog to digital converters (ADCs). As discussed briefly above, the maintechnical challenges include: extremely large mismatch (the offset of a differential

a)

240-stage Shift Register 10-DFF Module

DFF

b)

Figure 4

Micrograph of a 240-stage organic shift register designed using PLS logic (adapted from[20]).

13The Flexible Future of Electronics

pair can be as high as a few volts, especially in printed technologies), parametervariability, limited access to complementary devices and limited intrinsic gain in aTFT. To overcome these difficulties, experiments have been performed on the useof an integrating architecture based on a VCO with good intrinsic linearity and acounter [22] to build an ADC with organic TFTs. This organic converter attainsstate-of-the-art characteristics, reaching an SNR of 48 dB (in a 0.16 Hz bandwidth)and a maximum INL of 1 LSB at 6 bit resolution. At TU/e we also investigated the design of ADCs built with printed complementaryorganic technologies. In this case, due to the severe mismatch and reduced digitalcomplexity achievable with sufficient yield, a simple 4 bit counting architecturehas been demonstrated. The chosen DAC architecture is based on a resistive R2Rladder, which offers better DNL than TFT-based counterparts. The proposedcomparator employs two stages, both featuring offset cancellation (which isenabled by the use of complementary pass-gates). This research resulted in thefirst functional printed ADC ever published, which reaches an SNR of 26.6 dB andSNDR of 19.6 dB [23] (Figure 5). The performance of comparator and DAC havebeen further improved over time, with recent measurements showing that both thecomparator offset and the DAC DNL can be below 1 LSB at a 7 bit resolution level.

Figure 5

Photo of the printed 4b ADC manufactured with printed complementary organic technology(Copyright Bart van Overbeeke Fotografie, reproduced with permission).

14 prof.dr.ir. Eugenio Cantatore

In recent years, IGZO (Indium-Gallium-Zinc Oxide) has been emerging as anexcellent semiconductor for large-area electronics on flexible foils. It features goodmobility (> 10 cm2/Vs) and better uniformity than organic competitors. Based onthese characteristics, our group has proposed for the first time the use of IGZO ina DAC for display applications. Given the reasonable uniformity, a current steeringarchitecture has been proposed [24], achieving good static and dynamic linearity.Still exploiting IGZO, an asynchronous delta-sigma modulator (ADSM), which isable to convert an analog signal to a binary pulse-width modulated (PWM)representation with good fidelity, has been built. The PWM representation can beused to send the signal over a cable or via radio with high immunity to noise andinterferers. This ADSM achieves good noise and linearity performance comparedto previous state-of-the-art in data converters on foil: the maximum signal to noiseand distortion ratio is 50 dB for a signal bandwidth of 10 Hz, while currentconsumption is 100 µA (Figure 6). The ADSM has also been integrated with aflexible resistive temperature sensor, to convert its temperature-dependent signalto PWM [25].

Figure 6

Measurement setup used for the characterization of the ASDM manufactured with IGZOTFTs on foil. The foil is glued on a temporary glass substrate (Copyright Ivar Pel,reproduced with permission).

15

Flexible electronics still offers fields of applications that are largely unexplored.These applications can serve well as a stimulus for further, cutting-edge researchin circuit design. The future research plan of our group in flexible electronics willfocus on two main directions.

I. Biomedical and biochemical sensingTFT processed at low temperature enables not only flexible, but even stretchableand conformable substrates, making these TFTs the ideal choice to buildelectronics to pick up signals on and around the body and thus an ideal solutionto map biopotentials. Biopotentials are minute dynamic voltages generated byheartbeat (electrocardiogram – ECG), cerebral activity (electroencephalogram-EEG), muscle (electromiogram – EMG) or uterus contraction (electrohysterogram –EHG), among others, which can be measured on the skin. These potentials arespatially distributed and need to be detected on large surfaces to providesignificant clinical information. For this reason, state-of-the-art solutions still relyon complicated ad-hoc assemblies of electrodes, wiring and electronics boxes,which are cumbersome to set up and uncomfortable for the patient. By contrast, flexible electronics can provide a convenient way to manufacture amatrix of electrodes and pick up the biopotentials with integrated frontendelectronics (Figure 7). The TFTs can also multiplex the signal of many different

Future research in flexiblelarge-area electronics

Silicon readout chipmounted on the edge

Thin plastic substrateto be mostly cut away

by laser

StretchableConnection bus

Electrode

IGZO Front-end

Radio link

Battery

Figure 7

Conceptual sketch of a biopotential measurement foil exploiting TFTs together with anintegrated silicon IC.

16 prof.dr.ir. Eugenio Cantatore

electrodes to a conventional silicon IC, which provides conversion to a digitalrepresentation and wireless communication of the data to an elaboration hub, forexample. Multiplexing drastically reduces the number of interconnects betweenthe biopotential measurement foil and Si chip, cutting down costs. A comfortableand low-cost solution to biopotential measurements can thus be provided. Anactive research project is ongoing in this field, in close cooperation with HolstCentre (prof.dr. Gerwin Gelinck).A recent development in the field of sensors based on low-temperature processingis the discovery of ultra-sensitive biochemical sensors ([26]-[27]). In perspective,these sensors can be arranged in large matrices to enable complex biochemicalassays, and TFT electronics can be used again for addressing and multiplexing ofthe sensor signals to a silicon IC, providing low-cost and extremely high-performance solutions. More work in this field is envisaged in the near future.

II. Low-cost printed electronics Printed electronics remains a huge challenge. At the state-of-the-art TFT yield isstill low, with typically between 1% and 1‰ of TFTs showing hard failures (i.e.shorts, opens, excessive leakage, etc.). On top of this, TFT variability is extremelypronounced, and mismatch particularly strong. All these characteristics makecircuit design in printed technologies particularly challenging. High risk, thus, butalso high reward, as printing enables a whole range of applications that canbecome so low cost to be disposable. In this field, within the H2020 ATLASSproject, we want to work on disposable pressure sensors based on piezoelectricsensors (Figure 8), and on RFID augmented with simple temperature sensors.

System Integration

Pixel

Organic frontend

Pressure sensor

Organic line drivers

AD

C

Si electronics

Foil lamination

Sensor frontplane

OTFT backplane

Figure 8

Conceptual sketch of a disposable printed pressure sensor foil (courtesy Marco Fattori).

17The Flexible Future of Electronics

Especially the latter effort is extremely demanding as, on one hand, one needs toprovide frontend electronics and conversion to digital representation for thesensor data, and, on the other hand, one has to build RF waves harvesters andload modulation circuitry. This research, which ultimately targets applications likemonitoring of food conservation quality through measurements of theenvironmental conditions (e.g. temperature, humidity, C02) via sensors printed onthe food wrapping (Figure 9) is a typical example of a grand challenge in the fieldof printed electronics. For its high societal relevance (reduction of food waste) andcomplexity, this is probably one of the most fascinating research objectives in ourfield.

Good!

Figure 9

Conceptual sketch of a disposable food monitoring sensor integrated in the package of aready-to-eat salad. The smart reader (e.g. a smart phone) evaluates the food conservationquality based on the sensor measurements.

18

Flexible electronics is not the only technology that has been invented in parallel tothe Moore’s law IC developments. There is a wide range of additionaltechnologies, many of which are emerging just now, which can be a tremendousstimulus in advancing electronics further. The mission of the chair in Circuit Designfor Emerging Technologies is “is to design circuits and systems which exploit noveltechnologies, in order to expand the application domain of electronics beyondwhat is conventionally possible with silicon Integrated Circuits (ICs) alone.”In an effort to put this mission into practice, there are two examples of emergingtechnologies on which I will explore in the near future. 1. Integration of Photonic ICs (PICs) and electronic integrated circuits (ICs).

Photonic integration is a strong and credible emerging trend in moderntechnology. Eindhoven University of Technology has a leading positionworldwide in this field, with the Institute for Photonic Integration and theCobra research institute. Exploiting the synergy with this excellent localcompetence, we are defining research projects on the 3D integration ofintegrated photonics and electronics, both in the field of communication and inthe field of advanced sensors.

2. Integration of 2D materials above ICs. 2D materials, probably the most widelyknown of which is graphene, have unique properties both from the mechanicand the electronic perspective. Although the direct use of 2D materials assemiconductors in a mature technology for ICs seems unlikely nowadays, 2Dmaterials might have very interesting applications in sensing devices,especially for biochemical applications. The integration of 2D materials in thebackend of line of conventional IC technologies has thus the potential toenable sensor systems where the silicon IC is intimately integrated with noveldevices, enabling unprecedented functionalities. This is another extremelyinteresting opportunity in the field of emerging technologies, and it will beexploited with the support of experts in the field of 2D materials and devices.

Future research in otheremerging technologies

19

Emerging technologies are a rich and dynamic field of research which can inspirethe progress of electronics. The research in flexible electronics is an example ofhow novel devices and manufacturing processes can motivate challenging work incircuit and system design to enable unprecedented applications. My research inthis field will continue with special focus on biomedical and biochemicalfunctionalities, as well as on printed sensor surfaces and sensor-augmented RFIDson foil.I believe that electronics is reaching a mature point of its history. We thus need tobecome flexible ourselves, to reinvent electronics and continue its progress. On one hand, inspiration can come from merging electronics with other noveltechnologies and devices. Integration between ICs and photonics, and integrationof 2D materials in the backend of silicon FET processes are two possible andpromising examples which trigger my curiosity. On the other hand, flexibilitymeans to have the courage to abandon paradigms that have remainedunchallenged for too long. I would like to mention two examples. In modernelectronic systems sensing, analogue electronics and elaboration of the sensordata are typically separate domains, with extremely limited interaction. This limitsthe capability of our systems to adapt to varying environmental/usage conditionsand is one of the major limitations of present IoE. Interesting efforts to break thisway of thinking involve machine learning and novel architectures that intimatelylink computation and sensing. Another example is in the domain of computation.For most of us the word ‘bit’ is a synonym of a binary quantity: either a ‘0’ or a ‘1’.The emerging interest in quantum computing witnesses the incredible progressthat would open up if we could manipulate in a practical way quantum bits thatcan be 0 and 1 at the same time, a so-called superposition state. This is justanother example of how important is to break up the usual way of thinking andexploit the flexibility of our intelligence to ensure a bright future to electronics andto our society.

Conclusions

20

I would like to thank the former and the present deans of Electrical Engineering,Prof.dr.ir. Ton Backx and Prof.dr.ir. Bart Smolders for their much appreciatedsupport to my promotion. I gratefully thank my former and present group leaders,Prof.dr.ir. Arthur van Roermund and Prof.dr.ir. Peter Baltus for their leadership,help and friendship. All the work presented in this lecture as well as the futureresearch could not be possible without the collaboration and support of a largenumber of colleagues. To list only few, I would like to especially thank mycolleagues in the MSM group of Electrical Engineering at TU/e, all the formerPhilips Polymer Electronics project, the former PolymerVision staff, the formerSapiens staff, the colleagues from Holst Centre, IMEC, CEA-Liten, CERN,Fraunhofer EMFT, VTT, Johanneum research, Philips, NXP, STM, PragmatIC,Thinfilm, Plastic Logic, Merck, Flexenable, GRT, AMO, Arkema, IN-CORE, Shadow,Concept Tech, ISSCC, University and Politecnico of Bari, University of Brescia,University of Catania and many more. A special acknowledgement goes to mypresent and past Master students, doctoral students, PDEng candidates andpostdocs for their tremendous help, patience and commitment to their research. A special thought also to all my undergraduate students, for the incredible energythey are able to give me each time I can work with them.A special thank goes finally to my beloved family and my dear friends: withoutyour love, patience and continuous support nothing of what I have achieved couldhave been possible.Thanks to you all for your kind patience and your interest in my research.

Acknowledgements

21

1. G.H. Gelinck, T.C.T. Geuns, and D.M. de Leeuw “High-performance all-polymer integrated circuits” Appl. Phys. Lett. 77, 1487 (2000).

2. Available at http://www.flexenable.com/3. Available at http://www.plasticlogic.com/4. Y. Noguchi, T. Sekitani, and T. Someya “Organic-transistor-based flexible

pressure sensors using ink-jet-printed electrodes and gate dielectric layers”Appl. Phys. Lett. 89, 253507 (2006).

5. Y. Kato, T. Sekitani, Y. Noguchi, T. Yokota, M. Takamiya, T. Sakurai, T. Someya,“Large-Area Flexible Ultrasonic Imaging System with an Organic TransistorActive Matrix” IEEE Trans. El. Dev. 55, 57, 5 pp. 995-1002 (2010).

6. I. Nausieda, K. Ryu, I. Kymissis, A.I. Akinwande, V. Bulovic, C.G. Sodini, “AnOrganic Active-Matrix Imager” IEEE Trans. El. Dev. 55,2 pp. 527-532 (2008).

7. G.H. Gelinck, A. Kumar, D. Moet, J.P.J. van der Steen, A.J.J.M. van Breemen, S. Shanmugam, A. Langen, J. Gilot, P. Groen, R. Andriessen, M. Simon, W. Ruetten, A.U. Douglas, R. Raaijmakers, P.E. Malinowski, K. Myny, “X-RayDetector-on-Plastic With High Sensitivity Using Low Cost, Solution-ProcessedOrganic Photodiodes” IEEE Trans. El. Dev. 63,1 pp. 197 – 204 (2016).

8. E. Cantatore, T.C.T. Geuns, G.H Gelinck, E. van Veenendaal, A.F.A.Gruijthuijsen, L. Schrijnemakers, S. Drews, D.M. de Leeuw, “A 13.56-MHzRFID system based on organic transponders” IEEE Journal of solid-statecircuits 42,1, pp. 84-92 (2007).

9. K. Myny, Yi-Cheng Lai, N. Papadopoulos, F. De Roose, M. Ameys, M.Willegems, S. Smout, S. Steudel, W. Dehaene, J. Genoe, “A flexible ISO14443-A compliant 7.5mW 128b metal-oxide NFC barcode tag with direct clockdivision circuit from 13.56MHz carrier” 2017 IEEE International Solid-StateCircuits Conference (ISSCC) p. 258-259 (2017)

10. Available at http://thinfilm.no/11. V. Fiore, P. Battiato, S. Abdinia, S. Jacobs, I. Chartier, R. Coppard, G. Klink,

E. Cantatore, E. Ragonese, G. Palmisano, “An Integrated 13.56-MHz RFID Tagin a Printed Organic Complementary TFT Technology on Flexible Substrate”IEEE Transactions on Circuits and Systems I: Regular Papers, 62, 6 pp. 1668-1677 (2015).

References

22 prof.dr.ir. Eugenio Cantatore

12. K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, “Room-temperature fabrication of transparent flexible thin-film transistors usingamorphous oxide semiconductors” Nature 432, pp. 488-492 (2004).

13. S. Jacob, M. Benwadih, J. Bablet, I. Chartier, R. Gwoziecki, S. Abdinia, E. Cantatore, L. Maddiona, F. Tramontana, G. Maiellaro, L. Mariucci, G. Palmisano, R. Coppard, “High performance printed N and P-type OTFTs forcomplementary circuits on plastic substrate” Proceedings of the EuropeanSolid-State Device Research Conference (ESSDERC), pp. 173-176 (2012).

14. H. Gold, A. Haase, A. Fian, C. Prietl, B. Striedinger, F. Zanella, N. Marjanovic,R. Ferrini, J. Ring, K.-D. Lee, R. Jiawook, A. Drost, M. König, R. Müller, K. Myny,J. Genoe, U. Kleb, H. Hirshy, R. Prétôt, J. Kraxner, R. Schmied, B. Stadlober,“Self-aligned flexible organic thin-film transistors with gates patterned bynano-imprint lithography” Organic Electronics 22 pp. 140-146 (2015).

15. J.A. Fan, W.-Hong Yeo, Y. Su, Y. Hattori, W. Lee, Sung-Young Jung, Y. Zhang, Z. Liu, H. Cheng, L. Falgout, M. Bajema, T. Coleman, D. Gregoire, R.J. Larsen,Y. Huang & J.A. Rogers., “Fractal design concepts for stretchable electronics”Nature Communications 5, 3266 (2014)

16. H. Fuketa, K. Yoshioka, Y. Shinozuka, K. Ishida, T. Yokota, N. Matsuhisa, Y. Inoue, M. Sekino, T. Sekitani, M. Takamiya, T. Someya, T. Sakurai, “1 µm-Thickness Ultra-Flexible and High Electrode-Density Surface ElectromyogramMeasurement Sheet With 2 V Organic Transistors for Prosthetic HandControl” IEEE Trans. Biomedical Circuits and Systems, 8,6 pp. 824-833(2014).

17. M. Ghittorelli, F. Torricelli, C. Garripoli, J.L. van der Steen, G.H. Gelinck, E. Cantatore, L. Colalongo, & Z.M. Kovács-Vajna, “Unified physical DC modelof staggered amorphous InGaZnO transistors” IEEE Transactions on ElectronDevices 64, 3, pp. 1076-1082 (2017).

18. G.H. Gelinck, H.E.A. Huitema, E. van Veenendaal, E. Cantatore, L.Schrijnemakers, J.B.P.H. van der Putten, T.C.T. Geuns, M. Beenhakkers, J.B.Giesbers, B. Huisman, E.J. Meijer, E. Mena Benito, F.J. Touwslager, A.W.Marsman, B.J.E. van Rens and D.M. de Leeuw, “Flexible active-matrix displaysand shift registers based on solution-processed organic transistors” NatureMaterials 3, 106-110 (2004).

19. M. Spijkman, E.C.P. Smits, P.W.M. Blom, D.M. De Leeuw, Y. Bon Saint Come,S. Setayesh, E. Cantatore, “Increasing the noise margin in organic circuitsusing dual gate field-effect transistors” Applied Physics Letters 92, 14, p. 123(2008).

23The Flexible Future of Electronics

20. D. Raiteri, P. van Lieshout, A.H.M. van Roermund, & E. Cantatore, “Positive-feedback level shifter logic for large-area electronics” IEEE Journal of Solid-State Circuits. 49, 2, p. 524-535 (2014).

21. S. Abdinia, T.H. Ke, M. Ameys, J. Li, S. Steudel, J.L. Vandersteen, B. Cobb, F. Torricelli, A.H.M. van Roermund, & E. Cantatore, “Organic CMOS linedrivers on foil” IEEE/OSA Journal of Display Technology, 11, 6, pp. 564-569 6p., 7083700 (2015).

22. D. Raiteri, P. van Lieshout, A.H.M. van Roermund, & E. Cantatore, “An organicVCO-Based ADC for quasi-static signals achieving 1LSB INL at 6b resolution”Proceedings of the 60th IEEE International Solid-State Circuits Conference(ISSCC 2013), p. 108-109 (2013).

23. S. Abdinia, M. Benwadih, R. Coppard, S. Jacob, G. Maiellaro, G. Palmisano, M. Rizzo, A. Scuderi, F. Tramontana, A.H.M. van Roermund, & E. Cantatore, “A 4b ADC manufactured in a fully printed organic complementarytechnology including resistors” Proceedings of the 60th IEEE InternationalSolid-State Circuits Conference (ISSCC 2013), p. 106-107 (2013).

24. D. Raiteri, F. Torricelli, K. Myny, M. Nag, B. Van der Putten, E.C.P. Smits, S. Steudel, K. Tempelaars, A.K. Tripathi, G.H. Gelinck, A.H.M. van Roermund,& E. Cantatore, “A 6b 10MS/s current steering DAC manufactured withamorphous gallium-indium-zinc-oxide TFTs achieving SFDR > 30 dB up to 300 kHz” Proceedings of the IEEE International Solid-State CircuitsConference 2012 (ISSCC 2012), p. 314-316 (2012).

25. C. Garripoli, J.-L.P.J. van der Steen, E. Smits, G.H. Gelinck, A.H.M. VanRoermund, E. Cantatore, “An a-IGZO asynchronous delta-sigma modulator onfoil achieving up to 43dB SNR and 40dB SNDR in 300Hz bandwidth” 2017IEEE International Solid-State Circuits Conference (ISSCC) p. 260-261 (2017).

26. E. Macchia, D. Alberga, K. Manoli, G. Mangiatordi, M. Magliulo, G. Palazzo, F. Giordano, G. Lattanzi, L. Torsi “Organic bioelectronics probingconformational changes in surface confined proteins” Scientific reports 6:28085 (2016).

27. S. Lai, M. Barbaro, A. Bonfiglio, “Tailoring the sensing performances of anOFET-based biosensor” Sensors and Actuators B: Chemical, 233, 5 p. 314-19(2016).

24

Eugenio Cantatore received his Master’s and PhD Degree inElectrical Engineering from Politecnico di Bari, in 1993 and1997 respectively. From 1997 to 1999 he was fellow at theEuropean Laboratory for Particle Physics (CERN), Geneva. In 1999 he moved to Philips Research, Eindhoven, as seniorscientist and in 2007 joined Eindhoven University ofTechnology, where he has been full professor since 2016.His research interests include the design andcharacterization of electronic circuits exploiting emergingtechnologies and the design of ultra-low power micro-systems. He has authored or co-authored more than 150papers in journals and conference proceedings, and 13patents or patent applications. He is active in the TechnicalProgram Committees of IWASI, ESSDERC, ESSCIRC andISSCC. From 2013 till 2016 he was chair of the TechnologyDirections subcommittee, and he is presently Program vice-chair of ISSCC. In 2006 he received the Beatrice WinnerAward for Editorial Excellence from ISSCC and wasnominated in the Scientific American top 50 list. Hereceived the Philips Research Invention Award in 2007, the Best Paper Award from ESSDERC in 2012 and theDistinguished Technical Paper Award from ISSCC in 2015.Eugenio Cantatore is a fellow of the IEEE.

Curriculum VitaeOn 1 May, 2016 Prof.dr.ir. Eugenio Cantatore was appointed professor of Circuit

Design for Emerging Technologies in the Department of Electrical Engineering atEindhoven University of Technology (TU/e).

Colophon

ProductionCommunicatie Expertise Centrum TU/e

Cover photographyRob Stork, Eindhoven

DesignGrefo Prepress,Eindhoven

PrintDrukkerij Snep, Eindhoven

ISBN 978-90-386-4296-3NUR 959

Digital version:www.tue.nl/lectures/

Where innovation starts

/ Department of Electrical Engineering

Inaugural lecture

Prof.dr.ir. Eugenio Cantatore

May 19, 2017

The Flexible Futureof Electronics

Visiting addressAuditorium (gebouw 1)Groene Loper, EindhovenThe Netherlands

Navigation addressDe Zaale, Eindhoven

Postal addressP.O.Box 5135600 MB EindhovenThe Netherlands

Tel. +31 40 247 91 11www.tue.nl/map