A High Sensitivity Three-Dimensional-Shape Sensing Patch Prepared by Lithography and Inkjet Printing

A process combining conventional photolithography and a novel inkjet printing method for the manufacture of high sensitivity three-dimensional-shape (3DS) sensing patches was proposed and demonstrated. The supporting curvature ranges from 1.41 to 6.24 × 10−2 mm−1 and the sensing patch has a thickness of less than 130 μm and 20 × 20 mm2 dimensions. A complete finite element method (FEM) model with simulation results was calculated and performed based on the buckling of columns and the deflection equation. The results show high compatibility of the drop-on-demand (DOD) inkjet printing with photolithography and the interferometer design also supports bi-directional detection of deformation. The 3DS sensing patch can be operated remotely without any power consumption. It provides a novel and alternative option compared with other optical curvature sensors

소프트 리소그래피를 통한 탄소나노튜브 복합체의 다목적 및 저비용의 고해상도 패터닝 방법

학위논문(박사) -- 서울대학교대학원 : 융합과학기술대학원 융합과학부(나노융합전공), 2023. 2. 송윤규.Carbon nanotube (CNT) is a promising electronic material with superior properties such as high electrical conductance, mechanical strength, and environmental friendliness. Accordingly, studies for commercialization are being actively conducted for applying CNTs to various practical fields. Despite these excellent properties and the effort to use them, however, the commercialization of CNTs has been slow, and one of the reasons is the difficulty in patterning them. Numerous methods for patterning CNTs have been developed to overcome the problem, and many studies have been reported to implement devices using them. This dissertation deals with developing and applying the CNT patterning method. The developed method not only solves the problems of the conventional methods but also has differentiated advantages. CNT is prepared in composite by mixing with paraffin, an organic material, and patterned via soft-lithography techniques. Therefore, the first chapter will explain the background of the two materials, CNT and paraffin, and their significance in this study. It also describes soft-lithography and related techniques, the patterning methods used. Moreover, It introduces challenges to be solved simultaneously with the conventional CNT patterning method and presents future directions. The CNT patterning method and results are presented in detail in the second chapter. The employment of paraffin and soft-lithography offers several advantages in terms of cost and accessibility, as well as process and pattern properties. Significantly, the two most critical advantages are that high-resolution (<10 μm) patterning is possible and printing on various substrates. In addition, optical, electrical, thermal, and mechanical analyses introduce multiple characteristics of CNT composite patterns. Meanwhile, the remaining CNT residues and paraffin in the pattern can have a negative effect, such as a short circuit. In addition, the transfer process could be difficult on substrates with very low surface energy. Thus, the following chapter discusses these issues and describes additional processes to improve the quality and properties of the CNT composite pattern. In the end, a high-performance, flexible, and miniaturized touch sensor and energy harvesting device were fabricated using the printed CNT composite pattern. By utilizing the advantages of high-resolution patterning and no restriction on the substrate, it was possible to manufacture devices with improved performance. It suggests that the CNT composite pattern can be applied to various fields. The fabrication and results of the device will be introduced in the last chapter.탄소나노튜브는 높은 전기 전도도 및 기계적 강도 등의 우수한 특성들을 가진 유망한 전자 재료이다. 따라서, 탄소나노튜브를 여러 분야에 적용하기 위한 상용화 연구가 활발히 진행중이다. 하지만 이러한 우수한 물성과 노력에도 불구하고 탄소나노튜브의 상용화는 더딘데, 그 이유 중 하나로 패턴화의 어려움을 들 수 있다. 이를 극복하기 위해, 탄소나노튜브를 패터닝하는 다양한 방법들이 개발되어 왔으며, 이를 이용하여 소자를 구현하는 많은 연구들이 보고되고 있다. 본 학위 논문은 탄소나노튜브 패터닝 방법의 개발과 응용에 대해 다루고 있다. 개발된 패터닝 방법은 기존 방식의 문제점들을 해결할 뿐만 아니라 차별화된 장점을 가지고 있다. 이를 위해서 탄소나노튜브를 유기물인 파라핀과 혼합하여 탄소나노튜브 복합체를 제조하였으며, 소프트 리소그래피 기술을 통해 패터닝하였다. 첫 번째 장에서는 탄소나노튜브와 파라핀 두 물질의 배경과 본 연구에서의 의의를 설명하며, 사용된 패터닝 방법인 소프트 리소그래피 및 관련 기술에 대해서도 설명한다. 더 나아가, 기존의 탄소나노튜브 패터닝 방법을 소개함과 동시에 해결해야 할 문제점을 설명하고 향후 탄소나노튜브 패터닝의 방향을 제시한다. 두 번째 장에서는 탄소나노튜브의 패터닝 방법과 결과를 자세히 보여준다. 파라핀과 소프트 리소그래피의 사용은 비용 및 접근성을 우수하게 할 뿐만 아니라 공정과 패턴의 특성 면에서 여러 이점들을 제공한다. 특히, 여러가지 장점들 중 가장 중요한 두 가지는 고해상도(<10 μm)의 패터닝이 가능하다는 것과 다양한 종류의 기판에 인쇄될 수 있다는 것이다. 이 외에도 광학적, 전기적, 열적, 기계적 분석 등을 통해 탄소나노튜브 복합체 패턴의 다양한 특성들을 소개한다. 한편, 패턴에 남아있는 탄소나노튜브 잔류물 및 파라핀은 회로 단락과 같은 부정적인 결과를 초래할 수 있다. 뿐만 아니라, 표면 에너지가 매우 낮은 기판에서는 전사 공정이 어려울 수도 있다. 따라서, 세 번째 장에서는 패턴과 공정과정에서 발생하는 이러한 문제들에 대해 논의하고, 탄소나노튜브 패턴의 품질 및 특성을 개선하기 위한 추가 프로세스에 대해 기술한다. 마지막으로 인쇄된 탄소나노튜브 복합체 패턴을 이용하여 고성능의 유연하고 소형화된 터치 센서와 에너지 하베스팅 소자를 제작하였다. 앞서 기술한 고해상도의 패터닝이 가능하다는 것과 기판에 제약이 없다는 두 장점을 활용하여 우수한 성능의 소자들을 제작할 수 있었다. 이는 탄소나노튜브 복합체 패턴이 다양한 분야에 적용될 수 있으며, 탄소나노튜브의 상업화에 기여할 수 있는 가능성을 시사한다. 소자의 제작 및 결과는 마지막 장에서 소개될 것이다.Chapter 1. Introduction 1 1.1. Characteristics of carbon nanotube (CNT) 1 1.2. Properties of paraffin wax 4 1.3. Soft-lithography and transfer printing 7 1.4. Patterning method of CNT 18 Chapter 2. Patterning of CNT/paraffin composite via soft-lithography 22 2.1. Introduction 22 2.2. Experiments 25 2.2.1. Sample preparation 25 2.2.2. Patterning process of the CNT/paraffin composite 29 2.2.3. Characterization of the composite 30 2.3. Results 35 2.3.1. Optical measurements 35 2.3.2. Electrical measurement 40 2.3.3. Thermogravimetric analysis (TGA) 43 2.3.4. Mechanical & healing properties measurement 45 2.4. Summary 54 Chapter 3. Improving the CNT/paraffin pattern 56 3.1. Paraffin cleaning process for residue removing 56 3.2. Minimize bending radius peeling method 61 3.3. Paraffin removal process 68 3.4. Summary 75 Chapter 4. Applications 76 4.1. Capacitive touch sensor 76 4.1.1. Introduction 76 4.1.2. Device fabrication 79 4.1.3. Results 82 4.2. Water-drop energy harvesting 87 4.2.1. Introduction 87 4.2.2. Device fabrication 94 4.2.3. Results 96 4.3. E-textile for wearable electronics 102 4.3.1. Introduction 102 4.3.2. Device fabrication 108 4.3.3. Results 110 4.4. Summary 130 Chapter 5. Conclusion 132 Bibliography 135 국문 초록 146박

Recent Advances on 2D Materials towards 3D Printing

In recent years, 2D materials have been implemented in several applications due to their unique and unprecedented properties. Several examples can be named, from the very first, graphene, to transition-metal dichalcogenides (TMDs, e.g., MoS2), two-dimensional inorganic compounds (MXenes), hexagonal boron nitride (h-BN), or black phosphorus (BP). On the other hand, the accessible and low-cost 3D printers and design software converted the 3D printing methods into affordable fabrication tools worldwide. The implementation of this technique for the preparation of new composites based on 2D materials provides an excellent platform for next-generation technologies. This review focuses on the recent advances of 3D printing of the 2D materials family and its applications; the newly created printed materials demonstrated significant advances in sensors, biomedical, and electrical applications.Financial support from Operational Program Research, Development and Education-Project “MSCAfellow4@MUNI” (CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged

Design and development of a microfluidic platform for use with colorimetric gold nanoprobe assays

Due to the importance and wide applications of the DNA analysis, there is a need to make genetic analysis more available and more affordable. As such, the aim of this PhD thesis is to optimize a colorimetric DNA biosensor based on gold nanoprobes developed in CEMOP by reducing its price and the needed volume of solution without compromising the device sensitivity and reliability, towards the point of care use. Firstly, the price of the biosensor was decreased by replacing the silicon photodetector by a low cost, solution processed TiO2 photodetector. To further reduce the photodetector price, a novel fabrication method was developed: a cost-effective inkjet printing technology that enabled to increase TiO2 surface area. Secondly, the DNA biosensor was optimized by means of microfluidics that offer advantages of miniaturization, much lower sample/reagents consumption, enhanced system performance and functionality by integrating different components. In the developed microfluidic platform, the optical path length was extended by detecting along the channel and the light was transmitted by optical fibres enabling to guide the light very close to the analysed solution. Microfluidic chip of high aspect ratio (~13), smooth and nearly vertical sidewalls was fabricated in PDMS using a SU-8 mould for patterning. The platform coupled to the gold nanoprobe assay enabled detection of Mycobacterium tuberculosis using 3 8l on DNA solution, i.e. 20 times less than in the previous state-of-the-art. Subsequently, the bio-microfluidic platform was optimized in terms of cost, electrical signal processing and sensitivity to colour variation, yielding 160% improvement of colorimetric AuNPs analysis. Planar microlenses were incorporated to converge light into the sample and then to the output fibre core increasing 6 times the signal-to-losses ratio. The optimized platform enabled detection of single nucleotide polymorphism related with obesity risk (FTO) using target DNA concentration below the limit of detection of the conventionally used microplate reader (i.e. 15 ng/μl) with 10 times lower solution volume (3 μl). The combination of the unique optical properties of gold nanoprobes with microfluidic platform resulted in sensitive and accurate sensor for single nucleotide polymorphism detection operating using small volumes of solutions and without the need for substrate functionalization or sophisticated instrumentation. Simultaneously, to enable on chip reagents mixing, a PDMS micromixer was developed and optimized for the highest efficiency, low pressure drop and short mixing length. The optimized device shows 80% of mixing efficiency at Re = 0.1 in 2.5 mm long mixer with the pressure drop of 6 Pa, satisfying requirements for the application in the microfluidic platform for DNA analysis.Portuguese Science Foundation - (SFRH/BD/44258/2008), “SMART-EC” projec

Flexible and Stretchable Electronics

Flexible and stretchable electronics are receiving tremendous attention as future electronics due to their flexibility and light weight, especially as applications in wearable electronics. Flexible electronics are usually fabricated on heat sensitive flexible substrates such as plastic, fabric or even paper, while stretchable electronics are usually fabricated from an elastomeric substrate to survive large deformation in their practical application. Therefore, successful fabrication of flexible electronics needs low temperature processable novel materials and a particular processing development because traditional materials and processes are not compatible with flexible/stretchable electronics. Huge technical challenges and opportunities surround these dramatic changes from the perspective of new material design and processing, new fabrication techniques, large deformation mechanics, new application development and so on. Here, we invited talented researchers to join us in this new vital field that holds the potential to reshape our future life, by contributing their words of wisdom from their particular perspective

Graphene-based flexible sensors towards electronic wearables

Flexible electronics and wearable devices have attracted considerable attention because they produce mechanical liberty, in terms of flexibility and stretchability that can enable the possibility of a wide range of new applications. The term “wearable electronics” can be used to define devices that can be worn or mated with the sensed surface to continuously monitor signals without limitations on mechanical deformability of the devices and electronic performance of the functional materials. The use of polymeric substrates or other nonconventional substrates as base materials brings novel functionalities to sensors and other electronic devices in terms of being flexible and light weight. Conductive nanomaterials, such as carbon nanotubes and graphene have been utilized as functional materials for flexible electronics and wearable devices. Graphene has specifically been considered for producing next-generation sensors due to its impressive electrical and mechanical properties and a result, incorporation of flexible substrates and graphene-based nanomaterials has been widely utilized to form versatile flexible sensors and other wearable devices through use of different fabrication processes. Creation of a large-scale, simple, high-resolution and cost-effective technique that overcomes fabrication limitations and supports production of flexible graphene-based sensors with high flexibility and stretch ability is highly demanding. Soft lithography can be merged with a mechanical exfoliation process using adhesive tape followed by transfer printing to form a graphene sensor on a desired final substrate. In situ microfluidic casting of graphene into channels is another promising platform driving the rapid development of flexible graphene sensors and wearable devices with a wide dynamic detection range. Selective coating of graphene-based nanomaterials (e.g. graphene oxide (GO)) on flexible electrode tapes can, because of its flexibility and adhesive features, be used to track relative humidity (RH) variations at the surface of target surfaces. This thesis describes the design and development of flexible and wearable strain, pressure and humidity sensors based on a novel tape-based cost-effective patterning and transferring technique, an in situ microfluidic casting method, and a novel selective coating technique for graphene-based nanomaterials. First of all, we present a tape-based graphene patterning and transferring approach to production of graphene sensors on elastomeric substrates and adhesive tapes. The method utilizes the work of adhesion at the interface between two contacting materials as determined by their surface energies to pattern graphene on PDMS substrate and transfer it onto a target tape. We have achieved patterning and transferring method with the features of high pattern spatial resolution, thickness control, and process simplicity with respect to functional materials and pattern geometries. We have demonstrated the usage of flexible graphene sensors on tape to realize interaction with structures, humans, and plants for real-time monitoring of important signals. Secondly, we present a helical spring-like piezo resistive graphene sensor formed within a microfluidic channel using a unique and easy in situ microfluidic casting method. Because of its helical shape, the sensor exhibits a wide dynamic detection range as well as mechanical flexibility and stretch ability. Finally, we present a flexible GO-based RH sensor on an adhesive polyimide thin film realized by selectively coating and patterning GO at the surface of Au Interdigitated electrodes (IDEs) and subsequently peeling the device from a temporary PDMS film. Real-time monitoring of the water movement inside the plant has been demonstrated by installing GO-based RH sensor at the surfaces of different plant leaves

탄소/에폭시 수리를 위한 복합재 프린터

학위논문(박사)--서울대학교 대학원 :공과대학 기계항공공학부,2020. 2. 안성훈.Carbon-fiber composites are widely used in airplanes, and the development of electric vehicles has spurred demand as interest in light materials has increased concurrently. Thus, researchers have begun to study how users of these products repair them, but the properties of fiber composites make it difficult to measure the level of destruction in repaired areas. The repair process is usually based on hand-lay-up. The success of this method depends on the repairer's proficiency, and it takes much labor and time to cut carbon fibers according to the size and shape of the repair part. Furthermore, the post-curing process also takes a long time, regardless of the size of the repair area. This can lead to a large amount of waste when repairing small components, such as the surfaces of car parts. Another issue is how best to evaluate the repaired area. If monitoring the life cycle or deformation of the component is conducted, even after the repair has been carried it, the user can anticipate and prepare for repairs based on strain sensor data. Studies of large equipment, such as conventional airplanes, and the use of automated tape layering (ATL) to make large carbon composite materials have been actively underway since 2016. However, most previous research has been aimed at producing large carbon-fiber composite materials and reducing the ᅮ waste and labor required for repair processes. However, there are no automated processes for smallscale repairs. Various small devices, from vehicles to mobile phones, use composites and thus require appropriate repair processes. Studies focusing on these issues are still lacking. In this study, we developed a rapid curing carbon-fiber composite printer. This can achieve a uniform fiber composite by automating the fiber laying method. A rapid curing device using Joule heat is used for local repairs. The repair time is reduced by mounting the rapid curing device on the printer. The proposed printing system is validated by comparing the recovery rates of undamaged specimens and double-lap repaired specimens. These repaired samples achieve uniform quality following repeated repair, and are thus superior to conventional hand-lay-up repaired samples. The use of the rapid curing system improved the recovery rate by 93% or more in the double lap test. As mentioned previously, the variables used to describe the repair performance, which may vary depending on the technician's proficiency, are stabilized under our system. The rapid curing is also optimized by mounting a feedback system between the temperature and electric power. This achieves uniform recovery rates, regardless of user proficiency. Non-destructive testing is also possible if we attach highly sensitive nanoparticle sensors to the device. The quality of the repair is assessed based on the life cycle and deformation of adhesive repair patches, which are evaluated using the proposed sensors. In this study, we propose the use of a rapid curing carbon composite printer and nanoparticle sensors. We expect that the composite printer developed in our research can be used to support the development of carbon composite applications in industries such as electric vehicles and airplanes.탄소 섬유 복합재의 수요는 비행기 산업 및 풍력 발전 산업 등에서 많이 사용되어 왔으며, 전기차의 발전으로 인해 경량소재에 대한 관심 또한 증가하면서 더욱 많은 수요가 발생하였다. 이에 따라 이 제품들을 사용하는 사용자들의 수리방법에 대한 연구가 진행되어왔으며, 섬유 복합재의 특성상 수리된 부위의 파괴수준을 측정하기 어렵고, 이를 확인한 후에도 수리과정이 작업자의 손을 이용한 작업이 주된 방법이다. 이 방법은 수리자의 숙련도에 크게 수리의 성능이 좌우되는 방법이며, 수리부위의 크기와 형태에 따라 탄소 섬유를 재단하는데 큰 노동과 시간이 들어간다. 또한 복합재의 다른 특성인 후경화 과정은 수리과정에서 긴 시간을 요구하며, 이는 수리 부위의 크기와 상관없이 긴 시간이 걸리기 때문에 자동차 부분 파손 혹은 휴대폰 외관 수리와 같은 작은 파트를 수리하는 부분에 있어 큰 낭비가 될 수 있다. 수리를 완료한 이후에도 이 수리부의 수명이나 변형을 측정함으로써, 사용자가 파손을 예측하고 대비하고 정도에 따라 수리과정을 준비할 방법 또한 필요하다. 본 연구에서는 위와 같은 문제들에 대하여 사람의 손으로 진행해야 하는 부분을 자동화함으로써 변수를 통합 및 안정화하고, 긴 시간을 차지하는 후경화를 국지적 주울열을 통한 급속 경화 장치를 추가함으로써 급속 경화 탄소 섬유 복합재 프린터를 개발하였다. 기존의 비행기나 대형 탄소복합재를 만들기 위한 Automated tape laying (ATL) 과 같은 대형 장비들에 대한 연구들이 2016 부터 활발히 진행되었으나, 기존 연구의 대부분은 대형 탄소 섬유 복합재를 제작하는 것을 목적으로 진행하고 있어, 후경화의 단축에 대한 연구수행과 소규모성의 수리를 위한 자동화 공정에 대한 연구는 여전히 부족한 실정이다. 또한 본 연구의 국지적 수리에 적합한 주울열을 통한 급속 경화 장치가 적용된 사례는 없다. 이와 같이 본 연구에서 제안된 프린팅 시스템을 이용하여 양면 접착 방식의 수리 시편을 만들어 기존 미파괴 시편과의 파단강도에 따른 비율을 회복률이라고 정의하였다. 또한 실험을 통해 회복률을 확인하였고, 프린팅을 통한 수리 시편은 인장강도 기준으로 80% 이상 수준을 달성하였고 급속 경화 시스템을 추가한 시편의 경우는 짧은 구간에서 더 높은 접착력을 보이면서 93%이상 회복률로 향상되었다. 또한 앞서 제시한 바와 같이 수리자의 숙련도에 따라 변경될 수 있는 수리 성능에 대한 변수를 규격화 하였으며, 온도와 전력량 간의 피드백 시스템을 형성하여 급속 경화 또한 최적화함으로써 사용자의 숙련도와 상관없이 균일한 회복률을 얻을 수 있는 효과를 얻었고 이에 접착 수리 패치의 수명과 대변형과 같은 수리파손 예방을 위한 나노입자 센서를 부착하고 무선통신 시스템을 적용함으로써 비파괴 검사 또한 진행할 수 있도록 하였다. 본 연구에서 제안된 급속 경화 탄소 복합재 프린터와 이를 검사할 수 있는 시스템의 원리를 응용한 기술은 발전될 탄소 섬유를 이용한 전기차 혹은 휴대기기 시장 등 산업적 응용 분야 확장에 기여할 것으로 기대된다.1 CHAPTER 1. INTRODUCTION 1 1.1 OVERVIEW 1 1.2 CARBON FIBER REINFORCED PLASTIC (CFRP) 5 1.3 CFRP REPAIR 5 1.4 THE GOAL OF THIS RESEARCH 7 1.5 OUTLINE OF DISSERTATION 9 2 CHAPTER 2. BACKGROUND 11 2.1 DEMAND FOR CFRP 11 2.2 BONDED PATCH REPAIR 13 2.3 STRUCTURAL HEALTH MONITORING (SHM) 19 3 CHAPTER 3. DESIGN AND FABRICATION 21 3.1 DIRECT CARBON PRINTING SYSTEM 21 3.1.1 Overview of printing system 21 3.1.2 Fiber feeding component 26 3.1.3 Epoxy feeding component 30 3.2 RAPID CURING SYSTEM 32 3.2.1 Overview of rapid curing process 32 3.2.2 Modeling for rapid curing 33 3.2.3 Joule heating module 39 3.2.4 Electric-Thermal feedback module 44 3.3 HIGHLY SENSITIVE SENSOR PATCH FOR SHM 48 3.3.1 Aerodynamically focused nanoparticle (AFN) printing 48 3.3.2 Highly sensitive strain sensor 53 3.3.3 Design of sensor patch and communication system 57 4 CHAPTER 4. EVALUATION 64 4.1 EVALUATION OF PRINTED SAMPLE 64 4.2 EVALUATION OF DEGREE OF CURING VIA RAPID CURING 77 4.3 EVALUATION OF SHM VIA COMMUNICATION SYSTEM 84 5 CHAPTER 5. CONCLUSION 89 BIBLIOGRAPHY 91 요약 (국문초록) 99Docto

The impact of printed electronics on product design

Printed electronics (PE) is a disruptive but growing technology that is beginning to integrate its way into viable applications for product design. However, the potential for future impact of the technology on product design and the designer s role and contribution to this has yet to be established. Interest is increasing in the potential for product designers to explore and exploit this technology. Technologies can be seen as being disruptive from both a business, and an adoption point of view. For a business, changing from one technology to another or incorporating a new technology and its production processes can be difficult if they already have their suppliers established and existing relationships in place. Understanding and adopting a new technology can be challenging for a business and individuals working within an established industry as it can cause many questions to be raised around its performance, and direct comparison with the technology they already have in place. However, there have been many technologies that could be seen as disruptive in the past, as they offered an alternative way of working or method of manufacture, such as Bluetooth, 3D printing, and automation (manufacturing/assembly/finishing), etc., and their success has been dictated by individual s perception and adoption of the technology, with their ability to see the worth and potential in the technology. Cost comparison is also an important aspect for a business to consider when choosing whether to change to a new technology or to remain with their existing technology, as changing can disrupt the manufacturing line assembly of a product, and direct cost comparisons of components themselves, such as the cost of buying silicon components in bulk verses printing the components. The new technology needs to offer something different to a product to be worth implementing it in a product, such as its flexible form or lightweight properties of printed electronics being of benefit to the product over what a silicon electronic component/circuit could offer (restricted to rigid circuit boards), the functionality/performance of the components themselves also need to be considered. Performance, availability and maturity of the technology are some of the essential aspects to consider when incorporating a new technology into a product and these can be evaluated using a Technology Readiness Level (TRL) scale. Interest in the stage of development for a technology lies not only with designers; industry and academia also contribute to knowledge by playing a central role in the process of determining a TRL scale that is universally recognised. However, a TRL separation issue occurs between academia (often the technology only reaching an experimental proof of concept stage, a lower number on the TRL scale indicating that the technology is at an early stage of development) and industry (not considering technology for commercialisation until it reaches a stage where there is a demonstration of pre-production capability validated on economic runs, a much higher number on the TRL scale - indicating that the technology is at a much more advanced stage of development). The aim of this doctoral research was to explore the contribution of PE to product design. The researcher experienced the scientific development of the technology first-hand, and undertook a literature review that covered three main topics: 1) printed electronics (the technology itself), 2) impact (approaches to assessing impact and methods of judging new technology) because together they will identify the state of the art of printed electronics technology, and 3) education - educational theories/methods for designers - studying how designers learn, explore different methods in educating them about new technologies, and start to find appropriate methods for educating them about printed electronics technology. A knowledge framework for PE technology was generated and utilised to produce a taxonomy and TRL scale for PE and confirmed by PE expert interview. Existing case studies in which PE technology had been presented to student designers were investigated through interviews with participants from academia and industry to solicit perception and opinions on approaches for the effective communication of PE knowledge to student designers within an educational environment. The findings were interpreted using thematic analysis and, after comparing the data, three main themes identified: technical constraints, designer s perspective, and what a designer is required to do. The findings from the research were combined to create an educational approach for knowledge transfer aimed specifically at meeting the needs of product designers. This resulted in the need for PE technology to be translated into both a visual and written format to create structure and direct links between the technological elements and their form and function in order to facilitate understanding by designers. Conclusions from the research indicate that the translation of this technology into an appropriate design language will equip designers with accessible fundamental knowledge on PE technology (i.e. electrical components: form, function, and area of the technology), which will allow informed decisions to be made about how PE can be used and to utilise its benefits in the design of products. The capabilities and properties of this technology, when paired with product design practice, has the capacity to transform the designs of future products in terms of form/functionality and prevailing/views towards design approaches with electronics. If exposed to a variety of PE elements ranging across different TRLs, designers have the capacity to bridge the TRL separation issue (the gap between academia and industry) through their ability to create design solutions for an end user and provide a commercial application for the technology

Liquid Metal Printing with Scanning Probe Lithography for Printed Electronics

In den letzten Jahren hat das „Internet der Dinge“ (Englisch Internet of Things, abgekürzt IoT), das auch als Internet of Everything (Deutsch frei „Internet von Allem“) bezeichnet wird, mit dem Aufkommen der „Industrie 4.0“ einen Strom innovativer und intelligenter sensorgestützter Elektronik der neuen Generation in den Alltag gebracht. Dies erfordert auch die Herstellung einer riesigen Anzahl von elektronischen Bauteilen, einschließlich Sensoren, Aktoren und anderen Komponenten. Gleichzeitig ist die herkömmliche Elektronikfertigung zu einem hochkomplexen und investitionsintensiven Prozess geworden. In dem Maße, wie die Zahl der elektronischen Bauteile und die Nachfrage nach neuen, fortschrittlicheren elektronischen Bauteilen zunimmt, steigt auch die Notwendigkeit, effizientere und nachhaltigere Wege zur Herstellung dieser Bauteile zu finden. Die gedruckte Elektronik ist ein wachsender Markt, der diese Nachfrage befriedigen und die Zukunft der Herstellung von elektronischen Geräten neu gestalten könnte. Sie erlaubt eine einfache und kostengünstige Produktion und ermöglicht die Herstellung von Geräten auf Papier- oder Kunststoffsubstraten. Für die Herstellung gibt es dabei eine Vielzahl von Methoden. Techniken auf der Grundlage der Rastersondenlithografie waren dabei schon immer Teil der gedruckten Elektronik und haben zu Innovationen in diesem Bereich geführt. Obwohl die Technologie noch jung ist und der derzeitige Stand der gedruckten Elektronik im industriellen Maßstab, wie z. B. die Herstellung kompletter integrierter Schaltkreise, stark limitiert ist, sind die potenziellen Anwendungen enorm. Im Mittelpunkt der Entwicklung gedruckter elektronischer Schaltungen steht der Druck leitfähiger und anderer funktionaler Materialien. Die meisten der derzeit verfügbaren Arbeiten haben sich dabei auf die Verwendung von Tinten auf Nanopartikelbasis konzentriert. Die Herstellungsschritte auf der Grundlage von Tinten auf Nanopartikelbasis sind komplizierte Prozesse, da sie das Ausglühen (Englisch Annealing) und weitere Nachbearbeitungsschritte umfassen, um die gedruckten Muster leitfähig zu machen. Die Verwendung von Gallium-basierten, bei/nahe Raumtemperatur flüssigen Metallen und deren direktes Schreiben für vollständig gedruckte Elektronik ist immer noch ungewöhnlich, da die Kombination aus dem Vorhandensein einer Oxidschicht, hohen Oberflächenspannungen und Viskosität ihre Handhabung erschwert. Zu diesem Zweck zielt diese Arbeit darauf ab, Methoden zum Drucken von Materialien, einschließlich Flüssigmetallen, zu entwickeln, die mit den verfügbaren Druckmethoden nicht oder nur schwer gedruckt werden können und diese Methoden zur Herstellung vollständig gedruckter elektronischer Bauteile zu verwenden. Weiter werden Lösungen für Probleme während des Druckprozesses untersucht, wie z. B. die Haftung der Tinte auf dem Substrat und andere abscheidungsrelevante Aspekte. Es wird auch versucht, wissenschaftliche Fragen zur Stabilität von gedruckten elektronischen Bauelementen auf Flüssigmetallbasis zu beantworten. Im Rahmen der vorliegenden Arbeit wurde eine auf Glaskapillaren basierenden Direktschreibmethode für das Drucken von Flüssigmetallen, hier Galinstan, entwickelt. Die Methode wurde auf zwei unterschiedlichen Wegen implementiert: Einmal in einer „Hochleistungsversion“, basierend auf einem angepassten Nanolithographiegerät, aber ebenfalls in einer hochflexiblen, auf Mikromanipulatoren basierenden Version. Dieser Aufbau erlaubt einen on-the-fly („im Fluge“) kapillarbasierten Druck auf einer breiten Palette von Geometrien, wie am Beispiel von vertikalen, vertieften Oberflächen sowie gestapelten 3D-Gerüsten als schwer zugängliche Oberflächen gezeigt wird. Die Arbeit erkundet den potenziellen Einsatz dieser Methode für die Herstellung von vollständig gedruckten durch Flüssigmetall ermöglichten Bauteilen, einschließlich Widerständen, Mikroheizer, p-n-Dioden und Feldeffekttransistoren. Alle diese elektronischen Bauelemente werden ausführlich charakterisiert. Die hergestellten Mikroheizerstrukturen werden für temperaturgeschaltete Mikroventile eingesetzt, um den Flüssigkeitsstrom in einem Mikrokanal zu kontrollieren. Diese Demonstration und die einfache Herstellung zeigt, dass das Konzept auch auf andere Anwendungen, wie z.B. die bedarfsgerechte Herstellung von Mikroheizern für in-situ Rasterelektronenmikroskop-Experimente, ausgeweitet werden kann. Darüber hinaus zeigt diese Arbeit, wie PMMA-Verkapselung als effektive Barriere gegen Sauerstoff und Feuchtigkeit fungiert und zusätzlich als brauchbarer mechanischer Schutz der auf Flüssigmetall basierenden gedruckten elektronischen Bauteile wirken kann. Insgesamt zeigen der alleinstehende, integrierte Herstellungsablauf und die Funktionalität der Geräte, dass das Potenzial des Flüssigmetall-Drucks in der gedruckten Elektronik viel größer ist als einzig die Verwendung zur Verbindung konventioneller elektronischer Bauteile. Neben der Entwicklung von Druckverfahren und der Herstellung elektronischer Bauteile befasst sich die Arbeit auch mit der Korrosion und der zusätzlichen Legierung von konventionellen Metallelektroden in Kontakt mit Flüssigmetallen, welche die Stabilität der Bauteil beinträchtigen könnten. Zu diesem Zweck wurde eine korrelierte Materialinteraktionsstudie von gedruckten Galinstan- und Goldelektroden durchgeführt. Durch die kombinierte Anwendung von optischer Mikroskopie, vertikaler Rasterinterferometrie, Rasterelektronenmikroskopie, Röntgenphotonenspektroskopie und Rasterkraftmikroskopie konnte der Ausbreitungsprozess von Flüssigmetalllinien auf Goldfilmen eingehend charakterisiert werden. Diese Studie zeigt eine unterschiedliche Ausbreitung der verschiedenen Komponenten des Flüssigmetalls sowie die Bildung von intermetallischen Nanostrukturen auf der umgebenden Goldfilmoberfläche. Auf der Grundlage der erhaltenen zeitabhängigen, korrelierten Charakterisierungsergebnisse wird ein Modell für den Ausbreitungsprozess vorgeschlagen, das auf dem Eindringen des Flüssigmetalls in den Goldfilm basiert. Um eine ergänzende Perspektive auf die interne Nanostruktur zu erhalten, wurde die Röntgen-Nanotomographie eingesetzt, um die Verteilung von Gold, Galinstan und intermetallischen Phasen in einem in das Flüssigmetall getauchten Golddraht zu untersuchen. Schlussendlich werden Langzeitmessungen des Widerstands an Flüssigmetallleitungen, die Goldelektroden verbinden, durchgeführt, was dazu beiträgt, die Auswirkungen von Materialwechselwirkungen auf elektronische Anwendungen zu bewerten