삽입형 의료 장치 및 광전자 소자를 위한 차세대 유연 물질의 설계와 제작

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부 에너지환경화학융합기술전공, 2017. 2. 김대형.Soft electronics provide new opportunities on biomedical devices and optoelectronic devices since they offer flexible and conformable mechanical properties. Compared to commercialized rigid electronics, the soft electronics enables more accurate sensing from the curvilinear biological interface and tunable light incidence for optoelectronics. In this thesis, fabrication and application of soft medical devices and unconventional optoelectronic devices are developed based on the design and synthesis of bioresorbable and perovskite materials. Firstly, soft bioresorbable medical devices are designed and fabricated, which provide novel therapeutic guideline to overcome many challenges remaining for the treatment of glioblastoma. The integrated bioresorbable devices are composed of wireless heater, wireless temperature sensor and synthesized bioresorbable drug reservoir conformally adhered to the brain tissue provides localized, highly penetrative and controllable intracranial drug delivery. Based on the fabrication technique of bioresorbable materials, transient memory system is proposed and developed, which shows fast and complete chemical destruction of stored data by wide-range optical stimulation. The system can be established by the integration of transient ultrathin resistive random access memory (RRAM) with multi-dye-sensitized upconverting nanoparticles (UCNPs) and provides new opportunities in mobile and defense application. The final goal of this study is high-definition patterning of inorganic-organic hybrid perovskite thin films which have attracted great attention since it is regarded as an alternative to silicon in the optoelectronic devices. A new method so called Spin-on-patterning (SoP) enables the patterning of perovskite thin film which has hardly been accomplished due to their extreme instability in solvents like bioresorbable materials. The patterned perovskite photodiode is fabricated and has potential for future ultrathin image sensor array.Chapter 1. Introduction 1 1.1 Soft electronics 1 1.2 Soft bioresorbable electronics 7 1.3 Soft perovskite electronics 15 1.4 References 16 Chapter 2. Design, synthesis and fabrication of bioresorbable electronic patch for glioblastoma 24 2.1 Introduction 25 2.2 Result and Discussion 27 2.3 Conclusion 48 2.4 Experimental 49 2.5 References 58 Chapter 3. Integration of destructible resistive memory and multi-dye-sensitized upconverting nanoparticles for information security application 64 3.1 Introduction 64 3.2 Result and Discussion 67 3.3 Conclusion 99 3.4 Experimental 100 3.5 References 112 Chapter 4. High-resolution spin-on-patterning of perovskite thin films for optoelectronic device array 121 3.1 Introduction 121 3.2 Result and Discussion 124 3.3 Conclusion 144 3.4 Experimental 145 3.5 References 150 Bibliography 155 국문 초록 (Abstract in Korean) 157Docto

Design and implementation of a light-based IoT (LIoT) node using printed electronics

Abstract. The recent exponential growth of new radio frequency (RF) based applications such as internet of things (IoT) technology is creating a huge bandwidth demand in the already congested RF spectrum. Meanwhile, visible light communication (VLC) is emerging as a technology which can be used as an alternative wireless communications solution which makes no use of the radio spectrum. In addition, continuously powering up the massively deployed IoT nodes is becoming a challenge when it comes to maintenance costs. Development of energy autonomous IoT nodes would certainly assist to solve the energy challenge. Previous work shows that renewable energy sources can be utilized to address the energy requirement of IoT nodes. Under this context, we have developed a light-based energy autonomous IoT (LIoT) prototype. This thesis presents a feasibility study and proof of concept of LIoT, including design, implementation and validation of LIoT nodes and a transmitter unit. Furthermore, the ability of multiuser communication using VLC as well as indoor light-based energy harvesting were demonstrated and tested in this thesis. To make the concept of LIoT more attractive from an implementation standpoint, and to create a future-looking solution, printed electronics (PE) technology was used as a part of the implementation. Two key components of the prototype were based on PE technology, photovoltaic cells used to harvest energy, and displays used to exhibit information transmitted to the LIoT node. In the future, when PE technology becomes more mature, very low-cost, small form-factor and environmentally friendly LIoT nodes could be implemented on thin substrates. A wide array of possible applications can be created combining the concept of light-based IoT with printed electronics. The proposed LIoT concept shows great promise as an enabling technology for 6G

Smart Materials and Devices for Energy Harvesting

This book is devoted to energy harvesting from smart materials and devices. It focusses on the latest available techniques recently published by researchers all over the world. Energy Harvesting allows otherwise wasted environmental energy to be converted into electric energy, such as vibrations, wind and solar energy. It is a common experience that the limiting factor for wearable electronics, such as smartphones or wearable bands, or for wireless sensors in harsh environments, is the finite energy stored in onboard batteries. Therefore, the answer to the battery “charge or change” issue is energy harvesting because it converts the energy in the precise location where it is needed. In order to achieve this, suitable smart materials are needed, such as piezoelectrics or magnetostrictives. Moreover, energy harvesting may also be exploited for other crucial applications, such as for the powering of implantable medical/sensing devices for humans and animals. Therefore, energy harvesting from smart materials will become increasingly important in the future. This book provides a broad perspective on this topic for researchers and readers with both physics and engineering backgrounds

Inorganic and Organic Photovoltaic Materials for Powering Electrochromic Systems

abstract: ABSTRACT Autonomous smart windows may be integrated with a stack of active components, such as electrochromic devices, to modulate the opacity/transparency by an applied voltage. Here, we describe the processing and performance of two classes of visibly-transparent photovoltaic materials, namely inorganic (ZnO thin film) and fully organic (PCDTBT:PC70BM), for integration with electrochromic stacks. Sputtered ZnO (2% Mn) films on ITO, with transparency in the visible range, were used to fabricate metal-semiconductor (MS), metal-insulator-semiconductor (MIS), and p-i-n heterojunction devices, and their photovoltaic conversion under ultraviolet (UV) illumination was evaluated with and without oxygen plasma-treated surface electrodes (Au, Ag, Al, and Ti/Ag). The MS Schottky parameters were fitted against the generalized Bardeen model to obtain the density of interface states (Dit ≈ 8.0×1011 eV−1cm−2) and neutral level (Eo ≈ -5.2 eV). These devices exhibited photoconductive behavior at λ = 365 nm, and low-noise Ag-ZnO detectors exhibited responsivity (R) and photoconductive gain (G) of 1.93×10−4 A/W and 6.57×10−4, respectively. Confirmed via matched-pair analysis, post-metallization, oxygen plasma treatment of Ag and Ti/Ag electrodes resulted in increased Schottky barrier heights, which maximized with a 2 nm SiO2 electron blocking layer (EBL), coupled with the suppression of recombination at the metal/semiconductor interface and blocking of majority carriers. For interdigitated devices under monochromatic UV-C illumination, the open-circuit voltage (Voc) was 1.2 V and short circuit current density (Jsc), due to minority carrier tunneling, was 0.68 mA/cm2. A fully organic bulk heterojunction photovoltaic device, composed of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyli2’,1’,3’-benzothiadiazole)]:phenyl-C71-butyric-acidmethyl (PCDTBT:PC70BM), with corresponding electron and hole transport layers, i.e., LiF with Al contact and conducting/non-conducting (nc) PEDOT:PSS (with ITO/PET or Ag nanowire/PDMS contacts; the illuminating side), respectively, was developed. The PCDTBT/PC70BM/PEDOT:PSS(nc)/ITO/PET stack exhibited the highest performance: power conversion efficiency (PCE) ≈ 3%, Voc = 0.9V, and Jsc ≈ 10-15 mA/cm2. These stacks exhibited high visible range transparency, and provided the requisite power for a switchable electrochromic stack having an inkjet-printed, optically-active layer of tungsten trioxide (WO3), peroxo-tungstic acid dihydrate, and titania (TiO2) nano-particle-based blend. The electrochromic stacks (i.e., PET/ITO/LiClO4/WO3 on ITO/PET and Ag nanowire/PDMS substrates) exhibited optical switching under external bias from the PV stack (or an electrical outlet), with 7 s coloration time, 8 s bleaching time, and 0.36-0.75 optical modulation at λ = 525 nm. The devices were paired using an Internet of Things controller that enabled wireless switching.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Aspects of Nanoelectronics in Materials Development

Nanotechnology is an enabling technology that potentially impacts all aspects of the chip-making practice from materials to devices, to circuits, and to system-level architecture. Nanoelectronics is an interdisciplinary division which refers to the use of nanotechnology in electronic components. The materials and devices used in nanoelectronics are so small that the interatomic interactions and quantum mechanical properties of such materials need to be studied extensively. Various electronic devices manufactured at nanoscale have been established: devices having negative differential resistance, switches which can be electrically configured, tunneling junctions, carbon nanotube (CNT) transistor, and unimolecular transistor. Some devices have also been linked together to form circuits proficient of performing functions such as logic functions and basic memory. Some of the widely used materials in nanoelectronics include zero-dimensional materials like quantum dots; one-dimensional materials like nanotubes and nanowires; nanoclusters and nanocomposites; carbon-based materials like carbon nanotubes (CNTs), fullerenes and graphene; etc. Plastic C nanoelectronics is also a prominent research area with collaboration between the materials science, chemistry, physics, nanotechnology, and engineering communities. As one of the most promising contenders, C nanostructures, either 2D graphene or quasi-1D CNTs, have unlocked entirely new standpoints concerning the C-based electronics. This chapter focuses on the approaches of nanotechnology toward nanoelectronics, materials used in nanoelectronics and the applications of nanoelectronics related to carbon-based materials in the field of thin-film transistors, printed electronics (PE), artificial skin and muscle, wearable electronics, flexible gas sensors, multifunctional and responsive elastomers, and plastic solar panels

Roadmap on energy harvesting materials

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere

Antennas and Propagation

This Special Issue gathers topics of utmost interest in the field of antennas and propagation, such as: new directions and challenges in antenna design and propagation; innovative antenna technologies for space applications; metamaterial, metasurface and other periodic structures; antennas for 5G; electromagnetic field measurements and remote sensing applications

Autonomous Sensing Nodes for IoT Applications

The present doctoral thesis fits into the energy harvesting framework, presenting the development of low-power nodes compliant with the energy autonomy requirement, and sharing common technologies and architectures, but based on different energy sources and sensing mechanisms. The adopted approach is aimed at evaluating multiple aspects of the system in its entirety (i.e., the energy harvesting mechanism, the choice of the harvester, the study of the sensing process, the selection of the electronic devices for processing, acquisition and measurement, the electronic design, the microcontroller unit (MCU) programming techniques), accounting for very challenging constraints as the low amounts of harvested power (i.e., [μW, mW] range), the careful management of the available energy, the coexistence of sensing and radio transmitting features with ultra-low power requirements. Commercial sensors are mainly used to meet the cost-effectiveness and the large-scale reproducibility requirements, however also customized sensors for a specific application (soil moisture measurement), together with appropriate characterization and reading circuits, are also presented. Two different strategies have been pursued which led to the development of two types of sensor nodes, which are referred to as 'sensor tags' and 'self-sufficient sensor nodes'. The first term refers to completely passive sensor nodes without an on-board battery as storage element and which operate only in the presence of the energy source, provisioning energy from it. In this thesis, an RFID (Radio Frequency Identification) sensor tag for soil moisture monitoring powered by the impinging electromagnetic field is presented. The second term identifies sensor nodes equipped with a battery rechargeable through energy scavenging and working as a secondary reserve in case of absence of the primary energy source. In this thesis, quasi-real-time multi-purpose monitoring LoRaWAN nodes harvesting energy from thermoelectricity, diffused solar light, indoor white light, and artificial colored light are presented

Smart Fabric sensors for foot motion monitoring

Smart Fabrics or fabrics that have the characteristics of sensors are a wide and emerging field of study. This thesis summarizes an investigation into the development of fabric sensors for use in sensorized socks that can be used to gather real time information about the foot such as gait features. Conventional technologies usually provide 2D information about the foot. Sensorized socks are able to provide angular data in which foot angles are correlated to the output from the sensor enabling 3D monitoring of foot position. Current angle detection mechanisms are mainly heavy and cumbersome; the sensorized socks are not only portable but also non-invasive to the subject who wears them. The incorporation of wireless features into the sensorized socks enabled a remote monitoring of the foot

The 2021 flexible and printed electronics roadmap

This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies