본문 바로가기 주메뉴 바로가기
22대 대한민국 국회 국회정보길라잡이 국회의원검색
회원가입 로그인
HOME

정보검색

소장정보 검색

국회도서관 홈으로 정보검색 소장정보 검색

결과 내 검색

동의어 포함

고급검색

인명/단체명

저자정보 상세정보
인명/단체명을 입력하세요.

키워드

  • 대표어

  • 외국어

-

목차보기

Title Page

Abstract

Contents

Chapter 1. Introduction 13

1.1. Liquid metals 13

1.1.1. Types of liquid metals 13

1.1.2. Gallium-based liquid metals 14

1.2. Liquid metal marbles 19

1.2.1. Preparation methods of liquid metal marbles 19

1.2.2. Applications of liquid metal marbles 22

1.3. Liquid metal actuators 24

Chapter 2. Lorentz force-driven actuator with liquid metal marbles in dry environments 26

2.1. Introduction 26

2.2. Experimental section 28

2.2.1. Materials 28

2.2.2. Preparation of liquid metal marbles 28

2.2.3. Fabrication of Lorentz force-driven liquid metal marble actuators 28

2.2.4. Sample Preparation for SEM 28

2.2.5. Resistance of the LMMs measurement 29

2.3. Results and Discussion 31

2.3.1. Liquid metal marbles 31

2.3.2. Lorentz force-driven actuator with liquid metal marbles 37

2.4. Conclusion 42

References 44

List of Tables

Table 1.1. Physical properties of water and LMs. Reproduced from Ref. [1], [2], [7], and [8]. 16

List of Figures

Figure 1.1. Schematic image of types of liquid metals 13

Figure 1.2. Representative images of LMs, which are mercury (Hg), cesium (Cs), gallium (Ga), and eutectic gallium indium (EGaIn). 14

Figure 1.3. Native surface oxide skin of Gallium-based LMs. a) Predicted dominance of metal oxides based on Gibbs free energy of formation. Oxides positioned to the right of the red dashed line are... 17

Figure 1.4. Photographs of direct printed LM 3D structures. These remarkable, self-supporting 3D structures made of LMs can be achieved through the utilization of the inherent oxide skin at room... 18

Figure 1.5. Photographs of 'liquid metal marbles(LMMs)' and 'liquid marble.' a), b), and c) are Scanning Electron Microscope (SEM) images that depict a LMM in different configurations: a) and b)... 21

Figure 1.6. Schematic illustrations of the preparation methods of LMMs. a) Rolling method; LMMs are prepared by rolling LM droplets on a powder (particle) bed. b) presents a conceptual schematic... 21

Figure 1.7. Diverse applications of LMMs. a) and b) showcase actuator applications: (a) water-driven micromotor utilizing LMMs, and (b) actuator functioning through the photochemically induced... 23

Figure 1.8. Type of liquid metal actuators with various actuation mechanisms. The mechanisms are a) interfacial tension modulation by electrochemical oxidation and reduction, b) continuous electrowetting,... 23

Figure 2.1. Photograph of a tungsten powder bed utilized in the fabrication of LMMs. The blocking walls consist of cut-glass substrates positioned with a 4 cm gap between them. 30

Figure 2.2. Photograph of the set-up for electrical property measurement. LMM is placed between two copper electrodes (with a spacing of 0.1 mm) on top. Transparent blocking walls are used to ensure... 30

Figure 2.3. a) Schematic comparison between a liquid metal marble and a liquid metal droplet. b) Photograph captured from a video showing the fabrication of LMMs and the subsequent transfer of the... 32

Figure 2.4. Photograph of LMMs coated with various material powders. The panel (a) shows the samples, including rolled bare LM, tungsten, copper, silica, and copper NPs coated LMMs. The panels... 33

Figure 2.5. Photographs of LMMs coverage difference according to rolling times. 33

Figure 2.6. Scanning electron microscope (SEM) images of tungsten coated LMM. The panel of (b) and (c) show the magnified views of the image in panel (a). 34

Figure 2.7. Photograph captured from a video displaying the effectiveness of LMMs in preventing the adhesion of LM droplets to glass surfaces. The presence of coating powder enables the LMM to roll... 35

Figure 2.8. Photographs about a) the anti-corrosion test and b) the stability test in HCl solvent. 36

Figure 2.9. The plot for the electrical resistances of the LM droplets and LMMs measured by the two-probe method. 37

Figure 2.10. Schematic illustration of Lorentz force-driven actuator with LM system. The blue, red, and white arrows mean the directions of current, Lorentz force, and magnetic field, respectively. The... 38

Figure 2.11. Schematic illustration depicting the existing forces in the system acting on the static LMM. 38

Figure 2.12. a) Schematic illustration of the enclosed mold, comprising the upper and bottom parts made of PMMA, copper electrodes, and the LMM. b) through e) show photographs of individual... 41

Figure 2.13. Images captured from a video showing the movement of the LM under the influence of Lorentz force. In (a) and (b), the current direction is reversed, while the other conditions remain the same. 41

초록보기

 Liquid metal (LM) refers to a unique class of metallic materials that possess the remarkable property of being in a liquid state at room temperature or slightly above. Unlike conventional metals, which are typically solid at room temperature, LMs are characterized by their low melting points, enabling them to flow and deform readily. Such a unique characteristic makes them attractive candidates for a variety of applications such as deformable electronics, bio-medical technologies, sensors, actuators, etc. Among diverse classes of LMs, gallium, and its alloys have risen to prominence in recent years due to their unusual properties arising from the high degree of covalent bonding, which results in it staying in the liquid state over a range of 2000 ℃ and a low vapor pressure below 1500 ℃. Accordingly, in recent decades, many researchers have intensively studied this class of LMs for a fundamental understanding of materials' properties as well as their practical applications. However, these materials still suffer the issues of high corrosiveness and strong adhesion to nearly every surface, deteriorating their long-term stability.

Liquid metal-based actuators are a type of actuator that utilizes the unique properties of LMs to create mechanical movements. These actuators offer several advantages over traditional actuators, including high flexibility, low voltage operation, and the ability to change shape and adapt to different environments. This thesis presents the preparation of liquid metal marbles (LMMs) and their use as active moving parts in Lorentz force-driven actuators.

LMM refers to a droplet of LMs that maintains its shape by encapsulation with coating layers that prevents it from spreading or merging with its surroundings. To formulate the LMMs, a variety of coating materials, including tungsten, copper, and silica particles, were investigated, and the microstructural characteristics of the formulated LMMs were characterized. These LMMs exhibited significantly improved corrosion stability compared with bare LM droplets. Moreover, the electrical resistances of the LMMs were similar to or slightly higher than that observed in bare LM droplets with oxide skins. Such high stability and electrical properties of the LMMs allowed us to use them as an active material in a Lorentz force-driven actuator under a dry environment, in which the actuation of the LMMs was investigated under the constant magnetic field. The actuation of the LMMs was well operated by applying electrical powers, of which the minimum for driving the actuation was found to decrease with increasing the volumes of the LMMs. This can be attributable to the larger contact areas to electrodes with larger LMMs, which is further supported by the fact that the LMMs with a flatter shape were actuated with lower electrical power than spherical LMMs. These Lorentz force-based dry actuators of LMMs can be operated by an electrical power of less than 3 W, which is an order of magnitude lower than the required powers of the reported LM-based actuators. This study offers a new avenue to improve the versatility and sustainability of LMs, shedding light on the long-term use of these promising materials in technological devices. Moreover, the demonstration of the Lorentz force-based actuator using LMMs, especially under dry environments, will expand the applicability of LMs.

추천서가 (다양한 추천 자료를 만나보세요)

권호기사보기

권호기사 목록 테이블로 기사명, 저자명, 페이지, 원문, 기사목차 순으로 되어있습니다.
기사명 저자명 페이지 원문 기사목차

권호

기사명 원문보기 기사목차
닫기