Engineering Fusogenic Extracellular Vesicles for Enhanced Cytosolic Delivery and Immunogenic Cancer Therapy

Yeong Ha Hwang 고려대학교 KU-KIST융합대학원 2026 국내박사

Intercellular communication occurs not only through direct cell–cell contact or secreted signals such as cytokines but also via nanoscale vesicles known as extracellular vesicles (EVs). EVs carry membrane proteins derived from the plasma membrane, cytosolic proteins, and various nucleic acids, enabling them to play an important role in the transmission of physiological and pathological information. In this study, we explored strategies to enhance the delivery efficiency of EV-encapsulated cargos through EV engineering, as well as approaches that employ virus-derived fusogenic proteins to improve cytosolic delivery. [Paper Ⅰ] Efforts to utilize EV as therapeutic delivery vehicles have steadily progressed, and recent advances in genetic engineering have enabled the active loading of functional genetic cargos such as mRNA and transcription factors into EVs. However, once internalized by recipient cells, these cargos are frequently sequestered in endosomes and subsequently degraded through lysosomal pathways, leading to substantial loss and markedly reduced delivery efficiency. This challenge has highlighted the need for strategies that enable EVs to achieve endosomal–lysosomal degradation escape. Approaches to express virus-derived fusogenic proteins, such as VSV-G, on EV membranes have therefore been explored. In this work, we review diverse endosomal–lysosomal escape strategies developed to date, the analytical methods used to quantitatively assess their effectiveness, and how these approaches may be applied to the development of EV-based therapeutics. [Paper Ⅱ] Building upon these insights, this study further designed an antitumor EV (bRSVF-EV) that carries misfolded proteins—typically considered cellular debris—and expresses the respiratory syncytial virus fusion protein (RSVF), enabling these vesicles to evade endosomal–lysosomal degradation. Treatment of RSVF-expressing HEK293T cells with bafilomycin A1 inhibited lysosomal function, thereby inducing the intracellular accumulation of misfolded proteins and facilitating their incorporation into EV. The resulting bRSVF-EV selectively transplanted xenogeneic antigens onto cancer cell membranes through a nucleolin-dependent mechanism, eliciting potent innate immune activation. Moreover, by escaping the endo–lysosomal pathway, these EV directly delivered misfolded proteins into the cancer cell cytosol, triggering endoplasmic reticulum stress and inducing immunogenic cell death (ICD). This mechanism produced strong antitumor immune responses in murine tumor models, and combination therapy with PD-1 blockade further extended survival, with some mice achieving complete remission. In summary, this dissertation provides a literature-based evaluation of EV-mediated endosomal–lysosomal escape strategies and demonstrates the therapeutic potential of a tumor-targeted oncolytic EV platform that induces ICD by delivering misfolded proteins directly into the cancer cell cytosol. 세포 간 상호작용은 기존에 알려진 직접적인 세포 접촉이나 사이토카인과 같은 분비 신호뿐 아니라, 최근에는 세포 외 소포체(extracellular vesicles, EV)와 같은 나노 크기의 소포를 통해서도 이루어지는 것으로 알려져 있다. EV는 세포막에서 유래한 막단백질, 세포질 내 단백질, 그리고 다양한 핵산을 함유하고 있어 생리적·병리적 정보 전달에 중요한 역할을 한다. 본 연구에서는 세포 외 소포체 엔지니어링을 통해 이러한 내부 담지 물질(cargo)의 전달 효율을 향상시키는 전략과, 바이러스 유래 융합 단백질을 활용한 전달 효과 증진 방안을 탐구하였다. EV를 치료제 전달체로 활용하려는 시도는 꾸준히 이루어져 왔으며, 최근에는 유전공학 기술의 발달로 mRNA, 전사인자와 같은 기능성 유전물질을 EV에 능동적으로 탑재하는 다양한 전략이 개발되었다. 그러나 이러한 물질들이 수용 세포로 내재화된 이후 엔도좀에 포획되고 리소좀 분해 경로를 거치며 상당량이 소실되는 문제가 제기되었다. 이에 따라 EV가 엔도-리소좀 분해 경로를 회피(endosomal–lysosomal degradation escape)하도록 유도하는 전략의 필요성이 대두되었고, 이를 위해 VSV-G와 같은 바이러스 유래 융합 단백질을 EV 표면에 발현시키려는 접근이 시도되었다. 본 연구에서는 지금까지 개발된 다양한 엔도-리소좀 분해 회피 기술과 그 효과를 정량적으로 평가할 수 있는 분석 방법들을 검토하고, 이러한 전략들이 EV 기반 치료제 개발에 어떻게 활용될 수 있는지 논의하였다. 본 연구에서는 일반적으로 세포 찌꺼기로 간주되는 비접힘 단백질을 효과적으로 탑재하고 엔도–리소좀 분해 경로를 회피할 수 있도록, 호흡기세포융합바이러스 융합단백질(RSVF)을 발현하는 항종양성 EV(bRSVF-EV)를 설계하였다. RSVF를 발현하는 세포주에 bafilomycin A1를 처리하여 리소좀 기능을 억제함으로써 비접힘 단백질의 세포 내 축적을 유도하였고, 이를 통해 EV 내부로의 효율적인 적재가 가능해졌다. 제작된 bRSVF-EV는 nucleolin 의존적 기전을 통해 암세포막에 이종(xenogeneic) 항원을 선택적으로 표면 이식하여 강력한 선천면역 반응을 유도할 뿐 아니라, 엔도–리소좀 분해를 회피하고 비접힘 단백질을 암세포의 세포질로 직접 전달함으로써 소포체 스트레스와 면역원성 세포사멸(immunogenic cell death, ICD)을 촉발하였다. 이러한 작용기전에 의해 마우스 종양 모델에서 뚜렷한 항종양 면역 반응이 유도되었으며, 특히 PD-1 억제제와 병용 투여 시 생존 기간이 현저히 연장되고 일부 개체에서는 완전 관해에 도달하는 우수한 치료 효과가 관찰되었다. 종합하면, 본 연구는 EV 기반 전달체에서의 엔도–리소좀 회피 전략에 대한 문헌적 고찰과 더불어, 비접힘 단백질을 암세포 세포질로 직접 전달하여 ICD를 유도하는 종양 표적화 oncolytic EV 플랫폼의 치료적 가능성을 제시한다.

Interfacial Engineering of Silicon Anode using 3D Cross-Linked PVDF-OH binder with Modulus-Controlled Solid Polymer Electrolytes

Yeong Gwang Jo 고려대학교 KU-KIST융합대학원 2026 국내석사

Silicon anodes offer exceptional theoretical capacity but suffer from severe chemo-mechanical degradation caused by large volume fluctuations, unstable interfacial reconstruction, and loss of electrode integrity. Here, a chemically integrated binder/solid-polymer-electrolyte design is reported for separator-free Si-anode solid-state cells. Hydroxylated poly(vinylidene fluoride) (PVDF-OH) provides reversible hydrogen-bonding interactions with hydroxylated Si surfaces, while diazide-mediated crosslinking converts the binder phase into a three-dimensional covalent network. The resulting cross-linked PVDF-OH binder exhibits an elongation at break of 122.9% and an electrode peel strength of 21.5 N m⁻¹, enabling reinforced Si-particle cohesion and suppressed electrode delamination. A modulus-controlled PVDF-HFP-based solid polymer electrolyte is further introduced as an integrated electrolyte/separator membrane for separator-free operation. Despite its lower ionic conductivity than more plasticized electrolytes, the P1A2 electrolyte delivers the most stable cycling because it balances Li⁺ transport with mechanical confinement. The optimized cross-linked PVDF-OH/P1A2 system retains 1587 mAh g⁻¹ after 150 cycles with 77.76% capacity retention, outperforming control cells based on pristine PVDF, uncross-linked PVDF-OH, liquid electrolyte, or mechanically weakened SPEs. This work demonstrates that mechanically balanced polymer integration, rather than ionic conductivity maximization alone, is critical for durable high-capacity Si-anode solid-state batteries. 실리콘 음극은 매우 높은 이론 용량을 제공하지만, 큰 부피 변화, 불안정한 계면 재구성, 전극 구조의 붕괴로 인해 심각한 화학-기계적 열화를 겪는다. 본 연구에서는 separator-free 실리콘 음극 기반 전고체 셀을 위한 화학적으로 통합된 바인더/고체 고분자 전해질 설계를 제시한다. 수산화된 poly(vinylidene fluoride) (PVDF-OH)는 수산화된 실리콘 표면과 가역적인 수소 결합 상호작용을 제공하며, diazide 매개 가교 반응은 바인더 상을 3차원 공유결합 네트워크로 전환한다. 그 결과 형성된 가교 PVDF-OH 바인더는 122.9%의 파단 신율과 21.5 N m⁻¹의 전극 박리 강도를 나타냈으며, 이를 통해 실리콘 입자 간 응집력이 강화되고 전극 박리가 억제되었다. 또한 modulus가 조절된 PVDF-HFP 기반 고체 고분자 전해질을 separator-free 구동을 위한 통합 전해질/분리막으로 도입하였다. P1A2 전해질은 더 높은 가소제 함량을 가진 전해질보다 낮은 이온전도도를 보였음에도, Li⁺ 전달과 기계적 구속 효과의 균형을 이루었기 때문에 가장 안정적인 사이클 성능을 나타냈다. 최적화된 가교 PVDF-OH/P1A2 시스템은 150사이클 후 1587 mAh g⁻¹의 용량을 유지하였고, 77.76%의 용량 유지율을 달성하였다. 이는 pristine PVDF, 비가교 PVDF-OH, 액체 전해질, 또는 기계적으로 약화된 SPE 기반 대조군 셀보다 우수한 성능이다. 본 연구는 높은 이온전도도의 극대화만이 아니라, 기계적으로 균형 잡힌 고분자 통합 설계가 고용량 실리콘 음극 기반 전고체 배터리의 내구성 확보에 핵심적임을 보여준다.

Selective Detection of Opioids Using a Nanodisc-Integrated Terahertz Sensing Platform

Seongbin Lee 고려대학교 KU-KIST융합대학원 2026 국내석사

Multichannel nerve guidance conduit with stem cell recruitment ability for enhanced nerve regeneration

박도연 KU-KIST Graduate School of Converging Science and 2020 국내박사

수천 개의 신경섬유의 재생 방향을 조절하고 재생 환경을 조성하는 것은 말초신경손상과 척수신경손상에서의 재생능을 향상시키는 데에 있어 매우 중요하다. 현재까지 존재하고 있는 많은 치료법과 연구들은 아직 위와 같은 조건들 없이, 많은 문제점들을 가지고 있다. 현재까지 최우선 치료법으로 여겨지고 있는 자가/동종신경이식의 경우, 수급 부족의 문제뿐 아니라 수여자 조직과 공여자 조직 간의 크기 차이의 문제가 큰데, 후자의 경우 신경종이 생길 수 있다. 단일채널 신경도관의 경우는 물리적인 조절/유도 장치가 없어 잘못된 연결을 일으킬 수 있다. 또한, 단일채널 신경도관에 줄기세포 등의 세포를 배양하여 이식하는 경우 안전의 문제를 간과할 수 없다. 따라서, 이러한 모든 문제들을 모두 해결하는 새로운 도관의 개발을 위해 많은 연구가 진행되고 있다. 이를 위한 대표적인 제작방법은 thermal drawn 방법과 3D 프린팅 방법이 있다. Thermal drawn 방법은 가열된 상태에서 고분자를 압출시키는 방법이며, 3D 프린팅은 고분자를 원하는 위치에 쌓아올리는 방법이다. 하지만, 이러한 방법으로 제작된 신경도관도 여러 한계를 갖고 있고, 실제 자가/동종신경이식만큼의 재생효율을 보여주지 못하고 있다. 또한, 여러 생체적합한 물질들을 이용하여 신경재생의 효율을 증가시키려는 노력 또한 진행되고 있다. 하지만, 재료만 가지고 신경을 재생시키는 방법은 신경섬유의 재생방향을 조절하지 못한다는 명확한 한계를 가지고 있다. 이에 따라, 많은 연구자들은 더 나은 신경재생을 위해서는 제작방법의 진보와 재료연구의 복합적인 융합연구가 필요하다고 지적한다. 본 박사학위 논문에서는 마이크로칩 기술과 고분자 공학의 융합으로 발전된 신경재생능을 일으킬 수 있는 신경도관을 제작하였다. 마이크로칩 기술은 미세구조의 크기 및 수치까지 조절가능하며, 고분자공학은 기존 고분자의 성질을 변화시킬 수 있기에 이 논문에서는 이러한 장점들을 융합함으로써, 수치 조절이 가능한 미세채널을 수 백개 가지고 있으며 능동적으로 내부환경을 재생에 적합하게 바꿔주는 신경도관을 제작하였다. 그 개념을 간단히 아래와 같다. Poly(L-lactide-co-ε-caprolactone) (PLCL) 고분자를 클로로포름 용액에 녹인 고분자 용액을 요철의 반복되는 미세패턴을 가지고 있는 PDMS mold에 넓게 도포한 후, 그 채로 메탄올 배지에 넣어 PLCL이 패턴을 가진 채 석출되도록 하였다. 그런 후, 패턴을 가진 PLCL sheet를 미세패턴에 수직인 방향으로 굴려주면 PLCL sheet의 패턴이 새겨진 부분과 패턴이 새겨지지 않은 부분이 만나면서 패턴의 들어간 부분 개수만큼의 미세채널이 형성된다. 여기서, PLCL-SP (substance P(SP)가 공유결합된 PLCL)을 일정비율로 섞어서 사용한다면, 줄기세포 유도능이 있는 SP로 인해 수백 개의 미세 채널로 수여자의 줄기세포가 모여들어 재생을 도울 수 있을 것이다. 완전한 형태의 미세채널을 갖는 신경도관의 제작을 위해서 미세패턴의 디자인이나 PLCL 고분자 용액의 농도 등의 요소들이 최적화되었다. 말초신경손상 모델에 본 신경도관이 이식되어 미세채널에 의해 신경재생의 방향을 조절하는 것과 SP에 의해 줄기세포 유도능을 갖는 것이 확인되었으며, 이러한 특징들이 신경재생에 어떤 영향을 끼치는지에 대한 정량적인 분석이 진행되었다. 또한, 척수신경손상 모델에 대해서도 같은 측정이 진행되어 본 신경도관이 척수신경손상 모델에 사용될 수 있는 가능성을 제시했다. 마지막으로, 위의 신경도관 모델이 재생을 위한 다른 많은 방향에서도 사용될 수 있음을 보이기 위해 전반적인 모양을 변형시켜 분지된 형태의 신경도관을 만들거나 수백 개의 미세채널 내에 지형적 신호 (topographic cue)를 새겨넣는 것을 보였다. 즉, 이 논문에서 제시한 신경도관 제작방법, 즉 마이크로칩 기술과 고분자 공학의 융합을 기반으로 한 제작방법은 앞으로 추가적인 발전가능성이 있어, 추후 말초신경 및 중추신경 손상에 대한 새로운 치료법으로 발전할 수 있다고 할 수 있다. Guiding the regrowth of thousands of nerve fiber within a regeneration-friendly environment enhances the regeneration capacity in peripheral nerve injury (PNI) and spinal cord injury (SCI). Although there exist current clinical treatments and various researches, all have their critical limitations that no seamless results have been found. Autograft/allograft, regarded as gold standard so far, has not only a scarcity problem but also the size difference problem, which could induce neuroma formation. Single-channel nerve guidance conduit (NGC) increases the induction of erroneous re-innervation due to the absence of the alignment cue in it. Also, single-channel NGC seeded with cells, especially stem cells, has a safety issue. Accordingly, various trials to develop NGC desirable for nerve regeneration have preceded. Representative fabrication approaches for NGC include a thermal drawn method and 3D printing. Thermal drawn method employs the heated extrusion for the production of polymer-based NGC, and 3D printing is stacking the polymer at the desirable site to build NGC with pre-defined design. However, NGCs fabricated by each method differ from the native nerve tissue very much and often followed poorer results than the autograft/allograft did when implanted. Also, various biocompatible materials have been developed to enhance nerve regeneration. However, the material-only approach has a definite limitation that the direction of nerve regrowth is hardly controlled. Therefore, combinatorial approaches are needed to fabricate desirable and nerve-tissue like NGC. In this paper, NGC with improved capability for nerve regeneration was produced by the convergence of microchip technique and polymer engineering. Since microchip technique has the advantage of controlling each dimension of the microstructure, and polymer engineering has the advantage of modifying the characterization of the polymer, NGCs produced in this work have a controllable size of length, diameter, and the microchannels, and can actively form the regeneration-friendly environment within the microchannels. Poly(L-lactide-co-ε-caprolactone) (PLCL) dissolved in chloroform was bathed in a methanol solution to result in precipitation of PLCL onto a polydimethylsiloxane (PDMS) mold (width*length = 12 mm * 40 mm) engraved with repeated ridges and grooves. Rolling the precipitated PLCL substrate, on which micropatterns of ridges and grooves were engraved, makes the patterned part of the substrate meet the planar part of the substrate, forming multiple microchannels. Here, PLCL-SP, PLCL immobilized with substance P (SP) that is a well-known stem cell recruitment factor, was employed to achieve a NGC with hundreds of microchannels having stem cell recruitment ability. Various factors including micropattern design and PLCL concentrations were explored for the optimized form of multichannel NGC. Neuronal alignment and regeneration along these microchannels and the action of SP for enhanced regeneration after PNI were verified, followed by measuring quantitative parameter for directing the enhanced nerve regeneration capacity of NGC fabricated in this study. Next, the same measurement was conducted for the implantation to the SCI model. This suggested the possibility of this NGC be used as SCI treatment. Finally, to assess the ability to use the proposed NGCs in diverse applications, we suggested a modified and augmented form of NGC by showing bifurcated morphology of mNGC or adding directional topographies on the microchannels. Additional improvements in the fabrication process will advance the development of regeneration research and treatment for peripheral/central nerve injury.

Surface modification of two-dimensional transition metal carbide (MXene) for non-polar organic dispersions

김대신 KU-KIST Graduate School of Converging Science and 2019 국내석사

Herein, we describe a simple way to prepare a stable Ti3C2Tx MXene dispersion in a non-polar organic solvents via the simultaneous surface modification and phase transfer. The hydroxyl terminal groups of the Ti3C2Tx nanoflakes are physically adsorbed with amine ligands and chemically modified with alkylphosphonic acid ligands to form a stable covalent Ti-O-P bond through interfacial condensation reaction at the liquid-liquid interface and the surface-modified Ti3C2Tx nanoflakes deliver from aqueous to organic phase simultaneously. Unlike conventional surface modification method, it is a simple and easy one-step process for fabricating Ti3C2Tx organic dispersion in various organic media from high polar isopropyl alcohol to non-polar chloroform and toluene. The non-polar Ti3C2Tx dispersion in chloroform reveals strong oxidation stability and promotes long-term storage, and also provides new opportunities to prepare MXene nanocomposites with non-polar organic soluble polymeric matrix for many future applications. 2차원 나노입자인 맥신 (MXene)은 우수한 수 분산 특성 및 다른 2차원 물질보다도 우수한 전기전도도를 가지고 있어 에너지 저장 소재 분야 및 전자파 차폐 소재로 널리 응용되고 있다. 또한 표면 말단작용기를 이용한 촉매 및 센서 분야의 연구도 활발히 진행되고 있다. 하지만, 수 분산 맥신은 물 분자 및 용존 산소에 의해 쉽게 산화되어 금속산화물로 변하게 되며, 친수성 표면을 가지는 맥신은 가공 이후 수분이 제거된 상태에서도 대기 중의 수분에 의해서도 쉽게 산화되어 그 본래의 우수한 특성을 잃게 된다. 또한 친수성 표면을 가지는 맥신은 소수성을 가지는 이종의 재료(고분자 등)와의 인력이 낮아 균일한 복합체, 하이브리드 재료를 형성하는데 제한이 있다. 본 연구는 맥신 표면을 소수성을 가지거나 기능기를 가지는 리간드 (amine ligand 및 alkylphosphonic acid)를 liquid-liquid phase transfer 방법으로 개질하여, 맥신 표면에 소수성 특성을 부여하였고, 개질된 맥신의 유기용매에 대한 분산성을 향상시켰다. 유기용매에 분산된 맥신은 기존 수 분산 맥신 보다도 우수한 산화 안정성을 가졌으며, 소수성 고분자와의 복합체 용액을 스프레이 코팅과 같은 액상 공정을 적용함으로써 복합체 필름을 제조하여 그 특성을 파악하였다.

Anticancer activity evaluation and action mechanism studies of novel BRAF inhibitors

최승혜 KU-KIST Graduate School of Converging Science and 2020 국내박사

Kinomics is a study of kinase, phosphatase and related molecular targets. To date, an estimated 518 protein kinase genes have been identified in the human. Maintaining the cellular homeostasis, specialized cellular function according to cell type and the reaction by extracellular stimuli are all mediated by intracellular proteins. A major mechanism of protein regulation is to utilize protein kinases. Kinase plays a very important role in metabolism, cell signaling, protein regulation, cell transport, secretion, and numerous other cellular response pathways. In addition, proteins, lipids, or carbohydrates present in vivo change their capabilities to bind to other molecules, depending on their phosphorylation status. Therefore, to understand molecular mechanisms of kinases is very important because it is linked to phathogenesis, disease development and the establishment of new therapeutic strategies. Targeted anticancer drug selectively kills cancer cells by blocking signals that are involved in the growth and development of cancer as targets for specific proteins or specific genetic changes that appear only in cancer cells. Most cancers are caused by the accumulation of multiple oncogene mutations, unlike the pathogenesis of CML caused by bcr-abl translocation. Therefore, in the case of a specific or selective low-molecular compound that inhibits only one mutation, there is an advantage of low side effects, but low therapeutic performance. Therefore, there is a growing trend in the interest in the combined use of approved drugs. Combination therapy can be expected to have a higher therapeutic performance than when a single drug is administered, and in particular, may be a method of overcoming new drug resistance caused by drug administration. Chapter 1 is a general introduction to kinomics and kinase, chapter 2 is a study of novel multi-targeted kinase inhibitors that can treat ATC (anaplastic thyroid cancer) of which effective targeted therapeutic strategies are currently not available and chapter 3 is a study for novel BRAF inhibitors capable of inhibiting strongly class I/II/III BRAF mutants.

Three-dimensional angiogenic sprouting into type I collagen hydrogel modified by Maillard reaction

Choi BongHwan 고려대학교 KU-KIST융합대학원 2018 국내석사

Previous papers have described various types of hydrogel for three-dimensional in vitro culture models. Collagen gel modification using the Maillard reaction is included. Advanced glycation end products(AGEs) induced by the Maillard reaction form additional crosslinks within the collagen fibril. This may lead to structural changes in the collagen fiber, a bundle of fibril, but it has not been shown in detail. In addition, there have been few studies on changes in cell invasion due to changes in collagen gel microstructure. Here, we show the microstructure of the modified collagen gel by the Maillard reaction using ribose by scanning microscopy(SEM) and fluorescence imaging. Applying this modified collagen gel to a conventional microfluidic chip, we observed changes of cell sprouting depending on gel microstructure using human umbilical vein endothelial cells(hUVECs). As the concentration of ribose increased, the fiber thickness and the pore size increased rapidly. The length and diameter of lumen was enlarged depending on ribose concentration. With these results, collagen gel modified by the Maillard reaction is more beneficial for making 3D in vitro micro vessel models.

(A) study on vibration-based piezoelectric and electromagnetic hybrid energy harvesting for efficient energy conversion

정인기 KU-KIST Graduate School of Converging Science and 2019 국내박사

With the advent of the IoT era, the demand for sensors has increased significantly. A notable fact is that these sensor systems can communicate with each other over wireless networks in the IoT era. Especially, in particular sites where access to power is difficult, batteries have been installed as a power source. However, these batteries have a limited lifetime and require periodic replacement. Thus, various energy harvesting technologies have received research attention to realize an autonomous wireless sensor network. In this study, we designed and demonstrated a piezoelectric/electromagnetic hybrid energy harvester that can generate a significant amount of electricity at vibration environments. Oval-like configuration using two curved PEG based on MFC (Macro-fiber composite) induces large displacement of a magnet installed at the top surface. As for the electromagnetic energy harvesting, there are three solenoid coils with series-connection above the magnets. Especially, the hybrid energy harvester contains two magnets facing the same polarity on both sides of Oval-shaped structure to enhance displacement due to its spring-like behavior. In order to compare actual output power with theoretical output power, we studied the relationship between damping parameters and power output generated from the energy harvester. Here, the mechanical and electrical damping ratios were extracted by measuring both induced displacement and generated power output of the Oval-shaped hybrid energy harvester. The Oval-shaped hybrid harvester was tested in a vibration environment, where the input vibration is assumed to be the harmonic excitation and it has 60 Hz frequency and 0.5 G acceleration amplitude. The hybrid output power of Oval-shaped hybrid energy harvester with magnetic spring is 25.45 mW which is approximately 1.14 times higher than that of the PEG alone and 2.16 times higher than that of the EMG alone. Also, we successfully operate a wireless IoT sensor module by utilizing the developed hybrid energy harvester with a power management circuit under vibration environment. As a result, the milliwatt-scale energy harvesting is achieved, providing the opportunity to realize an autonomous sensor system to come in the future.

(A) comparative study on the sensitivity and multiplexing capability with magnetic microparticles for bacterial target DNA detection

황민지 KU-KIST Graduate School of Converging Science and 2020 국내석사

In order to prevent sepsis, it is important to identify bacteria at an early symptom stage. Blood culture, the most common method to identify bacteria, take at least 24 hours and up to 5 days. Here we suggest a comparative study of fluorescence and surface enhanced Raman scattering (SERS) on the sensitivity and multiplexing capability with magnetic microparticles (MMPs) for bacterial target DNA. In this work, the method can simultaneously identify bacteria that cause sepsis, such as Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus. And by using magnetic microparticles, it is possible to detect rapidly than conventional methods, and the solution is concentrated to amplify the signal. Subsequently, it is proved that it has high sensitivity and multiplexing capability by fluorescence and surface-enhanced Raman scattering. The SERS method had a sensitivity of approximately 10 fM, which is 10,000 times more sensitive than the fluorescence method. In addition, both fluorescence and SERS enables the diagnosis of multiple bacteria genomic DNA. Further development of this assay has promising potential as a rapid point-of-care system for early infection management in clinic.

Study on the lithium-alloys based electrochemical transducers : non-volatile actuators and energy harvesters

노명섭 KU-KIST Graduate School of Converging Science and 2019 국내박사

The electrochemical alloy materials such as LixSi and LixGe are characteristic of the stress-composition coupling. Changes in the lithium composition cause stress in the electrochemical alloy materials. On the other hand, applying stress to the material means that the lithium composition is changed. In this thesis, I have implemented two devices with unique characteristics using the above mentioned phenomenon. Conventional actuators used in the artificial muscle induce bending by aligning large-sized ions upon bias application. Such design, alike many other actuator types, suffer from volatile actuation where the actuated position gets lost upon switch-off. we develop a non-volatile artificial muscle with ion insertion electrode materials. Upon bias application, the inserted ions pose stress on the electrodes that sustain even after power shut-off. The demonstrated actuator consists of LixGe thin films deposited on both sides of a flexible polyimide substrate. The device exhibits 35.2mm displacement when operated at 2 V and generates the blocking force of 0.67 mN. The observed stress and volume expansion reach 248 MPa and 8.2% for the 284 nm Li3Ge thin films, respectively. The actuated position is maintained against gravity with 12.1% decay in the actuated distance after 10 minutes. The novel actuator type proves the potential use of lithium insertion materials as actuation materials and shows that non-volatile actuation can be realized with ion-insertion electrodes. Also, I have developed new type of a hydrostatic pressure driven electrochemical energy harvester. The potential difference occurs due to the difference in stress applied to LixSi nanoparticles (NPs) and LixSi@TiO2 yolk-shell (YS), when applied pressure. The lithium ions migrate from the NPs subjected to compression to the opposite YS. At the same time, the charge moves through the external circuit. The energy harvester generates current peak shape with very long duration time like a direct current (DC) compared to the existing energy harvesters such as piezoelectric, triboelectric and electromagnetic. This characteristic can be efficiently driven in a lower frequency band. Also, internal resistance is very low about 50 Ω. This characteristic can be suitable for various electronic devices, considering that the internal resistance of the electronic devices is usually designed to be low.