3D Printing of surface-area-controlled polymeric structures for removal of arsenic

김기훈 서강대학교 대학원 2018 국내석사

Preparation and characterization of gel polymer electrolyte-based lithium ion battery using a radiation technique

최지훈 서강대학교 대학원 2020 국내석사

In this research, the in situ formation of poly(vinylpyrrolidone based gel polymer electrolyte (PVP-GPE) inside LIB cell was studied by quicker and more efficient electron beam irradiation. For this purpose, a radiation sensitive GPE precursor solution was prepared by mixing VP as a monomer, PD as a crosslinker with a commercial liquid electrolyte, and gel behavior and electrochemical characterization were performed at various irradiation doses. The analytical results revealed that PVP-GPE was created by EB irradiation at the absorbed dose of 1 kGy (corresponding to th e irradiation duration of 3 seconds). The PVP-GPE-1 exhibited a gel fraction of 97%, good thermal stability, good electrochemical stable voltage window (2.0 ~ 4.7 V), and good ion conductivity. As a result, the in situ formation of PVP-GPE-1-based coin-type LIB cell showed the initial discharge capacity of 133 mAh/g, and its capacity retention at the cycle number of 50 was 69%, quite comparable to that with a liquid electrolyte (135 mAh/g and 72%). 본 연구에서는 상온 방사선가교반응을 이용하여 조립된 전지의 액상전해질을 겔 전환시켜 이차전지를 제조하고 전지의 성능평가를 수행하고자 하였다. 일정 조성비에서 1-Vinyl-2-Pyrrolidone (VP), Poly(ethylene glycol) diacrylate (PD), 1 M LiClO4 liquid electrolyte를 이용하여 방사선 민감성 전구체 조성물 를 제조하고 다양한 방사선 조사 조건하에 겔 거동 및 전기 화학적 특성 분석을 수행하였다. 형성된 겔 전해질의 특성 분석 결과 92 wt% 액상 전해질 을 함유한 겔 전해질 이 성공적으로 제조 되었고 액상전해질과 유사한 수준의 이온 전도도와 4.7 V 까지 전기화학적으로 분해되지 않고 안정함을 확인하였다. 최종적으로 겔 전해질 기반 코인셀 단위전지 적용 성능 평가 결과 방전용량은 상용 액상전해질 기반 단위전지에서 보고되고 있는 수준과 유사한 수준 으로 유지됨을 확인하였다.

Fabrication of thermoelectric temperature sensors for paper-based microfluidic chip

채희도 서강대학교 2017 국내석사

최근에 랩온어칩(lab-on-a-chip, LOC)을 구현하기 위한 방법으로 종이에 미세유체칩을 제조하는 연구가 많이 진행되고 있다. 이러한 방식은 환경 친화적이고 간단하며 경제적인 방법이라는 점에서 큰 장점을 지닌다. 그러나 금 나노 입자의 합성, 단백질 결정화 및 중합효소 연쇄 반응(PCR)과 같은 화학 반응에서 시료를 가열하고 온도를 정확하게 제어하는 것이 점점 더 요구되고 있다. 기존의 미세유체칩 연구의 대부분은 외부 히터 및 온도 센서를 사용하여 이러한 과정들을 진행하였기에 시스템의 간소화에 어려움이 컸다. 특히 LOC를 이용하여 POC(point of care) 장치를 구현하는 것에는 더욱 어려움이 있다. 따라서 본 연구에서는 온도 제어가 가능한 미세유체칩을 만들기 위해 종이에 히터 및 온도 센서의 인쇄 제조가 연구되었다. 이를 위해 적절하게 제조된 PEDOT:PSS, MWCNTs 잉크의 제조를 연구하였고 이것을 스크린 프린팅 및 스프레이 프린팅과 같은 방식을 통하여 미세유체칩을 만드는 방법에 대해 연구하였다. 이 두 물질의 제벡계수는 은 나노 입자 (AgNP)로 구성된 금속 기반 전극을 상대 전극으로 이용하여 측정되었다. 제벡계수는 스크린 인쇄 된 PEDOT : PSS 및 MWCNTs에 대하여 각각 19.86μV/K 및 2.66μV/K였다. 재료의 특성을 분석한 후 미세유체칩과 센서가 같이 인쇄 제작되었다. PEDOT:PSS와 MWCNTs로 만든 온도센서와 히터는 가깝게 배치되어 시료가 오가면서 온도를 측정할 수 있도록 설계되었으며 시료가 전기습윤방식을 이용하여 미세유체칩의 길을 따라 이동할 수 있게 설계되었다. 온도 센서와 히터는 Labview 컨트롤러 프로그램에 의해 자동 제어되고 미리 측정된 기울기 및 절편을 이용하면 온도를 계산하여 나타낼 수 있다. AgNP와 인쇄된 PEDOT : PSS의 열전 패턴은 11.90 μV/K의 기울기를 보였으며, 절편은 -44 μV였다. MWCNTs로 인쇄된 패턴은 7.06μV/K, 절편은 -100μV였다. 센서의 성능은 실온과 100 ℃ 사이의 범위에서 ± 2 ℃의 오차로 일반적인 온도 변화를 감지하기에 충분하다고 할 수 있다.

Fabrication of paper-based chemical reactor with dispensing system for synthesis of au nanoparticles and formulation of conductive inks

백승휘 서강대학교 대학원 2016 국내석사

절연체 막으로 코팅한 도체 표면 위에서 액체 방울의 운동을 전위차로 제어하는 전기습윤(electrowetting on dielectrics, EWOD) 구동용 종이기반 마이크로 유체칩(paper-based microfluidic chip)을, 전도성 잉크와 잉크젯 인쇄 기술을 사용하여 제작하였다. 본 연구에서는 기존에 쓰이던 탄소나노튜브(CNT) 잉크에 은 나노입자(AgNPs)를 혼합하여 제조한 CNT/AgNPs 복합체 잉크를 사용하였다. 새로운 CNT/AgNPs 잉크는 기존의 CNT 잉크 보다 동일한 인쇄 횟수 기준으로 약 1000 배 가량 전도도가 높기 때문에 인쇄 해상도를 높일 수 있을 뿐만 아니라, 전기에너지의 소모를 줄이고 EWOD현상으로 유도되는 액체/고체의 계면 사이의 표면장력을 줄여주기 때문에 액체의 구동력을 더욱 증가시킬 수 있다. 개방형(open) 방식의 마이크로 유체칩에서는 액체의 이동(transport), 병합(merging)을 쉽게 구현할 수 있지만, 분리(separation), 방울의 생성 (creation) 및 분배(dispensing)의 경우 개방형 방식의 마이크로 유체칩에서는 특수한 경우를 제외하고는 거의 불가능하다. 따라서 폐쇄형(closed) 방식의 마이크로 유체칩 방식의 디지털 종이 마이크로 유체칩 개발이 절실히 요구되고 있다. 본 연구에서는, 범용 acetate 필름을 사용하여 복잡한 광리소그래픽 공정을 요구하는 고가의 유기고분자를 대체하는, 커터기(cutting plotter)를 사용하여 저비용, 신속 및 고성능 dispenser를 개발하였다. 이 dispensor가 장착된 폐쇄형 마이크로 종이 유체칩은 액체의 분리를 정량적으로 제어할 수 있기 때문에, 종이 위에서 물방울을 디지털 단위로 제어하여 미세하고 정밀한 화학 반응을 가능케 해준다. 본 연구에서는 금 나노입자를 합성하는 응용연구를 수행하였다.

Fabrication of inkjet-printed heaters and application for microfluidic polymerase chain reaction chips

Ly, Mai Nguyet 서강대학교 대학원 2021 국내석사

Inkjet printing deposits the resistive materials to form a patterned heater easily, quickly, and economically in high resolution on paper and flexible substrates, which can convert electric energy to thermal energy when current is applied, based on Joule heating effect. Up to our knowledge, inkjet-printed heater has recently been introduced for nucleic acid amplification test but limited to isothermal amplification with a single heating zone to provide only one constant temperature. Aiming to extend its usage for the conventional polymerase chain reaction (PCR) that requires different temperatures, here we present the fabrication of polyimide film heaters using Dimatix inkjet printer with aqueous conductive silver nanoparticle ink. For that, firstly we optimized the ink, design and printer setting to attain high consistency of heater quality. After thermal annealing at 250 oC, we characterized the material, electrical, and thermal properties of the printed heaters. To maintain durability when a high electrical load of current was applied, it was important to keep the number of printing layers at three. A typical U-shape heater, of which the average end-to-end resistance was at 28.166 +/- 0.893 Ohm in case of 0.40 mm / 0.40 mm stroke weight ratio of heating regions, had been investigated. For PCR application, we proposed a four-heating-zone system with two interdigitated U-shape heaters whose stroke weight ratios were 0.45 mm / 0.35 mm, and 0.45 mm / 0.25 mm, after optimization. Target temperatures were obtained after 15 min when using with a temperature controller. This four-heating-zone system could maximize the number of thermal cycles on a limited area of PCR chip when we combined with corresponding flow channel design. By using xurography, we had prototyped a continuous flow microfluidic device with polydimethylsiloxane (PDMS) 5:1 for testing efficiency of our four-heating-zone system and set up a platform to measure, control, and analyze the result of PCR amplification.

Design of Liposome-Based Nucleus Mimic System for DNA Amplification, Pore Formation and Controlled Release of Genetic Materials

허은진 서강대학교 일반대학원 2023 국내석사

The study of artificial cells plays an important role in understanding the functions and processes of cells. By studying artificial cells, researchers can create simplified model systems that mimic cellular components and processes to gain insight into key mechanisms and the origin of life. The nucleus is essential for overall cellular function and reproduction, which involves DNA replication and the release of genetic material to the external environment, so in this study tried to mimic the replication and release of genetic material. Advances in research have made it possible to replicate and release genetic material within artificial cells using techniques such as polymerase chain reaction (PCR) and creation of pores using pore forming materials have been studied to control the release of internal materials from artificial cells. In this study, we aim to replicate the DNA through PCR and create pores using azo lipids to mimic gene activity to perform complex mechanisms within artificial cells. We expect that this study will lead to advances in cell mimicry research and on understanding of the origin of life.

3D printing of surface-area-controlled polymeric structures for removal of arsenic

김기훈 서강대학교 2018 국내석사

During the last decades, arsenic poisoning has been recognized as a worldwide problem. The threat of arsenic contamination to public health in developing countries is far more serious due to their high dependence on natural water sources. Many technologies for arsenic removal have been investigated and developed. However, because of the absence in rural areas of an infrastructure for large-scale water treatment, the filtering process, if it is to be successful, should be low-cost, small-scale, easily customized, and capable of being operated without electrical power. In this thesis, we introduce the first water filtration system for arsenic removal which was fabricated by three-dimensional (3D) printing technique. 3D printing itself can provide a compact and customized filtration system that meets the above-mentioned requirements and is made with abundant plastic materials. Moreover, due to the versatility of 3D printing, the internal surface area of the filters can be controlled to increase arsenic adsorption during filtering under atmospheric conditions. We investigated the effect of a controlled surface area on the flow rate and the deposition of the adsorbent, which are directly related to the adsorption of arsenite ions. To describe the arsenic adsorption on our 3D printed filtration system, we conducted batch, isotherm and column studies. We expect that this novel approach can be applicable to take advantage of architecture differences for various fields.

Artificial cytoskeleton in vesicle : polymerization of actins and microtubules in a single vesicle for mimicking cellular motility

정성우 서강대학교 대학원 2020 국내석사

In biochemistry research, creating and fully understanding cellular structures and activities has always been one of the primary research interests. Investigations related to the mechanisms underlying the actions of various structural components and associated machinery widely use artificial cellular models. In particular, the physical cellular membrane-cytoskeleton interactions are essential in defining the morphology and its motility of living organisms. We developed the cell mimics, enclosed with one of the cytoskeleton proteins (F-actins). These systems to quantify the forces involved in actin polymerization and to resolve spatially the forces exerted in different membrane regions. These filaments successfully assembled into micron-sized, rigid bundles that adhered to and deformed the surface of the vesicle, consequently inducing the morphological change of the artificial cell via membrane-cytoskeleton interaction. Here, we built several differently conditioned giant unilamellar vesicles (GUVs) to control the actin-membrane interactions. Depending on the phases of the GUVs, ordered/disordered phases from saturated/unsaturated lipids, the GUVs exhibited a range of attraction-repulsion interactions with actin filaments. As we triggered the actin polymerization, the GUVs showed three different morphologies: phase-separated, Lo phase deprived, mixed-phase. Each GUVs morphologies showed different actin-membrane interactions: strong interaction, inner crust, no interaction. Through manipulating the actin-membrane interaction by lipid phase-separation, we could succeed in implementing artificial cells with morphological dynamics toward cellular motilities.

Temperature controller on paper-based digital microfluidics for DNA amplification

김윤표 서강대학교 대학원 2019 국내석사

최근에 다양한 기능성 나노재료 잉크를 인쇄하는 종이 전자 기술이 급속히 개발되고 있다. 그중에서, 유연한 종이 기판 위에 인쇄된 전극 위에서 디지털화된 유체의 단위인 액적을 이용하는 디지털 미세유체칩(digital microfluidic chip, DMF)이 크게 주목받고 있으며, 이 기술은 전기습윤 기술을 통해 액적의 수송, 분리, 분배 및 혼합을 정밀히 제어하여 원하는 화학반응을 자동화하여 수행할 수 있다. 기존의 개발된 p-DMF 종이칩에는 온도조절 장치가 없어서 흡열반응을 처리할 수 없는 제약이 있었다. 본 연구에서는, 잉크젯 프린터로 인쇄한 온도 센서와 전기 히터로 온도 조절장치를 제조하였고, 정밀한 온도 제어가 필요한 DNA 증폭에 응용하였다. 줄열(Joule heating)을 이용한 히터와, 열전 현상(thermoelectric effect)을 이용한 열전대형 온도 센서를 이용하였으며, 이를 위해 은 나노입자와 PEDOT:PSS 고분자 재료 잉크를 사용하였다. 가장 주목할 장점은 이러한 전극들을 액적을 움직임을 제어하는 전기습윤의 구동 전극으로도 사용될 수 있다는 점이다. 온도 센서의 PEDOT:PSS와 은 나노입자의 접합 계면으로부터 측정된 제벡 계수(Seebeck coefficient)는 18.873 μV/K로 측정되었다. 각각의 구성요소를 통합하기 위해, 랩뷰 소프트웨어를 기반으로 한 PID 제어가 사용됐다. 또한, 물방울의 증발과 열 손실을 최소화하기 위해서, 광물 유가 채워진 완전히 밀봉된 칩을 이용했다. Recently, paper-based electronic technology printed with various functional nanomaterial inks has been rapidly developed. Among them, a digital microfluidic chip (DMF) using a droplet as a unit of a digitized fluid on an electrode printed on a flexible paper substrate has attracted much attention, and the desired chemical reaction can be carried out automatically by precisely manipulating transportation, split, dispensation and mixing of droplets using electrowetting. The previous paper-based p-DMF chip did not have a temperature controller, thus there was a limitation that the endothermic reactions could not be conducted. In this study, we fabricated a temperature controller composed of micro heater and temperature sensor printed with an inkjet printer, and this temperature controller was applied to DNA amplification that requires precise temperature control. We employed Joule heating and thermoelectric effect for micro heater and temperature sensor, and PEDOT:PSS polymer and silver nanoparticle inks were utilized. The main advantage of these functional electrodes is that they can also be used as driving electrodes for electrowetting. Seebeck coefficient of a temperature sensor was 18.873 μV/K obtained from an interfacial junction of PEDT:PSS and silver nanoparticle. PID controller based on Labview software was utilized to incorporate each component together. Also, we used a fully enclosed-chip filled with mineral oil to minimize evaporation and thermal loss of a droplet.

Micro-dispensers on inkjet-printed, paper-based digital microfluidic device for gold nanorod synthesis reactions

정해나 서강대학교 대학원 2018 국내석사

Digital microfluidics (DMF) has become an important tool that is useful for a wide range of liquid handling applications. Especially Paper DMFs has emerged as a simple and low-cost method to fabricate fluid manipulation devices. This paper presents an Inkjet-printed, paper-based digital microfluidic device with an accurate micro-dispenser developed for unequal droplet splitting. In this research, we developed a micro-dispenser using unequal droplet splitting, unlike most of the previous researches that were based on equal splitting. To characterize the micro-dispenser, the effects of the applied voltage and the sub-electrode geometry on the splitting performance are studied. The droplet size increased showing a linear behavior in the range of the applied voltage 180-340 Vpp while the frequency was 1.0 kHz. For the effects of the sub-electrode geometry the height and width factors were concerned. This part of the study illustrates that there is a linear relation between the area of the split droplets and the area of the sub-electrodes. This linear behavior allows for the selection of an appropriate size of the sub-electrodes to be actuated based on the desired volume of the droplet We performed a seed meditated gold nanorod synthesis on this inkjet-printed, paper-based device, which was possible to make different sizes of gold nanorods with aspect ratio 2.3, 18.9, 33.0 by controlling the volume of growth reagent amounts. We propose that this represents a breakthrough for DMF, possibility for high precision reactions on-chip by the Micro-dispensers. This simple, low-cost, precise device will be an attractive alternative to various chemical reactions at resource limited and educational fields.