Scale-Up of Monodisperse Emulsion/Bubble Generation using microfluidic device

정헌호 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Emulsion and gas bubble has led to significant progress in multiple area including materials synthesis, ultrasound imaging, and droplet-based high-throughput biological assay. One important challenge that may determine the commercial success and translation of microfluidic technologies is the mass production of monodisperse droplets and bubbles. In this work, we have developed a three-dimensional monolithic elastomer device (3D MED) to enhance the production rate of liquid droplets and gas bubbles. Based on double-sided imprinting technique, 3D microchannels architecture are formed in a monolayer elastomer that has one thousand parallel droplet/bubble generators. Because of the robustness of the microfluidic device, 3D MED could potentially be used for wide applications that require highly monodisperse droplets and bubbles.

Microfluidic approach for mass production of monodisperse droplets

정헌호 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Emulsion and gas bubble has led to significant progress in varying area including materials synthesis, ultrasound imaging reagents, and biological high-throughput screening. One important challenge that may determine the commercial success and translation of microfluidic technologies is the mass production of monodisperse single and core-shell droplets/bubbles. In this work, we have developed a three-dimensional monolithic elastomer device (3D MED) to achieve the mass production of monodisperse single and core-shell droplets/bubbles. Based on double-sided imprinting technique, three dimensional microchannels architecture are formed in a single-sheet elastomer that has parallel droplet/bubble generators. Because of the scalable and robustness of the microfluidic device, 3D MED could potentially be used for wide applications that require highly monodisperse droplets and bubbles in the industry and research fields.

미세유체장치를 이용한 생분해성 Polycarprolactone의단분산성 미세입자 생성제어

정헌호 한국청정기술학회 2019 청정기술 Vol.25 No.4

Monodisperse microparticles has been particularly enabling for various applications in the encapsulation anddelivery of pharmaceutical agents. The microfluidic devices are attractive candidates to produce highly uniform droplets thatserve as templates to form monodisperse microparticles. The microfluidic devices that have micro-scale channel allow precisecontrol of the balance between surface tension and viscous forces in two-phase flows. One of its essential abilities is togenerate highly monodisperse droplets. In this paper, a microfluidic approach for preparing monodisperse polycaprolactone(PCL) microparticles is presented. The microfluidic devices that have a flow-focusing generator are manufactured bysoft-lithography using polydimethylsiloxane (PDMS). The crucial factors in the droplet generation are the controllability ofsize and monodispersity of the microdroplets. For this, the volumetric flow rates of the dispersed phase of oil solution and thecontinuous phase of water to generate monodisperse droplets are optimized. As a result, the optimal flow condition for dropletdripping region that is able to generate uniform droplet is found. Furthermore, the droplets containing PCL polymer bysolvent evaporation after collection of droplet from device is solidified to generate the microparticle. The particle size can becontrolled by tuning the flow rate and the size of the microchannel. The monodispersity of the PCL particles is measured by a coefficient of variation (CV) below 5%. 단분산성 마이크로입자는 약물캡슐화 및 전달을 위한 다양한 응용분야에서 사용되고 있다. 미세유체장치는 매우 균일한 액적을 생산할 수 있는 중요한 장치이며 이 액적은 단분산성 마이크로입자를 생성할 수 있는 중요한 템플레이트(template)로의 역할을 한다. 미세유체장치는 마이크론 크기의 채널로 구성되어 표면장력과 점성력 간의 균형을 정교하게 조절할 수 있으며, 이는 단분산성 액적을 형성하는 필수적인 기술 중의 하나이다. 본 연구는 유동집적채널 기반의 미세유체장치에서 매우 균일한 polycaprolactone (PCL) 생분해성 고분자 입자를 제조하는 방법을 제안한다. 유동집적채널 기반의 미세유체장치는 polydimethylsiloxane (PDMS) 기반의 소프트리소그래피(soft-lithography) 방법을 통해 제작된다. 액적 생성에서 중요한요소는 마이크로 액적의 크기와 단분산성을 조절하는 것이다. 이를 위해, 본 연구에서는 이 미세유체장치에서 오일용액 분산상과 수용액 연속상의 부피유속을 제어하여 단분산성 액적 형성 조건을 최적화하였다. 그 결과 균일한 액적을 형성할 수있는 dripping 영역에 대한 최척화된 유속조건을 확인하였다. 그런 다음, 마이크로입자를 생성하기 위해 PCL 고분자를 포함한 액적을 장치에서 형성한 후 용매의 증발에 의해 입자화 하였다. 입자의 크기는 부피유속과 미세유체채널의 크기에 의해조절되며 입자의 단분산도는 변동계수(coefficient of variation, CV)값이 5% 이하로 제어될 수 있다.

Fabrication of Selective Anti-Biofouling Surface for Micro/Nanopatterning of Proteins

정헌호,이지혜,이창수,장홍철,양영헌,김온환,허강무 한국고분자학회 2010 Macromolecular Research Vol.18 No.9

This paper reports a simple method for creating a functionalized surface for the efficient micro/nanopatterning of proteins by micromolding in capillaries (MIMIC) of poly(ethylene glycol)-poly(lactide) diblock copolymer (PEG-PLA) and self-assembled polyelectrolyte multilayers (PEL). The fabricated surface consisted of two distinct regions: a PEL region to promote protein immobilization and a PEG-PLA background as a biological barrier to prevent the nonspecific binding of proteins. When the ability of anti-biofouling of PEG-PLA was compared with the most widely used blocking agents, such as bovine serum albumin (BSA) and skim milk, the PEG-PLA prevents the nonspecific adsorption of several proteins. The properties of a functionalized surface were characterized by the water contact angle and atomic force microscopy (AFM). Topological analysis clearly indicated that the MIMIC method provides a reliable surface regardless of the micro- and nanopattern size. Two different functionalities of the fabricated surface produce uniform protein patterns from the micro- to nanoscale with a high signal to noise ratio. The proposed method allows for flexibility in forming shapes, such as lines, squares, circles, triangles and stars, and can control the pattern size from 400 nm to 90 μm. Finally, the antigen-antibody assay showed good linearity over the range of 10 ng/mL to 25 μg/mL, indicating its feasibility for a quantitative measurement of the concentration of target proteins in a sample.

Microfluidic-assisted Production of Photocurable Polycaprolactone Microparticles for Efficient Treatment of Oily Wastewater

펑,정헌호 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

Generation of Uniform Agarose Microwells for Cell Patterning by Micromolding in Capillaries

정헌호,이지혜,노영무,김윤곤,이창수 한국고분자학회 2013 Macromolecular Research Vol.21 No.5

We described a simple and facile method to generate uniform agarose microwells on a polyelectrolyte (PEL) multilayer functionalized surface for efficient and reliable cell patterning. The PEL multilayers, composed of polyallylamine hydrochloride (PAH) and polystyrene sulfonate ammonium (PSS), provide an adhesive environment,which promotes cell proliferation in live cell-based assays. Agarose microwells, which are able to selectively isolate cells into individual compartments, are fabricated by micromolding the agarose solution in capillaries (MIMIC). Moreover, the fabricated agarose microwells are able to effectively form different shapes (e.g., circles,triangles, squares, and stars) and can isolate multiple cell types (e.g., HEK 293, NIH3T3, and HepG2). We also demonstrated how this technique can be used for the real-time monitoring of communication between primary neuronal cells in the agarose microwells.

전해질 고분자 코팅 표면을 이용한 세포칩 제작

정헌호(Heon-Ho Jeong),송환문(Hwan-Moon Song),이창수(Chang-Soo Lee) 한국청정기술학회 2011 청정기술 Vol.17 No.1

유동-집속 생성기의 병렬화를 통한 에멀젼 생산속도 향상

정헌호 ( Heon-ho Jeong ) 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.5

Droplet-based microfluidic device has led to transformational new approaches in various applications including materials synthesis and high-throughput screening. However, efforts are required to enhance the production rate to industrial scale because of low production rate in a single droplet generator. In here, we present a method for enhancing production rate of monodisperse droplets via parallelization of flow-focusing generators. For this, we fabricated a three-dimensional monolithic elastomer device (3D MED) that has the 3D channel structures in a single layer, using a double-sided imprinting method. We demonstrated that the production rate of monodisperse droplet is increased by controlling the flow rate of continuous and dispersed phases in 3D MED with 8 droplet generators. Thus, we anticipate that this microfluidic system will be used in wide area including microparticle synthesis and screening system via encapsulation of various materials and cells in monodisperse droplets.

PDMS와 고분자 전해질 표면을 이용한 간편한 세포 패터닝 방법

정헌호(Heon-Ho Jeong),송환문(Hwan-Moon Song),황예진(Ye-jin Hwang),황택성(Taek-Sung Hwang),이창수(Chang-Soo Lee) 한국생물공학회 2009 KSBB Journal Vol.24 No.6

This study presented facile method of cell patterning using fabricated PDMS patterns on polyelectrolyte coated surface. This basic principle is the fabrication of functional surface presenting two orthogonal surfaces such as cell adhesive and repellent properties. Cell adhesive surface was firstly fabricated with simple coating of polyelectrolyte multilayer. And then, the desired patterns of PDMS for the prevention of nonspecific binding of cells were transferred onto the previously formed thin film of polyelectrolyte multilayer. Thus, we could prepare novel functional surface simultaneously containing PDMS and polyelectrolyte region. As expected, the PDMS regions showed effective prevention of nonspecific binding of cell and the other region, exposed polyelectrolyte area, provided cell adhesive environment. The height of formed PDMS structure was about 100 nm. Based on this method, cell patterning can be successfully obtained with various pattern shapes and sizes. Therefore, we expect that this simple method will be useful platform technology for the development of cell chip, cell based assay system, and biochip.

PDMS 블레이드 코팅법을 이용한 종이-기반 바이오센서칩 제작

정헌호 ( Heon-ho Jeong ),박차미 ( Chami Park ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1

This paper proposes the polydimethylsiloxane (PDMS) blade coating method for fabrication of paperbased analytical device (PAD) that is able to monitor the disease diagnosis and progress without special analytical equipment. The mold that has PAD design is easily modified by using laser cutting technique. And the fabricated mold is used for hydrophobic barrier formation by blade coating. We have optimized the stable formation of PDMS hydrophobic barrier as blade coating condition, which is established by analyzing the structure of the PDMS hydrophobic barrier and change of hydrophilic channel size as thickness of the ink and contact time with the chromatography paper. Based on optimal condition, we demonstrate that PAD as biosensor can apply to detect protein, glucose, and metal ion without special analysis equipment.