Rollable Microfluidic Systems with Microscale Bending Radius and Tuning of Device Function with Reconfigurable 3D Channel Geometry

Kim, Jihye,You, Jae Bem,Nam, Sung Min,Seo, Sumin,Im, Sung Gap,Lee, Wonhee American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.12

<P>Flexible microfluidic system is an essential component of wearable biosensors to handle body fluids. A parylene-based, thin-film microfluidic system is developed to achieve flexible microfluidics with microscale bending radius. A new molding and bonding technique is developed for parylene microchannel fabrication. Bonding with nanoadhesive layers deposited by initiated chemical vapor deposition (iCVD) enables the construction of microfluidic channels with short fabrication time and high bonding strength. The high mechanical strength of parylene allows less channel deformation from the internal pressure for the thin-film parylene channel than bulk PDMS channel. At the same time, negligible channel sagging or collapse is observed during channel bending, down to a few hundreds of micrometers due to stress relaxation by prestretch structure. The flexible parylene channels are also developed into a rollable microfluidic system. In a rollable microfluidics format, 2D parylene channels can be rolled around a capillary tubing working as inlets to minimize the device footprint. In addition, we show that creating reconfigurable 3D channel geometry with microscale bending radius can lead to tunable device function: tunable Dean-flow mixer is demonstrated using reconfigurable microscale 3D curved channel. Flexible parylene microfluidics with microscale bending radius is expected to provide an important breakthrough for many fields including wearable biosensors and tunable 3D microfluidics.</P>

Enhancing the biocompatibility of microfluidics-assisted fabrication of cell-laden microgels with channel geometry

Kim, Suntae,Oh, Jonghyun,Cha, Chaenyung Elsevier 2016 Colloids and surfaces Biointerfaces Vol.147 No.-

<P><B>Abstract</B></P> <P>Microfluidic flow-focusing devices (FFD) are widely used to generate monodisperse droplets and microgels with controllable size, shape and composition for various biomedical applications. However, highly inconsistent and often low viability of cells encapsulated within the microgels prepared via microfluidic FFD has been a major concern, and yet this aspect has not been systematically explored. In this study, we demonstrate that the biocompatibility of microfluidic FFD to fabricate cell-laden microgels can be significantly enhanced by controlling the channel geometry. When a single emulsion (“single”) microfluidic FFD is used to fabricate cell-laden microgels, there is a significant decrease and batch-to-batch variability in the cell viability, regardless of their size and composition. It is determined that during droplet generation, some of the cells are exposed to the oil phase which is shown to have a cytotoxic effect. Therefore, a microfluidic device with a sequential (‘double’) flow-focusing channels is employed instead, in which a secondary aqueous phase containing cells enters the primary aqueous phase, so the cells’ exposure to the oil phase is minimized by directing them to the center of droplets. This microfluidic channel geometry significantly enhances the biocompatibility of cell-laden microgels, while maintaining the benefits of a typical microfluidic process. This study therefore provides a simple and yet highly effective strategy to improve the biocompatibility of microfluidic fabrication of cell-laden microgels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microfluidic flow-focusing device (FFD) is used to fabricate cell-laden microgels. </LI> <LI> Cell viability is low and inconsistent when using “single” microfluidic FFD. </LI> <LI> Cytotoxic effect of oil phase used in “single” microfluidic FFD is demonstrated. </LI> <LI> “Double” microfluidic FFD can minimize contact between cells and oil phase. </LI> <LI> Cell viability is greatly enhanced using “double” microfluidic FFD. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Biocompatibility of microfluidic fabrication of cell-laden microgel is enhanced by employing “double” flow-focusing channel geometry.</P> <P>[DISPLAY OMISSION]</P>

Recent Developments in 3D Printing of Droplet-Based Microfluidics

Adedamola D. Aladese,정헌호 한국바이오칩학회 2021 BioChip Journal Vol.15 No.4

The advent of microfluidics, especially with the integration of droplet-based systems, has led to significant innovations and outstanding applications in many fields. While this field of study has grown increasingly over the years, the conventional method of fabricating these devices has discouraged their large-scale production, making their commercialization almost impossible. This is because traditional methods of producing droplet-based microfluidics are mostly time-consuming and labor-intensive and involve multiple processes. The emergence of 3D printing has found its application in microfluidics, providing an avenue for ease of fabrication with the aim of overcoming the limitations of conventional methods. While previous studies focused on studying the role of 3D printing in microfluidics, no study has categorically focused on the application of additive manufacturing to droplet-based microfluidics. This paper reviews the various 3D printing techniques associated with droplet-based microfluidics. Furthermore, we identify the salient features, limitations, and material properties of each printing technique while providing certain projections about their future application.

A microfluidic binary logic device using inertia-elastic particle focusing

양세현,윤재륜,송영석 한국물리학회 2018 Current Applied Physics Vol.18 No.9

While a few attempts have been made on microfluidic logic devices, e.g., digital microfluidics and a fluid transistor, complete integration of digitalization into microfluidics is still a challenge. In this study, we investigate a microfluidic logic device that is built based on the particle dynamics in viscoelastic fluid. A logic gate system employing a Boolean function is implemented by utilizing multiple line particle focusing behavior in the microfluidic channel. The device is designed and fabricated to hydrodynamically control the logic operations of XOR, OR, AND, Buffer, and NOT under the fixed flow condition (e.g., flow rate, particle size, and fluid elasticity∼ 1.483). In addition, numerical simulation is carried out to understand the fundamental physics of the particle and fluid behavior in viscoelastic flow. Clear multiple particle focusing lines with high separation resolution (Rij ∼ 6.19) were observed and the particle extraction at the outlets were analyzed by image-processing. This study is expected to open a new route to the incorporation of microfluidics with electronics by demonstrating logic gates based on microfluidics.

Prospects and Opportunities for Microsystems and Microfluidic Devices in the Field of Otorhinolaryngology

황세환,Alan M. Gonzalez-Suarez,Gulnaz Stybayeva,Alexander Revzin 대한이비인후과학회 2021 Clinical and Experimental Otorhinolaryngology Vol.14 No.1

Microfluidic systems can be used to control picoliter to microliter volumes in ways not possible with other methods of fluid handling. In recent years, the field of microfluidics has grown rapidly, with microfluidic devices offering possibilities to impact biology and medicine. Microfluidic devices populated with human cells have the potential to mimic the physiological functions of tissues and organs in a three-dimensional microenvironment and enable the study of mechanisms of human diseases, drug discovery and the practice of personalized medicine. In the field of otorhinolaryngology, various types of microfluidic systems have already been introduced to study organ physiology, diagnose diseases, and evaluate therapeutic efficacy. Therefore, microfluidic technologies can be implemented at all levels of otorhinolaryngology. This review is intended to promote understanding of microfluidic properties and introduce the recent literature on application of microfluidic-related devices in the field of otorhinolaryngology.

Easy module chip platform for microfluidics

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

Microfluidic technology is widely interested in many industrial fields. However, the complex and unique designs of microfluidic device is obstacle to expend its applications. Some scientists have tried to divide the complex function of microfluidic devices as several unit functional devices. However, the connectivity and the usage of the previous devices are still uncomfortable. Here we introduce an easy module chip platform for microfluidics. Each of modules are represent an unit function of microfluidic device such as Plasma separator, Valve, Mixer, DNA extractor, PCR, Sensor and etc. The module chip is consisted with a case frame, a core and silicon connectors. Module chips are easily connected and disconnected with each other using magnet force. The silicon connector is good for the liquid transportation without leakage. I believe that this module chip platform will be useful for not only researcher but also young students.

Microfluidics in nanoparticle drug delivery; From synthesis to pre-clinical screening

Ahn, Jungho,Ko, Jihoon,Lee, Somin,Yu, James,Kim, YongTae,Jeon, Noo Li Elsevier 2018 Advanced drug delivery reviews Vol.128 No.-

<P><B>Abstract</B></P> <P>Microfluidic technologies employ nano and microscale fabrication techniques to develop highly controllable and reproducible fluidic microenvironments. Utilizing microfluidics, lead compounds can be produced with the controlled physicochemical properties, characterized in a high-throughput fashion, and evaluated in <I>in vitro</I> biomimetic models of human organs; organ-on-a-chip. As a step forward from conventional <I>in vitro</I> culture methods, microfluidics shows promise in effective preclinical testing of nanoparticle-based drug delivery. This review presents a curated selection of state-of-the-art microfluidic platforms focusing on the fabrication, characterization, and assessment of nanoparticles for drug delivery applications. We also discuss the current challenges and future prospects of nanoparticle drug delivery development using microfluidics.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Inertial Microfluidics-Based Cell Sorting

김가영,한종인,박제균 한국바이오칩학회 2018 BioChip Journal Vol.12 No.4

Inertial microfluidics has attracted significant attention in recent years due to its superior benefits of high throughput, precise control, simplicity, and low cost. Many inertial microfluidic applications have been demonstrated for physiological sample processing, clinical diagnostics, and environmental monitoring and cleanup. In this review, we discuss the fundamental mechanisms and principles of inertial migration and Dean flow, which are the basis of inertial microfluidics, and provide basic scaling laws for designing the inertial microfluidic devices. This will allow end-users with diverse backgrounds to more easily take advantage of the inertial microfluidic technologies in a wide range of applications. A variety of recent applications are also classified according to the structure of the microchannel: straight channels and curved channels. Finally, several future perspectives of employing fluid inertia in microfluidic- based cell sorting are discussed. Inertial microfluidics is still expected to be promising in the near future with more novel designs using various shapes of cross section, sheath flows with different viscosities, or technologies that target micron and submicron bioparticles.

A Minireview on Inertial Microfluidics Fundamentals: Inertial Particle Focusing and Secondary Flow

정아람 한국바이오칩학회 2019 BioChip Journal Vol.13 No.1

In 1961, Segre and Silberberg first reported the tubular pinch effect and numerous theoretical studies were subsequently published to explain the inertial particle migration phenomenon. Presently, as fluid mechanics meets micro- and nanotechnology, theoretical studies on intrinsic particle migration and flow phenomena associated with inertia are being experimentally tested and validated. This collective study on the fluid-particle-structure phenomena in microchannels involving fluid inertia is called, “inertial microfluidics”. Beyond theoretical studies, now inertial microfluidics has been gaining much attention from various research fields ranging from biomedicine to industry. Despite the positive contributions, there is still a lack of clear understanding of intrinsic inertial effects in microchannels. Therefore, this minireview introduces the mechanisms and underlying physics in inertial microfluidic systems with specific focuses on inertial particle migration and secondary flow, and outlines the opportunities provided by inertial microfluidics, along with an outlook on the field.

Soft Lithography for Microfluidics: a Review

김필남,권건우,박민철,이성훈,김선민,서갑양 한국바이오칩학회 2008 BioChip Journal Vol.2 No.1

Soft lithography has provided a low-expertise route toward micro/nanofabrication and is playing an important role in microfluidics, ranging from simple channel abrication to the creation of micropatterns onto a surface or within a microfluidic channel. In this review, the materials, methods, and applications of soft lithography for microfluidics are briefly summarized with a particular emphasis on integrated microfluidic systems containing physical microstructures or a topographically patterned substrate. Relevant exemplary works based on the combination of various soft lithographic methods using microfluidics are introduced with some comments on their merits and weaknesses.