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Simple haptotactic gradient generation within a triangular microfluidic channel
Park, Jungyul,Kim, Deok-Ho,Kim, Gabriel,Kim, Younghoon,Choi, Eunpyo,Levchenko, Andre Royal Society of Chemistry 2010 Lab on a chip Vol.10 No.16
<P>Most microfluidic devices developed to date for the analysis of live cells incorporate channels with relatively simple constant rectangular or semi-circular cross-sections, relying on complex channel network geometries rather than alteration of the shapes of the channels themselves for development of diverse functional fluidic controls, <I>e.g.</I>, spatial gradients of bioactive ligands. In this study we describe a simple alternative method to create highly defined and predictable gradients of surface bound molecules. This method relies on the generation of a considerable variation in the spatial distribution of flow velocities within a channel with a triangular cross-section. The triangular shape can be easily implemented by using bulk wet etching and polydimethylsiloxane (PDMS) replica molding techniques. By analytical modeling and simulation, we predict that the deposition of the solute onto a channel boundary depends on the local flow rate values, yielding gradient spanning the whole width of the channel. This prediction was validated by direct visualization of the flow rate and fibronectin–rhodamine deposition in a fabricated microchannel. Using this experimental platform, we assessed cell migration in response to a fibronectin gradient deposited in the microchannels. We find that this gradient could induce robust haptotaxis of Chinese Hamster Ovary (CHO) cells towards the areas of higher fibronectin surface density. We propose that the described simple gradient generation method can help to avoid complexity present in many current device designs, allowing to introduce more easily other potentially useful design features.</P> <P>Graphic Abstract</P><P>In this study we describe a simple alternative method to create highly defined and predictable gradients of surface bound molecules. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b924222h'> </P>
Identification and control of a sensorized microgripper for micromanipulation
Park, Jungyul,Kim, Sangmin,Kim, Deok-Ho,Kim, Byungkyu,Kwon, Sang Joo,Park, Jong-Oh,Lee, Kyo-Il IEEE 2005 IEEE/ASME transactions on mechatronics Vol.10 No.5
This paper presents the design and control of a sensorized microgripper using a voice coil motor and a flexure mechanism. To increase the gripping sensitivity, shape design and determination of sensor attachment position are performed using finite element analysis. Empirical models of the microgripper are acquired for the design of position control and gripping force control. By using the identified models, both the perfect tracking controller for position control and the adaptive zero-phase error tracking controller for force control are implemented. The effectiveness of the proposed model-based control methods is verified by experimental studies.
Epidemiology and Clinical Patterns of Ocular Trauma at a Level 1 Trauma Center in Korea
Park Jungyul,Yang Sang Cheol,최희영 대한의학회 2021 Journal of Korean medical science Vol.36 No.1
Background: To evaluate the patterns of distribution and clinical manifestations of ocular injuries referred to the level 1 trauma center of Pusan National University Hospital (PNUH) in Korea. Methods: We analyzed 254 of 4,287 patients who were referred to the Department of Ophthalmology at the level 1 trauma center of the PNUH, from January 2016 through December 2018. Data on the incidence of ocular injuries, sex, age, monthly and seasonal distribution, day and time of injury, side of injury, cause, residence of patients, referral time to an ophthalmologist and subsequent examination time, final visual acuity (VA), and complications were obtained from medical records and retrospectively reviewed. The patients were grouped according to their main diagnosis using the Birmingham Eye Trauma Terminology System (BETTS) and Ocular Trauma Score (OTS). Results: The incidence of ocular injuries with major trauma was higher in men (n = 207, 81.5%), the median age at time of injury was 54 years, and Pusan recorded the most cases. The incidences of ocular injury were 1.47/100,000, 1.57/100,000, 1.48/100,000 in 2016, 2017 and 2018, respectively. The most common cause was by a motorbike accident, followed by a pedestrian traffic accident and falls. According to the BETTS classification, open-globe injuries represented 4% of cases, closed-globe injuries represented 12.6%, and other injuries represented 83.1%. Open-globe injuries were significantly associated with low final VA (P = 0.01). In the OTS, 79.4% of patients received 4 or 5 points and 13.7% of patients received 1 or 2 points. The patients who received 1 or 2 points in the OTS score showed final VA below hand movement (P < 0.001), except for two patients. Lid laceration and low initial VA were highly correlated with poor final VA (P < 0.001).Conclusion: This is the first study on the epidemiology and clinical manifestations in trauma patients with ocular injuries at a level 1 trauma center. The incidences of ocular injuries with major trauma were about 1.47–1.57/100,000. BETTS, OTS, lid laceration and initial VA were associated with final VA. We expect our study to provide a basis of data for the evaluation, prevention, and management of ocular injuries in patients with systemic trauma.
Mechanotransduction of cardiomyocytes interacting with a thin membrane transducer
Park, Jungyul,Kim, Il Chaek,Cha, Jaemin,Park, Sukho,Lee, Junghoon,Kim, Byungkyu IOP 2007 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.17 No.6
<P>A novel platform is developed to study the mechanotransduction of cardiomyocytes. After the cardiomyocytes are seeded on 10 ?m thin, dome-shaped membranes with different sizes, their morphology and beating frequency are monitored. While the cells seeded on a larger membrane (800 ?m ? 800 ?m) grow normally, cells on a smaller membrane (200 ?m ? 200 ?m) grow in isolated groups, showing a lumped morphology. The beating frequency of the cells on the smaller membrane was faster than on the larger membrane. This intriguing phenomenon may be explained by the mechanical stress determined by the area of the membrane that affects the opening of ion channels.</P>
Design and Performance Evaluation of a 3-DOF Mobile Microrobot for Micromanipulation
Park, Jungyul,Kim, Deok-Ho,Kim, Byungkyu,Kim, Taesung,Lee, Kyo-Il The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.9
In this paper, a compact 3-DOF mobile microrobot with sub-micron resolution is presented. It has many outstanding features : it is as small as a coin ; its precision is of sub-micrometer resolution on the plane ; it has an unlimited travel range ; and it has simple and compact mechanisms and structures which can be realized at low cost. With the impact actuating mechanism, this system enable both fast coarse motion and highly precise fine motion with a pulse wave input voltage controlled. The 1 -DOF impact actuating mechanism is modeled by taking into consideration the friction between the piezoelectric actuator and base. This modeling technique is extended to simulate the motion of the 3-DOF mobile robot. In addition, experiments are conducted to verify that the simulations accurately represent the real system. The modeling and simulation results will be used to design the model-based controller for the target system. The developed system can be used as a robotic positioning device in the micromanipulation system that determines the position of micro-sized components or particles in a small space, or assemble them in the meso-scale structure.
Design and Performance Evaluation of a 3-DOF Mobile Microrobot for Micromanipulation
Jungyul Park,Deok-Ho Kim,Byungkyu Kim,Taesung Kim,Kyo-Il Lee 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.9
In this paper. a compact 3-DOF mobile microrobot with sub-micron resolution is presented. It has many outstanding features: it is as small as a coin; its precision is of sub-micrometer resolution on the plane; it has an unlimited travel range; and it has simple and compact mechanisms and structures which can be realized at low cost. With the impact actuating mechanism, this system enable both fast coarse motion and highly precise fine motion with a pulse wave input voltage controlled. The I-DOF impact actuating mechanism is modeled by taking into consideration the friction between the piezoelectric actuator and base. This modeling technique is extended to simulate the motion of the 3-DOF mobile robot. In addition, experiments are conducted to verify that the simulations accurately represent the real system. The modeling and simulation results will be used to design the model-based controller for the target system. The developed system can be used as a robotic positioning device in the micromanipulation system that determines the position of micro-sized components or panicles in a small space, or assemble them in the meso-scale structure.
Jungyul Park 대한뇌혈관외과학회 2023 Journal of Cerebrovascular and Endovascular Neuros Vol.25 No.3
Carotid-cavernous fistulas, characterized by abnormal arteriovenous communication within the cavernous sinus (CS), can be classified as direct or indirect. Direct fistulas are defined as a direct connection between the internal carotid artery (ICA) and CS, whereas indirect fistulas result from an abnormal connection between the CS and dural arterial branches. The first-line treatment for both types of fistulas is endovascular intervention, most commonly accomplished through the transarterial and transvenous approaches of the conventional pathway, including the ICA, inferior and superior petrosal sinuses, or basilar plexus. Nonetheless, a retrograde approach through the superior ophthalmic vein may be necessary for individuals in whom conventional endovascular treatment fails. Herein, the current principles of surgical indication and technique are presented, along with case studies.