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Jaewon Chung
Name
Name Jaewon Chung | Associate Professor
Tel
+82-2-3290-3374
Fax
+82-2-926-9290
E-mail
jwon@korea.ac.kr
address
Department of Mechanical Engineering Korea University, Anam-dong, Sungbuk-gu, Seoul 136-713 Korea
Education
1995. 08 B.S. Mechanical Engineering, Yonsei University, Seoul, Korea
1997. 08 M.S. Mechanical Engineering, Yonsei University, Seoul, Korea
2002. 05 Ph.D. Mechanical Engineering, University of California, Berkeley
Lab.
Nano Thermo Fluidics Laboratory
Inkjet Printing and EHD printing for Flexible Electronics
Direct writing method appeared to be an attractive alternative to the semiconductor fabrication process. Among many direct writing methods, the drop on demand (DOD) inkjet process has gained significant interest due to the reduced number of process step, which is directly related to the manufacturing cost. However, the currently achievable minimum feature size is about tens of micrometers, so that its application is limited. Recently, electrohydrodynamic (EHD) printing has received considerable attention because of its potential for high resolution printing. EHD printing is a method of generating droplet by using electric force. In order to adapt EHD printing to the industrial applications in the future, there are still many issues to be resolved, such as drop on demand (DOD) EHD jet ejection, individual controllability of multi-nozzle by electric signal only, integration of the nozzle and the bottom electrode, and so on. In our laboratory, the following research is under investigation.
▶ Evaluate the performance of the electrohydrodynamic prinitng technique for Drop-On-Demand (DOD) Direct Write applications
▶ Designing the optimized DOD Direct Writing System.
Opto Eletro Wetting
Eelectrowetting has received increasing interests because of its fast switching response and low power consumption. The surface tension between the solid–liquid interface is modified by external electric field, which reduces the contact angle. Examples of electrowetting-based microfluidic systems include optical switches, digital microfluidic circuits, and liquid lenses with variable focal length. Transport of liquid in droplet forms offers many advantages. It eliminates the need for pumps and valves, has no moving parts, and is free of leak and unwanted mixing. For Lab-on-a-chip applications, several fluidic functions, such as liquid injection, transportation, mixing, and separation, need to be integrated on a single chip. For a general purpose fluidic chip that is capable of manipulating multiple droplets simultaneously requires a two-dimensional array of electrodes to control the local surface tension. However, this results in a large number of electrodes that presents a challenge for both control and packaging of such chips. Related to this, we are developing a novel mechanism for light actuation of liquid droplets. This is realized by integrating a photoconductive material underneath the electrowetting electrodes.
Optical Tweezing
Recently, one-dimensional nanostructures, such as nanowires, nanorods, nanotubes, etc. are applied in many areas, including nanoelectronic devices, optical devices, bio sensors, chemical sensors, etc. To fabricate nano-devices using these nanostructures, it is crucial to manipulate and assemble nanostructures into a designed pattern. Related to this, the optical tweezers have drawn attention, because nanostructures can be directly trapped and manipulated by the focused laser beam without special patterning process. Since optical tweezers were introduced by A. Ashkin, micro/nano particles11) and biological samples have been manipulated by using pN to sub-μN force generated on the focal point of a single laser beam. In addition, the recent employment of rapidly scanning mirror and spatial light modulator (SLM) facilitated complex multiple optical trapping, so that the optical tweezing technique is becoming more versatile. In our lab, the manipulation of nanodevices using optical tweezing is under investigation.