1. Biomimetics (Insect Mimicked Flying Robot and Bacteria Swimming Robot)

 In the future, the micro-robot will be important in terms of applications like reconnaissance, energy harvesting, or therapy for disease. Meanwhile, many insect or micro-organism move or act interestingly as their own ways to increase the efficiency. Therefore, it is important to investigate their moving dynamics and mimic their behavior on our developed robot. So, we studied how the beetle wing flap depending on their flying status with a view of fluid-dynamics. Also, we studied how micro-organism like bacteria moves depending on external stimulus and applied it to Microbial Fuel Cells for power enhancement.

2. Surface Acoustic Wave (SAW)

 Surface Acoustic Wave (SAW) is an acoustic wave traveling along the surface of a material. It has been known as a potential actuator to manipulate liquid in the microscale regime. Especially, When the high intensity of focused surface acoustic waves come into contact with a free surface droplet, we can observe the unusual droplet jetting and jumping formation. We physically investigated this droplet jetting phenomenon. From using this technique, we developed a novel spraying and coating system for functional materials. 

3. High Resolution Printing by Electrohydrodynamic (EHD) Jet Printing

 Conventional Inkjet printing has a difficulty to enhance the pattern resolution because of the size of nozzle and the limitation of allowable viscosity range. However, the electrohydrodynamic (EHD) jet printing can eject the smaller size of droplet or jet and can eject the relatively higher viscosity ink thanks to the help of electrical shear stress acting on liquid meniscus. So, we have studied and developed the EHD jet printing technology to increase the resolution (decrease the pattern size around until 3 um, still working on increase the resolution more). Also, based on the technique we developed, we developed many printed electronics which can be applied in various electric applications.

4. Air-assited Electrospray for uniform and thin coating

 Conventional Spray coating technique, helped by shear air, has limitation to enhance the uniformity of coated film and to decrease the coating thickness for fabrication of very thin film. As a alternatives, the Electrospray, which is a way to atomize the droplet below than micro size with a help of electric-field, was introduced to fabricate the uniform and thin film. However, Electrospray was still not enough to fabricate more thin and uniform film. We developed air-assisted Electrospray coating technique, in which the droplet atomized well and more focused on the substrate to coat the liquid.

5. Terahertz Metamaterials for Sensing Applications

 The research is related to the fabrication of terahertz metamaterial sensor for the accurate and on-site detection of yeast using electrohydrodynamic jet printing, which is inexpensive, simple, and environmentally friendly. The very small sized pattern up to 5 µm-width of electrical split ring resonator unit structures could be printed on a large area on both a rigid substrate and flexible substrate, i.e. silicon wafer and polyimide film using the drop on demand technique to eject liquid ink containing silver nanoparticles. 

6. Micro/Nano-Fluidics (including Multiphysics)

 The fluid in micro-/nano-scale often has been showing interesting phenomena which is not seen in macro scale. In many applications, the fluid acts on various Multi-physical environment in order to be controlled as user's purpose. The fluid under the Multi-physical environment also often shows interesting abnormal behaviors. So, it is necessary to understand somewhat complex and interesting phenomena in order to control it well depending on various target applications. For those reasons, we now studying vaious interesting fluid-dynamics phenomena under Multiphysics in micro-/nano-scale.