MEMS/NANO
MEMS/NANO
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Summary
Over the past several decades, the application of microelectronic technology to mechanical engineering has resulted in an irreversible shift in the research of sensors and actuators. The microelectromechanical systems (MEMS) technology makes use of miniaturization, semiconductor materials, and batch processing to solve age-old problems existed in mechanical engineering. In addition, continued research in nanoscale engineering is leading to new technological base and infrastructure that will have major impact on mechanical engineering. The extraordinary versatility of MEMS and nanoengineering technology promises the development of new-concept devices (including sensors and actuators) with increased capabilities and improved performance-to-cost ratio, which far surpass conventional engineering solutions. Our laboratory is committed to the development of MEMS and nanoengineering. Some key projects of research are as follows.
Microneedles for drug delivery
A robust method for fabricating mass-customizable master molds is developed to prepare sharp-tipped biodegradable polymer microneedles. Our approach combines the predrying and chip casting (PCC) of an ultrathick photoresist layer with a substrateless, inclined, and rotational exposure (SIR exposure). The PCC achieves the uniform reduction of solvent across the photoresist thickness which is critically required for the formation of a sharp tip; the SIR exposure creates master molds whose geometry is easily customizable and virtually insensitive to a variation in ultraviolet (UV) exposure dose. A theoretical model for the spatiotemporal distribution of UV dose under SIR exposure is established to show the technological superiority of our method.
Researcher funders and partners
National Research Foundation of Korea (NRF)
Photocurable polymer nanocomposites containing nanofillers
The spatial patterning of photocurable polymer nanocomposites (PnCs) with electrical conductivity provides high flexibility in fabricating microscale conductors on surfaces of any geometry. Here, we establish a theoretical model on the phtopatternable thickness of photocurable PnCs containing carbon-based high-aspect-ratio (HAR) fillers. Our model is derived by modifying the Beer-Lambert law to fully consider UV light absorption and reflection in the fillers, after describing HAR fillers as spherical ones with an out-of-plane orientation parameter. The accuracy of the proposed model is verified by comparing the predicted results with the experimental data on graphite nanoflake (GnF)-reinforced SU-8 PnCs, GnF/SU-8 PnCs.
Researcher funders and partners
Agency for Defense Development (ADD), National Research Foundation of Korea (NRF), Hanwha Aerospace, University of Hawaii at Manoa (UH Manoa)
Piezoresistive high-g accelerometers
A set of piezoresistive high-g accelerometers are designed, microfabricated, and characterized to achieve high shock endurance, low cross-axis sensitivity, and high microfabrication yield. The technical features and advances in the accelerometer are as follows. First of all, the cross-symmetric structure is introduced to the accelerometer to reduce cross-axis sensitivity. Secondly, the piezoresistors implanted on the elastic beam surface at a low doping level are adopted for high gauge factor, high sensitivity, and excellent shock endurance. Last but not least, the cross-symmetric structure, generating both tensile and compressive stresses on the elastic beam surface, forms piezoresistor bridge interconnection on a single side of accelerometer, which is intended to simplify the microfabrication processes (including wiring and packaging).
Researcher funders and partners
Agency for Defense Development (ADD), Korea Advanced Institute of Science and Technology (KAIST), JMJ Korea
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