Professor of Chemical Engineering
Professor of Materials Science and Engineering
BS., Yonsei University, Korea, 1990
MS., Yonsei University, Korea, 1992
Ph.D., Northwestern University, 1998
Korea Research Institute of Chemical Technology
University of California, Berkeley
Office: N323 Millennium Science Complex
Phone: (814) 863-4809
N256A Millennium Science Complex
N213A Millennium Science Complex
N030B Millennium Science Complex
MEMS: An end to fear of contact
Micro-Electro-Mechanical Systems or MEMS are found in a variety of consumer products ranging from inkjet printers and the accelerometers that deploy your car's airbags, to the tiny gyroscopes that sense the movement of your Nintendo Wii or the way you rotate your iPhone.
Since MEMS are on the nanoscale, when we try to build systems with gears or other moving parts friction and lubrication become an issue. The February 2010 Tribology & Lubrication Technology Journal features an article that discusses the work of the Seong Kim Research Group as they attempt to develop a viable lubricant for Micro-Electro-Mechanical Systems (MEMS).
Download the "MEMS: An end to fear of contact.pdf" from the February 2010 issue of Tribology & Lubrication Technology Journal.
Seong Kim earns "Professor" of Chemical Engineering
Congratulations to faculty member Seong Kim who was recently promoted to Professor of Chemical Engieering.
Surface Science in Nanotribology
Nanoscale Surface Engineering and Chemical Imaging
An overview of Prof. Seong Kimís research
Prof. Seong H. Kim joined the faculty of Chemical Engineering in 2001 after completing a Ph.D. study in Chemistry from Northwestern University and a post-doctoral research at University of California, Berkeley. His research interests lie in surface science and nano-engineering. Since he moved to Penn State, Dr. Kimís group has opened and established new research frontiers that have not been done previously:
(i) fundamentals and applications of molecular lubrications by adsorbed molecules in ambient conditions,
(ii) nanofabrication of organic functional materials via reactions-at-place,
(iii) conducting polymer nanofibers and biocatalytic nanofibers,
(iv) superhydrophobic coatings through one-step atmospheric plasma processes,
(v) understanding and controlling the initiation of propagation of surface defects on multicomponent silicate glasses, and
(vi) non-linear optical characterization of meso-scale assembly of cellulose microfibrils in plant cell walls and lignocellulose biomass.
He has 140 peer-reviewed journal publications and his current h-index is 29 as of January 2014. http://scholar.google.com/citations?sortby=pubdate&hl=en&user=HQnqr3oAAAAJ&view_op=list_work
Dr. Kim's group single-handedly invented an effective lubrication method for microelectro-mechanical systems (MEMS), resolving the reliability issue of MEMS devices with moving and sliding mechanical parts. Before he started this research, the MEMS tribology/lubrication field focused on organic or hard coatings to solve the adhesion and wear problems. Although those approaches solved static adhesion problems, they did not prevent the wear problem. Dr. Kim realized the importance of continuously replenishing lubricant molecules at the interface without causing any viscous power dissipation and devised an idea of employing thermodynamic equilibrium of alcohol vapor adsorption on solid surfaces. To date, the vapor phase lubrication is one of the most reliable lubrication methods for MEMS devices with moving parts. In order to understand the vapor phase lubrication mechanism, his group carried out extensive research on vapor adsorption isotherm using spectroscopic characterizations and attained molecular insights into how adsorbates on solid surfaces influence mechanical contacts of solids in ambient conditions. The molecular layers adsorbed on solid surfaces in ambient conditions have tremendous effects on adhesion, friction, and wear properties of solid materials. Although these phenomena have been well documented in the literature, little was known about physical mechanisms through which they affect interfacial mechanical properties. Kimís group showed that the water layer adsorbed on silicon oxide assumes a 'solid-like' hydrogen-bond network structure at low humidity conditions and the liquid-like structure grows only at high humidity. The physical mechanism for capillary force was elucidated through careful experimental measurements as well as theoretical calculations. Their work was highlighted in a Feature Article in Langmuir [pubs.acs.org/doi/abs/10.1021/la402856j].
Recently, Kim group launched a major research program studying glass surface science, in collaboration with Prof. Carlo Pantano in Department of Materials Science and Engineering. The theoretical strength of oxide glasses is estimated to be on the order of 14 GPa; but the practical strength is two or three orders of magnitude lower than the theoretical value. This is mainly due to defects at the glass surfaces, but fundamental understanding of glass surface chemistry is very limited. Kimís group found that the friction and wear measurements are very sensitive to chemical reactions at glass surfaces, especially water activities at multicomponent glass surfaces. By combining various surface mechanical property measurements and surface-sensitive spectroscopic analyses [onlinelibrary.wiley.com/doi/10.1111/jace.12136/full], his group brings new insights into surface science fundamentals of chemical and mechanochemical behaviors of silicate glasses which are by far the most important materials for the US glass industry.
Another major development in recent years is new frontiers of analytical study of hierarchical structure of cellulose, crystalline nanomaterials synthesized by plants, certain bacteria, and a sea animal (tunicate). In collaboration with various researchers in the Penn State Center for Lignocellulose Structure and Formation (CLSF) which is one of the DOEís Energy Frontier Research Centers (EFRC), his group discovered that vibrational sum-frequency-generation (SFG) spectroscopy can be used to probe native cellulose structures in plant cell walls. Recently, interests in cellulose have been growing significantly due to its potential as renewable recourses for production of transportation fuels or other valuable materials. Its viability for such applications greatly depends on the structure and three-dimensional assembly of crystalline cellulose microfibrils in plant cell walls (industrially called biomass), which are not well understood yet. The currently accepted models for cellulose crystal structures are constructed based on x-ray and electron diffraction and nuclear magnetic resonance analyses of isolated and purified cellulose samples. Although these previous works greatly contributed to the structural understanding of cellulose crystals, the existing models are not sufficient for full understanding of native cellulose and its roles in plant growth, physical properties, and recalcitrance to chemical and enzymatic degradation processes. This is in part due to the lack of proper characterization techniques that can relate structural information at various length scales: crystallographic unit cell of cellulose at nanoscale, three dimensional assembly of cellulose microfibrils and their association with matrix wall polymers in cell walls at mesoscale (between nm and µm), and phenotypes of plants at macroscale. Thus, Kimís seminal work applying SFG analysis to cellulose [www.plantphysiol.org/content/163/2/907.short] is critical for deeper understanding of native cellulose in intact plant cell walls and biomass. New insights from these studies will elucidate native cellulose crystal structures and packing in plant cell walls and guide development of efficient biomass degradation processes for sustainable engineering.