Research

What is Biophotonics?
 
The capability for biosensing, biomedical imaging, and biomolecular manipulation has become essential in current biomedical research and development. Light is very attractive in that it can be utilized for all these functions. Biophotonics is the study of light interaction with biological matter and it is also recently regarded as the key science for the next generation of clinical tools and biomedical research instruments. This research area, however, is still in need for advanced biomedical imaging techniques, highly sensitive biophotonic sensors, and massive/rapid biomolecular manipulation methods.
 
For last decade, a remarkable achievement in nano/microscale manufacturing of engineering materials has been rapidly stimulated by MEMS and NEMS (Micro/Nano Electro-Mechanical systems) technology and moreover high sensitive metrological techniques at micro/nanoscale lead physiologists to deeper understanding on the working mechanism of physiological structures in nature.
 
 
Prof. Ki-Hun Jeong’s Research Statement at KAIST

Ki-Hun Jeong is currently an associate professor in the department of Bio and Brain Engineering at KAIST in Korea, as well as an associated director at KAIST Institute for Optical Science and Technology. He received a Ph.D. in mechanical engineering from the University of California at Berkeley in 2005 after a B.S. and M.S. degree in mechanical engineering from Sungkyunkwan University in 1996 and 1998. After a post-doctoral position in the department of electrical engineering at UC Berkeley in 2005-2006, he joined at KAIST as an assistant professor in the department of bio and brain engineering in 2006.
 
His previous research interests during PhD (Adviser: Prof. Luke P. Lee in BioE) and post-doctoral (Adviser: Prof. Ming C. Wu) studies at UC Berkeley were the design, microfabrication, and measurement of biophotonic MEMS for biomedical applications such as biomimetic advanced photonic devices [1-7], nanomechanical biophysical sensors [8-10], nanogap based dielectric spectroscopic biosensors [11-16], and MEMS endoscopes. In particular, his main achievement on biomimetic advanced photonic systems was published in Science in 2006, entitled as “Biologically Inspired Artificial Compound Eyes”. This work received huge attentions from over 40 international/Korean News media. This work provides a new paradigm for developing wide field-of-view imagingor motion detection in surveillance detectors, mini-robots, and miniaturized imaging systems such as endoscopes, digital cameras or mobile phones.

His current research interests at KAIST include Optical MEMS and nanophotonics that can be inspired from biology and also utilized for advanced biological science or biomedical applications. After he joined at KAIST as an assistant professor, his academic backgrounds on photonic design, diverse micro/nanofabrication, and photonic measurements have been modified and stimulated to focus on the following three specific topics among broad biophotonic areas, also aligned with the personal academic strength as well as the long term objectives of the department of bio and brain engineering at KAIST. For last four years of 2007-2010, he achieved 4 SCI journal papers, 1 domestic review paper, 42 domestic and international conference proceedings, 43 domestic and international invited talks, 11 Korea and PCT patent filings, and 1 technology licensing.

His major focused areas of research are as follows,
A. Biologically inspired photonics at small scale
B. Nanobioplasmonics
C. Microendoscopy
 
 
Biologically inspired photonics at small scale is the main extension of his PhD research at KAIST. This research topic covers the engineering biomimetics of insect’s natural photonic structures for vision, bioluminescence, and camouflage. First, the insect’s vision scheme such as natural compound eyes successfully inspired 3D artificial compound eyes during his PhD [1, 2]. This work has been further developed for high resolution 3D artificial compound eye, which can be utilized for wide field-of-view endoscopic imaging system or mobile camera modules [17]. Recently he demonstrated biologically inspired optical circuits that can implement ten different vision schemes of natural compound eyes [18]. This work is currently being used for developing novel optical touch sensor arrays on next generation display module with Samsung electronics [19]. The US and Korean patent applications have been filed in the country IP office [20, 21]. Second, the insect’s bioluminescence such as firefly’s light organ can inspire next generation LED based illumination system. The anatomical and photonic structures have been mimicked and employed for wide angle LED lens [22]. The PCT and Korean patent applications have also been filed [23, 24] and this technical licensing has been transferred to a lighting company called BLUEN Ltd.[25]. Currently, he is consulting the company for the mass production of the LED lens. He presented four invited talks at international conferences, especially in IEEE Optical MEMS and Nanophotonics 2009, Clearwater, FL, USA [26], entitled as “biologically inspired optical structures for wide field-of-view imaging and wide angle illumination”. This opportunity reflects that his group becomes one of the leading groups in a field of biologically inspired photonics. Based on the previous achievements, he has been awarded a $1.3 million National Research Foundation (NRF) grant for research on bioinspired nanophotonics: mimicking insect’s vision, bioluminescence, and camouflage [27].

Nanobioplasmonics is his newly focused area at KAIST. The department of bio and brain engineering at KAIST is actively boosting the field of neuroscience-focused bioengineering. For interdepartmental collaboration, he expanded his background for highly sensitive biophotonic sensing of small molecules, which are particularly related to neurodegenerative diseases such as Alzheimer. In technical point-of-view, his group has developed novel fabrication methods for hierarchical photonic structures by incorporating conventional microfabrication methods with diverse nanofabrication methods such as colloid lithography, nanoimprint lithography, soft lithography, e-beam lithography, and aluminum anodic oxidation, which are also in need for the above topic, i.e., biologically inspired photonics at small scale. For last four years, the platform technologies have been employed with metal nanostructures, i.e., nanoplasmonics devices for highly sensitive SERS detection of small molecules such as neurotransmitters. The recent achievement on nanobioplasmonics is featured as a cover article in SMALL [28]. The SERS has been widely used for biomolecular detection at low concentration. However, small molecules such as neurotransmitters are much less Raman scattered and the current limit of Raman detection is only at micromolar level. His recent work reported the technical conjunction between nanofluidics and nanoplasmonics that allows the Raman detection of major neurotransmitters at nanomolar level. This method has huge potential for initiating the label-free bioassay, clinical, or pharmaceutical applications to discover small molecules such as cell signaling molecules, pharmaceuticals, metabolites, and many other natural or artificial organic compounds at a low concentration level. In particular, he is currently working on advancing this method to detect beta-amyloids at nanomolar level from human cerebrospinal fluids of Alzheimer patients. 

Microendoscopy is his long-term focused area at KAIST. From the main achievement of the above two topics, the biophotonic sensing techniques and novel photonic devices are being employed for functional endoscopic imaging system. Laser scanning is of great interest in miniaturized endoscopic systems. His recent achievement is the development of MEMS lens scanning modules for forward endoscopic imaging systems [29]. Before the journal publication, this work was awarded the best paper at Korea MEMS conference and also presented as an Oral at IEEE Optical MEMS and nanophotonics conference 2010, Sapporo, Japan. This work is being developed for 3D endoscopic imaging based on Optical Coherence Tomography (OCT). Another contribution to integrated biophotonic MEMS is the development of Miniaturized Terahertz Bioimaging Systems, which has been financially supported by the Korea evaluation institute of industrial technology (KEIT) for five years (2008-2012) with a $1.7M research grant [30]. Five co-principle investigators from KAIST and Korea research institute of Standards and Science (KRISS) have a strong collaboration for this project. His contribution is to develop the THz MEMS endoscope catheter, which includes THz photoconductive antenna for THz wave generation and detection, large scale MEMS mirrors for THz wave scanning, and microoptical benches for endoscope packaging. Based on this activity in Korea [31], He published an invited article in Journal of Korean Institute of Electromagnetic Engineering and Science (JKIEES), entitled “Merging MEMS with Terahertz waves” [32].

In summary, he has focused on MEMS/NEMS enabled biophotonics at KAIST for last four years, particular in bioinspired photonics, nanobioplasmonics, and integrated biophotonics. Currently he advises nine graduate students and one postdoctoral researcher with fully developed lab facilities thanks to affordable research grants. The annual personal research grants have been increased every year from 2007 to 2010. The total research grants during the period are $2.6M and this year he holds $579K research grants. (For reference, KAIST average annual research grants per PI amounts to $227K). His group is leading in biophotonics areas in the department of bio and brain engineering at KAIST, domestically in biophotonic MEMS areas, and internationally in biologically inspired photonics areas.


Reference

[1] K. Jeong, J. Kim, and L.P. Lee, Biologically Inspired Artificial compound eyes, Science, vol. 312 (5773), 2006 LINK
[2] J. Kim*, K. Jeong *, and L. P. Lee, Artificial ommatidium by microlens-induced self-writing of waveguide, Optics Letter, vol.30, no.1, pp.5-7, 2005 * equal contribution on this publication LINK
[3] Paul Hung, K. Jeong, G.L. Liu, and L. P. Lee, Microfabricated suspensions for electrical connections on the tunable elastomer membrane, Applied Physics Letter, vol.85, no. 24, pp.6051-6053, 2004. LINK
[4] K. Jeong, G. L. Liu, N. Chronis, and L. P. Lee, Tunable microdoublet lens array, Opt. Express 12, pp.2494-2500, 2004 LINK
[5] N. Chronis, K. Jeong, G. L. Liu, and L. P. Lee, Tunable Liquid Microlens Array Integrated on Microfluidic Network, Optics Express, vol. 11, no.19, pp.2370-2378, 2003 LINK
[6] K. Jeong, and L. P. Lee, A Novel Microfabrication of A Self-Aligned Vertical Comb Drive On A Single SOI Wafer For Optical MEMS Applications, J. Micromechanics and Microengineering, vol. 15, pp 277-281, 2005 LINK
[7] K. Jeong, and L. P. Lee, A New Method of Increasing Numerical Aperture of Microlens for Biophotonic MEMS, The 2nd annual international IEEE-EMBS special topic conference on microtechnologies in medicine & biology 2002, Madison, USA LINK
[8] K. Jeong, C. G. Keller, L. P. Lee, Direct Force Measurements of Biomolecular Interactions by Nanomechanical Force Gauge, Applied Physics Letters, vol.86, no.17, 2005 LINK
[9] D. Di Carlo, K. Jeong, and L. P. Lee, Reagentless mechanical cell lysis by nanoscale barbs in microchannels for sample preparation, Lab on a Chip, 3(4), pp.287-291, 2003 LINK
[10] K. Jeong, S. B. Oh and L.P. Lee, Hydrophobic sealing for integrated microactuators in biofluidic system, Proceedings of the microTAS symposium, p.157-158, Monterey, CA, USA, 2001 LINK
[11] M. Yi, K. Jeong, and L. P. Lee, Electrical Double Layer Interaction within Nanogap, Biosensors and Bioelectronics, vol.20, no. 7, pp. 1320-1326, 2005 LINK
[12] J. T. Nevill*, D. Di Carlo*, P. Liu, K. Jeong, and L. P. Lee, Detection Of Protein Conformational Changes With A Nanogap Biosensor, Transducers 2005 LINK
[13] J. T. Nevill, K. Jeong, and L. P. Lee, Ultrasensitive Nanogap Biosensor to Detect Changes In Structure Of Water And Ice, Transducers 2005 LINK
[14] D. Di Carlo, H. Kang, Z. Xianghui, K. Jeong, L. P. Lee, Nanogap-based dielectric immunosensing, Transducers 2003 Boston, USA LINK
[15] S. B.Oh, J. S. Lee, K. Jeong, L. P. Lee, Minimization of electrode polarization effect by nanogap electrodes for biosensor, MEMS 2003, Kyoto, Japan LINK
[16] J. Lee, M. Pio, K. Jeong, and L. P. Lee, Sensitive In-Situ Montoring of DNA Hybridization Using Capacitance Measurement., MRS Spring Meeting 2002, San Francisco, USA LINK
[17] H. Jung and K. Jeong, Microfabricated ommatidia using a laser induced self-writing process for high resolution artificial compound eye optical systems, Opt. Express vol. 17 no.17, pp.14761-14766, 2009 LINK
[18] D. Keum and K. Jeong, Direct visualization of light propagation inside a planar artificial compound eye using a Rhodamine 6G doped photosensitive polymer resin, Clearwater Beach, USA, IEEE Optical MEMS and Nanophotonics 2009 LINK
[19] Principal investigator K. Jeong, Development of optical touch module on LCD panel, Research grant $68K, Samsung electronics, 2009.04-2010.03
[20] KR10-2009-0086359
[21] US Patent will be applied in October, 2010.
[22] J. Kim, S. Chae, and K. Jeong, Micropatterned single lens for wide-angle light-emitting diodes, Opt. Lett., vol. 35, no. 6, 2010 LINK
[23] PCT WO/2010/033002
[24] KR10-2009-0089314 and KR10-2008-0092814
[25] Technology licensing to Bluen Ltd, 2010.05 LINK

 

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