My research in the past can be summarized into the following four themes.
First, Ionic and Molecular Recognition based on Electrochemistry.
Second, Miniaturized Biosensors
Third, Chemical Modification of Solid Surfaces
Fourth, Liquid-Liquid Interface Electrochemistry

Now, my on-going and future projects are,
First, Microfludics on Microchips.
Second, Nanotube and Nanofiber Electrochemistry

2. Miniaturized Biosensors
I have worked on development of needle-type enzyme-based sensor for continuous monitoring glucose. Microfabrication technology was applied to fabricate microbiosensor arrays.

1. T.D. Chung, R.-A. Jeong, S.K. Kang and H.C. Kim
"Reproducible Fabrication of Miniaturized Glucose Sensors: Preparation of Sensing Membranes for Continuous Monitoring"
Biosensors & Bioelectronics, 16(9-12), 1079-1087 (2001). [Full Text]
2. H. Yang, T.D. Chung, Y.T. Kim, C. A. Choi, H.C. Kim
"Glucose sensor using a microfabricated electrode and electropolymerized bilayer films"
Biosensors & Bioelectronics, in press.
3. T.D. Chung, R.-A. Jeong, S.K. Kang and H.C. Kim
"Electropolymerized bilayer combining highly selective polymers and perfluorinated tetrafluoroethylene: Fabrication of continuous monitoring glucose sensors without using non-aqueous solvents"
Anal. Chem. Submitted
4. T.D. Chung, H.C. Kim, S.B. Choi and H.K. Lee
20th Annual International Conference of the IEEE 98 Engineering in Medicine and Biology Society, "Biomedical Engineering Towards the Year 2000 and Beyond", pp. 1868-2871 Hong Kong, Oct. 30, 1998.[Abstract]

In addition, 1 patent (1999) was filed.

3. Chemical Modification of Solid Surfaces
When photo- or e-beam lithography employs chemically amplifying resist(CAR), the mechanism of diffusion of the acid generated in the polymer layer needs to be understood and modeled. I established the detailed diffusion mechanism in CAR layers and rationalized the various phenomena from E-beam lithography. On the other hand, the procedure of silicon direct-bonding(SDB) was improved by optimizing the composition of oxidant solution. In addition, chemically modification of polysilicon surfaces with inert chemicals was suggested to prevent silicon building blocks from irreversible stictions.

1. Y.-M. Ham, W.-K. Lee, S.-H. Kim, T.D. Chung and K. Chun
J. Kor. Phys. Soc. 33, s67 (1998).
2. Y.-M. Ham, K.-H. Baik, W.-K. Lee, T.D. Chung and K. Chun
J. J. Appl. Phys. 37, 6761 (1998).
3. B.H. Kim, T.D. Chung, J. Lee, Y.J. Lee and K. Chun
J. Kor. Phys. Soc. 33, s450 (1998).[Full Text]
4. B.H. Kim, C.H. Oh, T.D. Chung, K. Chun, J. Byun and Y. Lee
Proceedings of MEMS 99, Jan. 19 (1999) Orlando, U.S.A.
5. B.H. Kim, T.D. Chung, C. H. Oh, K. Chun
J. MicroElectroMechanical Systems 10, 33 (2001).[Full Text]

4. Liquid-Liquid interface electrochemistry
Voltammetric study on ionic transfer across liquid-liquid interfaces provides valuable intuition on thermodynamic and kinetic principle in nature. In terms of dioxygen reduction with electrocatalysts such as metalloporphyrins, there has been a big hurdle to trigger electrocatalyses on solid electrodes. Once porphyrins are immobilized by adsorption onto solid electrodes, the excellent activity in biological systems disappears seriously. But recent reports demonstrated that an several tens micron-thick oil layer on the electrode figures out the problem of sluggish electron transfer from electrode to electrocatalysts. A key problem remained is how fast proton and oxygen are supplied across this thin oil film system during the faradaic process. This new system of liquid-liquid interface has been explored.

1. T.D. Chung and F.C. Anson
Anal. Chem. 73(2), 337 (2001).[Full Text]
2. T.D. Chung and F.C. Anson
J. Electroanal. Chem. 508, 115-122 (2001).[Full Text]
3. F.C. Anson and T.D. Chung
"Catalysis of the Electroreduction of O2 by Metalloporphyrins Dissolved in Thin Layers on Graphite Electrodes"
Pittcon 2001, New Orleans, March 6, 2001.

5. Microfluidics on microchips and Nano-electrochemistry
J. Michael Ramsey group at Oak Ridge National Laboratory has been working on developement of microfludics technology for microanalytical systems built on small chips. This technology is the core of the first commercialized Lab-on-a-chip product manufactured by Caliper and Agilent companies. Recently, a new project has started with the goal of developing automatic bioassay in sub-nanoliter volume faster than 1 Hz. The same microfluidic control technology is expected to realize combinatorial syntheses and drug screening in liquid phases on glass chips at an unbelievable speed. Now, I'm carrying out my own project of developing a electrically driven pump by which field-free flow control is achieved. In order to establish more concrete methodology, I suggested a new method to measure the fluid velocity in microchannel and successfully demonstrated it works very recently. In addition, a new concept of decoupler for monolithic amperometric detector was invented and we are on the way to collect experimental data in detail. I believe you will be able to see the results of my work here in this fall through presentation at a relevant conference.
On the other hand, I am also involved in applications of nanotubes and nanofibers as probes mornitoring chemical secretion from living cells in vivo. We are in the precess of fabrication of nanofiber with properties that we want. I promise to introduce them to you soon.

1. T.D. Chung, S.C. Jacobson, C.T. Culbertson and J.M. Ramsey
"A simple method for velocimetry of the flow in microchannel using conventional single point detection setup."
in preparation.
2. T.D. Chung, S.C. Jacobson, C.T. Culbertson and J.M. Ramsey
"An electroosmotic micropump generating field-free flow in microchannels"
in preparation.
3. T.D. Chung, S.C. Jacobson, C.T. Culbertson and J.M. Ramsey
"Oil decoupler for electrochemical detection from electroosmotically-driven microflow"
in preparation.

As long as your eyes and ears are on science and technology, I am always one of your friends whoever you are!