TAKAMURA Laboratory
<Major Research Areas>Micro fluidic devices, biochips, nano-fabrication, plasma

Study of Next-generation
Biochips by Nano-fabrication

Research activity

　　Research is rapidly advancing in the area called “π-TAS (micro total analysis systems)” or “labs on a chip”, which are micro fluidic devices that enable complex chemical experiments, such as blood tests, to be conducted on a chip containing microfluidic channels, reactors, and analyzers on the wafer by applying semiconductor technology. These research results can be applied to medical diagnosis, drug discovery, and understanding of life, and are expected to open up a large commercial market and new academic fields. In nano channels, the behavior of large molecules in fluid and fluid itself are greatly influenced by Brownian motion and the properties of interfaces, and include new phenomena that cannot be dealt with by fluid dynamics or molecular dynamics. Our laboratory aims to design the next generation of biochips, which will combine nano science and biochemistry based on research of these new phenomena. Our main research themes are outlined below.

1Selective trapping of bio molecules through tapered channels

　　When DNA flows into a tapered channel as shown in Figure 1, and electric and pressure fields are applied in opposite directions, long DNA is selectively trapped at the narrow point of the channel. We investigate this trapping phenomenon, and also conduct applied research including gene expression analysis of single cells.

2Development of highly functional biochemical chips with integrated microfluidic devices and novel detectors

　　An on-chip precise flow control system and highly sensitive detectors are urgently required to realize highly functional biochips. We are developing various fluid drive mechanisms on chips, including electroosmotic flow and novel detectors using nanomaterials. By combining these techniques, we are developing general-purpose biochemical microfluidic chips for which it is possible to modify the program of the process sequences of biochemical reactions according to use, any number of times. (Figure 2). We expect these biochips to promote research fields related to solution nanotechnology-especially biochemistry and life science.

3Development of micro elemental analyzer using liquid electrode plasma

　　When a liquid sample is injected into a micro channel that is narrow at the center, and high voltage is applied, plasma is generated. The types and quantities of elements in the sample can be easily and highly sensitively measured from the spectra of the light emitted from the plasmas. Based on this principle, we are developing micro elemental analyzers that enable on-site analysis of hazardous heavy metals (Hg, Cd, Pb, etc.) contained in environment, food, water, soil, and waste from factories.

Equipment

Electron-beam lithography, mask aligner, magnetron sputter, dry etcher, fluorescent microscope, spectrometer, electrochemical analyzer, scanning probe microscope

The main research achievements in the past five years

1. N. Ba Trung, M. Saito, H. Takabayashi, P. Hung Viet, E. Tamiya and Y. Takamura, Multi-chamber PCR chip with simple liquid introduction utilizing the gas permeability of polydimethylsiloxane, Sensors and Actuators B : Chemical, 149 (1), 284-290(2010).
2. Y. Tomizawa, E. Tamiya, and Y. Takamura, Trapping probability analysis of a DNA trap using electric and hydrodrag force fields in tapered microchanels, Phys. Rev. E, 79, 051902, (2009).
3. M. Banno, E. Tamiya, and Y. Takamura, Determination of trace amounts of sodium and lithium in zirconium dioxide (ZrO₂ ) using liquid electrode plasma optical emission spectrometry, Anal. Chim. Acta, 634, 153-157 (2009).
4. Y. Tsujita, K. Maehashi, K. Matsumoto, M. Chikae, S. Torai, Y. Takamura, and E. Tamiya, Carbon nanotube amperometric chips with pneumatic micropumps, Jpn. J. Appl. Phys., 47, 2064-2067 (2008).
5. K. Maehashi, T. Katsura, K. Kerman, Y. Takamura, K. Matsumoto, and E. Tamiya, Label-free protein biosensor based on aptamer-modified carbon nanotube field-effect transistors, Anal. Chem., 79, 782-787 (2007).