Katsuyuki Murata

Calibration method for a carbon nanotube field-effect transistor biosensor

An easy calibration method based on the Langmuir adsorption theory is proposed for a carbon nanotube field-effect transistor (NTFET) biosensor. This method was applied to three NTFET biosensors that had approximately the same structure but exhibited different characteristics. After calibration, their experimentally determined characteristics exhibited a good agreement with the calibration curve. The reason why the observed characteristics of these NTFET biosensors differed among the devices was that the carbon nanotube (CNT) that formed the channel was not uniform. Although the controlled growth of a CNT is difficult, it is shown that an NTFET biosensor can be easy calibrated using the proposed calibration method, regardless of the CNT channel structures.

Comparison of sensitivities of carbon nanotube field-effect transistor biosensors with and without top metal gate

The sensitivities of biosensors using top-gate-type carbon nanotube field-effect transistors (CNT-FETs) with and without a top metal gate were compared. The CNT-FET biosensor without the top metal gate (sensor I) showed about three times higher transconductance than the one with the top metal gate (sensor II) when they were modulated by a reference gate electrode placed in a solution. Further, the sensitivity of sensor I was three times higher than sensor II. These results were attributed to the shielding effect of the top metal gate electrode placed in the solution, which was proved by a numerical simulation.

Room-Temperature Carbon Nanotube Single-Electron Transistor with Defects Introduced by La(NO3)3 Process

The new fabrication process for a carbon nanotube (CNT) single-electron transistor (SET) operated at room temperature was proposed using La(NO3)3. The carbon nanotube reacts with oxygen included in La(NO3)3 at high temperature and the defects that worked as tunnel junctions were introduced. For consistency CNT-SET shows Coulomb oscillation and Coulomb diamond characteristics at 300 K. From the simulation, it was found that the newly proposed process introduced three effective defects into CNT, and CNT-SET worked as two islands SET.

Dependence of sensitivity of biosensor for carbon nanotube field-effect transistor with top-gate structures

In this study, we used biosensors that employ a top-gate-type carbon nanotube field-effect transistor (CNT-FET) for detecting target proteins in a solution. The dependence of the sensitivity of the biosensor on structural characteristics of the top gate, such as the thicknesses of its insulator and electrode and the relative permittivity of the insulator, was examined by simulations and by experiment which change the thickness of the insulator. Results of calculations performed by the finite element method showed that a thin insulator with a relative permittivity greater than 20 would lead to high sensitivity of the CNT-FET biosensor. Experimental investigation supported this result. The transconductance of a CNT-FET with a 20-nm-thick insulating layer was found to be approximately six times higher than that with 50-nm-thick and 80-nm-thick insulating layers. Moreover, the sensitivity of the CNT-FET biosensor with the 20-nm-thick insulating layer was also higher than that of a CNT-FET with a thicker insul...

First Selective Detection of Proteins Using Top-Gate Carbon Nanotube Field Effect Transistor

Olympus Corporation, 2-3-1 Nishishinjuku, Shinjukiu, Tokyo 163-0914, Japan Phone: +81-29-861-5080-30059 E-mail: masu-abe@aist.go.jp NEDO, 1310 Omiyacho, Saiwai, Kawasaki, Kanagawa 212-8554, Japan CREST-JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan Mitsubishi Kagaku, 1000 Higashimamianacho, Ushiku, Ibaraki 300-1295, Japan Mitsubishi Kagaku Iatron, 1144 Ohwadashinden, Yachiyo, Chiba 276-0046, Japan AIST, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan Osaka Univ., 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan