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High-stability sensing of proteins of pig serum albumin (PSA) was achieved using an insulator-covered carbonnanotube field-effect transistor (CNT-FET) with a top-gate structure. The sensitivity limit of this CNT-FET PSA sensor is at least 5 nmol/L PSA solution. A layer of silicon nitride deposited on the top-gate structure provides an n-type characteristic and a highly stable CNT-FET. Since the CNT is covered with a silicon nitride layer, it is isolated from oxygen, water, and other contaminants. The equilibrium constant of the PSA/ anti-PSA reaction, which indicates the strength of the binding energy between PSA and anti-PSA fixed on the Au top-gate electrode, was calculated to be 1.2 × 10 7 L/mol using the Langmuir equation fitting.

The effect of the selective adsorption of pig serum albumin as an antigen on the electrical properties of a carbon nanotube channel field effect transistor on which anti-pig serum albumin was immobilized as an antibody by physisorption in phosphate buffer solution has been investigated. We have succeeded in real-time detection of the adsorption of pig serum albumin on anti-pig serum albumin as a decrease in the conductance of the carbon nanotube channel field effect transistor, by a label-free process.

Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product.

The control of the growth direction of a carbon nanotube was accomplished by applying an electric field during the growth of the carbon nanotube. The effects of two types of applied bias, one is a constant DC bias, and the other is a ramp bias, on the control of the growth direction were examined. By maintaining a constant DC bias we could control the growth direction of the carbon nanotube, however, the bridging ratio between the two electrodes was as small as 35%. We suppose that this low bridging ratio may be caused by the etching effect of hydrogen. When a ramp bias was applied, bridging ratio tended to increase with the slope of ramp bias. Under optimal conditions, the bridging ratio reached a value as high as 95%.

The air stable n-type carbon nanotube channel filed effect transistor (CNT-FET) with the top gate structure was successfully fabricated using the silicon nitride gate insulator deposited by the thermal chemical vapor deposition. The effects of the silicon nitride insulator on the electrical properties of the CNT-FET have been investigated. The p-type characteristics of the CNT-FET can be converted to the n-type characteristics in high yield of 90% only by depositing the silicon nitride insulator. The drain current is as high as few µA order. The n-type top gate CNT-FET stably operated even in ambient air.

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