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Abstract: Aptamer-immobilized gold nanoparticles (AuNP)/single-walled carbon nanotube (SWNT) field effect transistor (FET) sensors are fabricated for the detection of the ErbB2 protein. The 5′-thiol-modified 40-mer naphthyl DNA aptamers are immobilized on the AuNPs using well-established thiol chemistry. Carbodiimidazole-activated tween 20 (CDI-tween 20) layers are also introduced to the surface of the SWNT via hydrophobic interactions for blocking the attachment of nonspecific substances. Quantitative experiments reveal the specific binding effect of ErbB2 on the electrical measurements by comparing the electrical responses from a non-specific binding and control aptamer experiments. Under the optimized experimental conditions, the ErbB2 protein is clearly detectable at concentrations as low as 10pM. The self-gating effect of the present device with a concentric electrode is able to provide a reliable electrical measurement scheme by circumventing the limits related to the isoelectric point of the target protein. Furthermore, the sensor fabrication, treatment and detection method have the potential to meet the following requirements: simplicity, portability, low cost and no need for bulky optical instruments. [Copyright &y& Elsevier]

The integration of carbon nanotube (CNT)-based sensor and readout complementary metal–oxide–semiconductor integrated chip (CMOS IC) to detect hydrogen gas in a single chip is presented. First, we have fabricated the CMOS IC using the standard 0.35-\mu \m CMOS process. Then, we have built 8 \times 8 CNT-based sensor cells on it using a proposed tractable postprocessing strategy and judicious electrode scheme. The fabricated sensor IC can operate down to 10-ppm concentration of hydrogen in air as a hydrogen sensor. This paper is expected to have a major impact upon the integration of the CNT technology with CMOS technology and be extended to the development of CMOS IC integrated with various nanomaterials. [ABSTRACT FROM AUTHOR]

A carbon nanotube network device having concentric-shaped electrodes (source and drain) is analyzed to examine the “self-gating” effect of various pH buffer solutions on its electrical properties. Using the 2-D homogeneous percolation theory, current–voltage characteristics of the devices are described as the classical MOSFET formula, in which the device is modeled as the p-type transistor with positive threshold voltage and the gate is tied with the drain (at positive bias) or source (at negative bias). To determine the apparent threshold voltage change due to the corresponding pH value, the \partial VD/\partial ID (VD: drain voltage; ID: drain current) curve is extracted from the measured current–voltage characteristics to find VD\SAT (= - VTH, VGS = \0). A threshold voltage shift according to the pH value is observed without an external gate electrode, showing the possibility of relaxing the requirement of the external gate electrode. By grafting protonation/deprotonation which occurs in the carboxylated single-walled carbon nanotubes, the decaying current as pH increases is explained. Better sensitivity according to the operation regime is examined by the device modeling. [ABSTRACT FROM PUBLISHER]