Sensors SWNT network

Regardless of whether pm-ification or modification steps are employed liquid deposition of allows the formation of SWNT networks on a wide variety of substrates at room temperature without the use of complicated equipment. Further, these networks can be formed on transparent substrates like glass or plastic quickly (17,86-89). This property results in numerous novel sensor applications and such devices are expected to have a huge impact on the electronics industry in general (18,90-95). 

SWNT networks formed from aqueous suspensions of carbon nanotubes have proved to be rrsefirl for a variety of sensor apphcations. Figure 4 demonstrates how these networks can be used for sensing a variety of volatile organic vapors. Saturated vapors of each of the analytes were added to a flowing stream of purified air in order to determine the response of the carbon nanotube network. 

Single wall carbon nanotube (SWNT) network sensors were prepared as previously described (7-9). The carbon nanotube network (CNN) sensors were spray coated with a 0.1% by weight solution of polymer to a thickness of approximately 100 nm. These CNN sensors can be monitored simultaneously in capacitive and resistive mode. The capacitance was measured by applying a 0.1 V, 30 kHz, AC voltage between a conducting Si substrate and a S T network deposited on a thermal SiOa layer. The induced AC current was measured using a Stanford Research Systems SR830 lock-in amplifier. 

Composite films of CNTs with other materials, such as conducting polymers or ceramics, are very fascinating materials for the development of electrochemical sensors. Yang and co-workers fabricated an electrode via electropolymerization of acid chrome blue K at an MWNT-functionalized glassy carbon electrode for simultaneous determination of dihydrox-ybenzene isomers in real water samples through applying the first-order linear sweep derivative voltammetry. Polypyrrole (PPy) or polyaniline (PANI) was electrochemically deposited on SWNT networks by Ferrer-Anglada and co-workers ° in 2006, which has been used as solid-state pH sensors. 

Chemical and Genetic Probes—Nanotube-tipped atomic force microscopes can trace a strand of DNA and identify chemical markers that reveal DNA fine structure. A miniaturized sensor has been constructed based on coupling the electronic properties of nanotubes with the specific recognition properties of immobilized biomolecules by attaching organic molecules handles to these tubular nanostructures. In one study, the pi-electron network on the CNT is used to anchor a molecule that irreversibly adsorbs to the surface of the SWNT. The anchored molecules have a tail to which proteins, or a variety of other... 

The use of hquid deposited networks of aligned SWNTs in sensing apphcations presents a new frontier in the creation of lightweight and flexible sensor device stmctnres. This allows the formation of devices composed of either two electrodes or of arrays of interdigitated electrodes. 

An array of sensors having random network of SWNTs... 

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