Single - Walled 14 . Single - Walled Carbon Nanotube Sensor Concepts

Carbon nanotubes are nanocomponents par excellence that offer unique properties to be exploited in next-generation devices. Sensing applications are perhaps the class that has most to gain from single-walled carbon nanotubes (SWNTs); virtually any property of SWNTs (e.g., electronic, electrical, mechanical, and optical) can result or has already resulted in sensor concept demonstrators. The basic questions that this chapter will attempt to address are: why use SWNTs, and how can SWNTs be used in sensing applications? A tour through the gallery of basic nanotube properties is used to reveal the richness and uniqueness of this material’s intrinsic properties. Together with examples from the literature showing performance of SWNT-based sensors at least comparable to (and sometimes surpassing) that of state-of-the-art microor macrodevices, these nanotube properties should explain why so much effort is currently being invested in this field. Because nanotubes, like any other nanoobject, are not easy to probe, a versatile strategy for accessing their properties, via the carbon nanotube field-effect transistor (CNFET) concept, will be described in this chapter. Fabricating CNFET devices, together with examples of SWNT sensor demonstrators utilizing the CNFET principle, will outline a proposal for how nanotubes can be utilized in sensors. In Sect. 14.1 design considerations for SWNT sensors are brought into attention, starting with 14.1 Design Considerations for SWNT Sensors . 404 14.1.1 CNT Properties for Sensing ............. 405 14.1.2 Carbon Nanotube FET Structures ..... 409 14.1.3 Sensor Characterization................. 411