(559i) Chemoresistive Responses of Functionalized SWNTs

There is need for advanced synthetic molecular chemoreceptors in the design and development of all electronic Natural Olfactory Sensor Emulators® (NOSEs)[1]. Carbon nanotubes with their semiconducting properties and relative ease of non-covalent and covalent functionalization are well suited for chemoreceptor use in e-Noses[2]. A series of functionalized SWNTs rationalized on the basis of covalent chemical modification to impart electron-donating or electron-withdrawing functionalities have been synthesized and characterized[3]. These derivatized-nanotube-based materials are designed to serve as chemoreceptors that can facilitate the development of highly selective and sensitive chemical and biological sensor arrays through an “electronic nose” approach which mimics the mammalian olfactory system[4]. Functionalized SWNTs (f-SWNTs) were dispersed in dimethyl formamide (DMF) and cast onto the interdigit space of microlithographically fabricated, pre-cleaned interdigitated microsensor electrodes (IME 1025-M-Pt). Devices were 10 mm line and space with 25 fingers of Pt(100nm)/TiW(20nm) patterned on borosilicate glass. Devices were solvent cleaned and chemically modified with octadecyltrichlorosilane (OTS), cathodically cleaned (20 cycles, 100 mV/s, PBS 7.2), rinsed with isopropyl alcohol and dried in flowing argon. The resulting devices (receptors) were characterized by two–electrode impedance spectroscopy (20 mV p-t-p; 10^-1 – 10⁶ Hz; RT) and equivalent circuit modeling in various gases/vapors[5]. We compare the EIS profiles when the same chemoresistive f-SWNT layer was cast onto gold vs. platinum devices. We compare the EIS profiles when the same chemoresistive f-SWNT layer was cast onto IME devices that were unmodified or chemically modified with octadecyltrichlorosilane (OTS). The chemo-resistive responses to these same gases/vapors were determined under DC conditions by continuous monitoring following flow injection of gas/vapor.

Keywords: chemoresistors, nanotubes, olfaction, impedance

References:

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