Gas Phase Electronic Sensing Using Single Wall Carbon Nanotube / Boipolymer Hybrids
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1057-II16-04
Gas Phase Electronic Sensing Using Single Wall Carbon Nanotube / Boipolymer Hybrids Samuel M Khamis1, Michelle Chen2, and A.T. Charlie Johnson3 1 Physics and Astronomy, University of Pennsylvania, 209 S 33rd Street, Philadelphia, PA, 19104 2 Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, 19104 3 Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, 19104 ABSTRACT We report on a class of hybrid sensors involving single-walled carbon nanotube field effect transistors (SWNT FET’s) functionalized with various oligonucleotides. These oligonucleotides include ten sequences of single-stranded DNA (ss-DNA) and two sequences of single-stranded RNA (ss-RNA). We show that the sequence of the adsorbed oligonucleotide is the key component in determining the response that the hybrid will experience upon exposure to a panel of five volatile organic compounds (VOC’s). Our sensors present a change in conductance, which is specific to the analyte being tested, and the adsorbed species. Our devices respond and recover quickly (seconds), and are reproducible over 100s of cycles. These traits are highly desirable for the creation of a technology for to be used as an electronic nose. We present a database of responses involving hundreds of devices. INTRODUCTION Single-walled carbon nanotubes have many properties making them ideal for use in chemical sensing. Their one-dimensional geometry, with all of the atoms on the surface, makes them very sensitive to small changes in their local electrostatic environment. Their small size (~1nm diameter) allows for fabrication of large arrays of devices over a relatively small area. Many people have taken advantage of these traits to create sensor technologies based on SWNT’s or SWNT Mats [1-4]. Many of these sensors require external refreshing such as heating, ultraviolet light treatment, or washing inorder to recover come a sensing event. We report on a class of sensors that respond and recover from successive exposures to analyte bearing Ar flow, and pure Ar flow with no need of external refreshing. Recently there has been great interest in tuning the chemical affinity of SWNT FET’s by both covalent and non-covalent functionalization means [5,6]. Covalent functionalization is less desirable because excessive breaking of C-C bonds in the nanotube lattice can degrade the electronic properties of the device [7]. Single-stranded species of both deoxyribonucleic (ssDNA) and ribonucleic acids (ss-RNA) represent a class of materials known to strongly interact with π-conjugated systems such as single walled carbon nanotubes. This so called π-π stacking interaction allows us to non-covalently attach chemical binding sites to our devices thus preserving their pristine electronic characteristics. Recent experiments have shown that these materials offer a remarkable set of technologically useful properties such as facilitation of SWNT sorting [8], chemical sensing [5,9] and detection of DNA hybridization [10,11]. Staii et al. studied two sequence
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