Single-stranded DNA decorated carbon nanotube transistors for chemical sensing Cristian Staii 1 , Michelle Chen 2 , Alan Gelperin 3 , Alan T. Johnson, Jr. 1 1 Department of Physics and Astronomy and Laboratory for Research on the Structure of Matter, University of Pennsylvania, 209 South 33 rd Street, Philadelphia, Pennsylvania 19104 2 Department of Material Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104 3 Monell Chemical Senses Center, 3500 Market Street, Philadelphia, Pennsylvania 19104 ABSTRACT We demonstrate that single walled carbon nanotube field effect transistors (swCN-FET) decorated with single stranded DNA (ss-DNA) form a new, versatile, and highly sensitive class of nanoscale chemical sensors. These sensors are based on ss-DNA as the chemical recognition site and swCN-FET as the electronic read-out component. The ss-DNA decorated swCN-FETs are sensitive to chemical species (odors) that do not cause a detectable response in bare, as- fabricated swCN-FETs. Furthermore, odor responses ss-DNA decorated FETs differ in sign and magnitude for different odors, and the response characteristics depend on the base sequence of the ss-DNA used to decorate the swCN. The sensor surface is self-regenerating: samples maintain a constant response with no need for sensor refreshing through at least several dozens gas exposure cycles. These remarkable attributes suggest that DNA-decorated swCN-FET sensors could be created with sensitivity to a large variety of compounds, as required for “electronic-nose” and “electronic tongue” applications in medicine and homeland security. INTRODUCTION Semiconducting swCNs are one-dimensional carbon cage structures where every atom and electronic state lies on the surface of the tube [1]. Their physical properties are thus extremely sensitive to variations in the surrounding electrostatic environment, whether the swCNs are suspended in liquid or incorporated into field effect transistors (FET) circuits on a substrate [2- 4]. Although bare swCNs are reported to be sensitive to various gases, some even at the part-per- billion level [5-7], swCNs functionalized with biomolecular complexes on their outer surface hold great promise as new molecular probes and sensors [8, 9], targeted for chemical species that interact weakly or not at all with unmodified nanotubes. Derivatized swCN-FETs and semiconductor nanowires are equally attractive as electronic-readout molecular sensors due to their high sensitivity, fast response time, and compatibility with dense array fabrication [4, 10]. A major challenge to developing useful swCN-based sensors is the need to controllably tailor the surface of swCNs to direct their electronic interaction with particular gaseous or liquid analytes. Although various schemes to achieve this goal have been presented, none have simultaneously achieved robust and reproducible decoration of the swCN, along with molecular flexibility promising sensitivity to a wide spectrum of analytes. Non-covalent functionalization is strongly preferred so as not to degrade the geometry of the nanotube atomic bonding, which is directly responsible for its high-quality electronic properties. 0900-O08-08.1 Mater. Res. Soc. Symp. Proc. Vol. 900E © 2006 Materials Research Society