DNA-decorated Graphene Chemical Sensors

Graphene is a two-dimensional material with exceptional electronic properties and enormous potential for applications. Graphene’s promise as a chemical sensor material has been noted but there has been little work on practical chemical sensing using graphene, and in particular, how chemical functionalization may be used to sensitize graphene to chemical vapors. Here we show one route towards improving the ability of graphene to work as a chemical sensor by using single stranded DNA as a sensitizing agent. The resulting devices show fast response times, complete and rapid recovery to baseline at room temperature, and discrimination between several similar vapor analytes. Disciplines Physical Sciences and Mathematics | Physics Comments Suggested Citation: Lu, Y., B.R. Goldsmith, N.J. Kybert, and A.T.C. Johnson. (2010). DNA-decorated graphene chemical sensors. Applied Physics Letters. 97, 083107. Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters and may be found at http://dx.doi.org/10.1063/ 1.3483128. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/5 DNA-decorated graphene chemical sensors Ye Lu, B. R. Goldsmith, N. J. Kybert, and A. T. C. Johnson Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd St., Philadelphia, Pennsylvania 19104-6396, USA Received 21 May 2010; accepted 28 July 2010; published online 26 August 2010 Graphene is a two-dimensional material with exceptional electronic properties and enormous potential for applications. Graphene’s promise as a chemical sensor material has been noted but there has been little work on practical chemical sensing using graphene, and in particular, how chemical functionalization may be used to sensitize graphene to chemical vapors. Here we show one route towards improving the ability of graphene to work as a chemical sensor by using single stranded DNA as a sensitizing agent. The resulting devices show fast response times, complete and rapid recovery to baseline at room temperature, and discrimination between several similar vapor analytes. © 2010 American Institute of Physics. doi:10.1063/1.3483128 Graphene has been actively studied as a chemical sensor since shortly after it was isolated in 2004. Increasingly sophisticated device processing has revealed that early measurements of graphene exhibited chemical sensing responses that were amplified by unintentional functionalization. Here, we start with chemically clean graphene transistors that are inert to a variety of chemical vapors. We then purposefully functionalize the graphene to generate devices with different chemical sensing responses. We demonstrate that graphene can be combined with single stranded DNA ssDNA to create a chemically diverse family of vapor sensors that is promising for use in a “noselike” vapor sensing system. Noselike sensing schemes derive their organizational principle from biological olfactory systems, where a relatively small number 100 s of sensor types are deployed with broad and overlapping sensitivities to a much larger number of volatile analytes. In our DNA-graphene sensor system, ssDNA is not used for its biological functionality but instead provides sequence-dependent chemical recognition capability, potentially enabling the required number hundreds of chemically distinct sensor responses. Reduced graphene oxide, or “chemically derived grapheme,” has also shown potential as a vapor sensor material where residual oxygen defects e.g., carboxylic acids or epoxides provide binding sites for analyte molecules. Graphene transistors were constructed using exfoliated kish graphite on silicon substrates with a 300 nm oxide layer. Devices were carefully cleaned to prevent spurious sensing results, then functionalized with a self-assembled layer of ssDNA as done previously for carbon nanotube devices. Two ssDNA sequences “sequence 1” and “sequence 2” were selected because of their prior use in vapor sensors based on electronic and optical fluorescence readout strategies Sequence 1: 5 GAG TCT GTG GAG GAG GTA GTC 3 , Sequence 2: 5 CTT CTG TCT TGA TGT TTG TCA AAC