title: Suspended graphene sensors with improved signal and reduced noise.
abstract: We report enhanced performance of suspended graphene field effect transistors (Gra-FETs) as sensors in aqueous solutions. Etching of the silicon oxide (SiO(2)) substrate underneath graphene was carried out in situ during electrical measurements of devices, which enabled systematic comparison of transport properties for same devices before and after suspension. Significantly, the transconductance of Gra-FETs in the linear operating modes increases 1.5 and 2 times when the power of low-frequency noise concomitantly decreases 12 and 6 times for hole and electron carriers, respectively, after suspension of graphene in solution from the SiO(2) substrate. Suspended graphene devices were further demonstrated as direct and real-time pH sensors, and complementary pH sensing with the same nanodevice working as either a p-type or n-type transistor was experimentally realized by offsetting the electrolyte gate potential in solution. Our results highlight the importance to quantify fundamental parameters that define resolution of graphene-based bioelectronics and demonstrate that suspended nanodevices represent attractive platforms for chemical and biological sensors.
authors.affiliation: National Center for Nanoscience and Technology, 11 Beiyitiao Street, Zhongguancun, Beijing, People's Republic of China.
authors.forename: Zengguang
authors.initials: Z
authors.lastname: Cheng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Li
authors.forename: Qiaoyu
authors.initials: Q
authors.lastname: Zhou
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D014173:Transistors, Electronic
chemical_list: D006108:Graphite