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Sensors 2016, 16(10), 1481;

Graphene Nanogrids FET Immunosensor: Signal to Noise Ratio Enhancement

Electronics and Telecommunication Engineering Department, Indian Institute of Engineering Science and Technology, Howrah 711103, India
Author to whom correspondence should be addressed.
Academic Editor: Meyya Meyyappan
Received: 11 May 2016 / Revised: 11 August 2016 / Accepted: 19 August 2016 / Published: 8 October 2016
(This article belongs to the Special Issue Carbon MEMS and NEMS for Sensor Applications)
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Recently, a reproducible and scalable chemical method for fabrication of smooth graphene nanogrids has been reported which addresses the challenges of graphene nanoribbons (GNR). These nanogrids have been found to be capable of attomolar detection of biomolecules in field effect transistor (FET) mode. However, for detection of sub-femtomolar concentrations of target molecule in complex mixtures with reasonable accuracy, it is not sufficient to only explore the steady state sensitivities, but is also necessary to investigate the flicker noise which dominates at frequencies below 100 kHz. This low frequency noise is dependent on the exposure time of the graphene layer in the buffer solution and concentration of charged impurities at the surface. In this paper, the functionalization strategy of graphene nanogrids has been optimized with respect to concentration and incubation time of the cross linker for an enhancement in signal to noise ratio (SNR). It has been interestingly observed that as the sensitivity and noise power change at different rates with the functionalization parameters, SNR does not vary monotonically but is maximum corresponding to a particular parameter. The optimized parameter has improved the SNR by 50% which has enabled a detection of 0.05 fM Hep-B virus molecules with a sensitivity of around 30% and a standard deviation within 3%. Further, the SNR enhancement has resulted in improvement of quantification accuracy by five times and selectivity by two orders of magnitude. View Full-Text
Keywords: graphene nanosensor; FET; immunosensor; low frequency noise; sensitivity; cross linker; optimization graphene nanosensor; FET; immunosensor; low frequency noise; sensitivity; cross linker; optimization

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Basu, J.; RoyChaudhuri, C. Graphene Nanogrids FET Immunosensor: Signal to Noise Ratio Enhancement. Sensors 2016, 16, 1481.

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