Metallic-semiconducting junctions create sensing hot-spots in carbon nanotube FET aptasensors near percolation.

Autor: Thanihaichelvan M; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6021, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; Department of Physics, University of Jaffna, Jaffna 40000, Sri Lanka., Browning LA; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6021, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand., Dierkes MP; Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407, United States., Reyes RM; Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407, United States., Kralicek AV; The New Zealand Institute for Plant & Food Research Limited, Auckland 1142, New Zealand., Carraher C; The New Zealand Institute for Plant & Food Research Limited, Auckland 1142, New Zealand., Marlow CA; Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407, United States., Plank NOV; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6021, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand. Electronic address: natalie.plank@vuw.ac.nz.
Jazyk: angličtina
Zdroj: Biosensors & bioelectronics [Biosens Bioelectron] 2019 Apr 01; Vol. 130, pp. 408-413. Date of Electronic Publication: 2018 Sep 08.
DOI: 10.1016/j.bios.2018.09.021
Abstrakt: Easily fabricated random network carbon nanotube field-effect transistors (CNT-FETs) have benefitted from improved separation techniques to deliver CNTs with current formulations providing at least 99% semiconducting tube content. Amongst the most promising applications of this device platform are electronic biosensors, where the network conduction is affected through tethered probes such as aptamers which act as molecular scale electrostatic gates. However, the prevailing assumption that these biosensor devices would be optimized if metallic tubes were entirely eliminated has not been examined. Here, we show that metallic-semiconducting junctions in aptasensors are sensing hotspots and that their impact on sensing is heightened by the CNT network's proximity to percolation. First, we use a biased conducting AFM tip to gate a CNT-FET at the nanoscale and demonstrate that the strongest device response occurs when gating at metallic-semiconducting junctions. Second, we resolve the target sensitivity of an aptasensor as a function of tube density and show heightened sensitivity at densities close to the percolation threshold. We find the strongest sensing response where the 1% of metallic tubes generate a high density of metallic-semiconducting junctions but cannot form a percolated metallic path across the network. These findings highlight the critical role of metallic tubes in CNT-FET biosensor devices and demonstrate that network composition is an important variable to boost the performance of electronic biosensors.
(Copyright © 2018 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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