100 nm scale low-noise sensors based on aligned carbon nanotube networks: overcoming thefundamental limitation of network-based sensors

Abstract

Nanoscale sensors based on single-walled carbon nanotube (SWNT) networks have beenconsidered impractical due to several fundamental limitations such as a poor sensitivityand small signal-to-noise ratio. Herein, we present a strategy to overcome thesefundamental problems and build highly-sensitive low-noise nanoscale sensors simply bycontrolling the structure of the SWNT networks. In this strategy, we prepared nanoscalewidth channels based on aligned SWNT networks using a directed assembly strategy.Significantly, the aligned network-based sensors with narrower channels exhibited evenbetter signal-to-noise ratio than those with wider channels, which is opposite toconventional random network-based sensors. As a proof of concept, we demonstrated100 nm scale low-noise sensors to detect mercury ions with the detection limit of∼1 pM, which is superior to any state-of-the-art portable detection system and is below theallowable limit of mercury ions in drinking water set by most government environmentalprotection agencies. This is the first demonstration of 100 nm scale low-noise sensors basedon SWNT networks. Considering the increased interests in high-density sensor arrays forhealthcare and environmental protection, our strategy should have a significant impact onvarious industrial applications.