Ultra-Sensitive Mercury Sensor Based on Thin Film Transistor using Flavin Self-Assembly on Monochiral Carbon Nanotubes

Abstract

Achieving ultra-sensitive mercury detection requires precise molecular design and seamless integration with electronic sensing systems. Here, we show that a monochiral single-walled carbon nanotube (SWCNT) thin-film transistor (TFT) sensor, helically wrapped with flavin molecules, achieves remarkable sensitivity to mercury ions down to 1 pM. To accomplish this, we adopted several complementary strategies. Monochiral SWCNTs were first isolated using N-dodecyl flavin (FC12) in a mixed solvent system, ensuring high structural uniformity. The resulting FC12-sorted SWCNT complexes were then efficiently assembled onto TFT devices through mixed self-assembled monolayers, maximizing device sensitivity. In addition, a distinctive coordination-based sensing motif, combined with PEGylation of the gold electrodes, suppressed nonspecific interactions and enhanced selectivity. The finalized molecular recognition-driven TFT sensor detects mercury ions through the formation of a flavin–Hg–flavin coordination triad across a concentration range of 1–100 pM, a response not observed with other metal ions. By tightly integrating molecular recognition with electronic transduction, this platform enables highly precise and ultra-sensitive detection, offering strong potential for early identification of environmental contaminants and disease-associated biomarkers.