Optimization of Carbon Nanotube Percolation Networks for Broad Dynamic Range Detection of Permanganate in Water

Percolation networks of single-walled carbon nanotubes (SWCNTs) are widely used in chemiresistive sensors due to their tunable electronic properties, which control the sensitivity of the devices. This study explores the tunability of the electronic properties of SWCNT-based chemiresistive films by controlling the percolation network density. We demonstrate that simple spectroscopic measurements can ensure repeatability in the sensor fabrication process and that optimizing the percolation network can expand the useful detection range for the desired analyte. We show that percolation networks within three resistance ranges can be utilized to detect a disinfectant (permanganate), which has applications over a wide concentration range. Devices fabricated with the highest resistance (∼25 kΩ) were shown to detect lower range concentrations of permanganate (0.01–0.1 mg/L, limit of detection, LoD 0.0001 mg/L), medium resistance devices (∼15 kΩ) can detect midrange concentrations (0.2–1.6 mg/L, LoD 0.002 mg/L), and low-resistance devices (∼5 kΩ) can detect high-range concentrations (1– 8 mg/L, LoD 0.03 mg/L), depending on the specific application. SWCNT networks can also be further functionalized to enhance the sensitivity, selectivity, and stability of the devices. This study highlights the potential of SWCNT percolation networks for customizable chemiresistive sensing in environmental monitoring and industrial applications.