# Label-Free Detection of 2,4-Dinitrotoluene Using a Laser-Induced Graphene Based Chemiresistive Sensor

## TL;DR

A low-cost, flexible sensor made from laser-induced graphene can detect the explosive 2,4-dinitrotoluene with high selectivity and sensitivity.

## Contribution

A label-free, laser-induced graphene-based chemiresistive sensor is developed for selective and sensitive detection of 2,4-dinitrotoluene.

## Key findings

- The sensor achieved a detection limit of 3.79% (2.4 × 10–9 M) for 2,4-dinitrotoluene.
- The sensor showed strong selectivity against related compounds like nitrotoluene and ethanol.
- Laser-induced graphene films exhibited uniform conductivity and low defect density.

## Abstract

The rapid and sensitive detection of nitroaromatic explosives
is
of paramount importance for both security and environmental monitoring.
In this study, a label-free chemiresistive sensor based on laser-induced
graphene (LIG) was developed for the selective detection of 2,4-dinitrotoluene
(DNT). LIG films were directly fabricated on polyimide substrates
via a single-step laser writing process, resulting in porous and conductive
surfaces without additional modification. The structural, chemical,
and electrical properties of the fabricated materials were comprehensively
evaluated using scanning electron microscopy (SEM), X-ray diffraction
(XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy,
X-ray photoelectron spectroscopy (XPS). The electrical properties
were characterized by current–voltage (I–V) measurements using a Kelvin (pseudofour-point) configuration.
SEM revealed a porous morphology formed during laser scribing, while
XRD and Raman spectroscopy confirmed multilayer graphene (∼5
layers) with relatively low defect density. FTIR spectroscopy indicated
residual oxygen-containing functional groups, and XPS verified DNT
adsorption. The fabricated films exhibited a uniform electrical conductivity
of 1545 S/m. By employing these films, a chemiresistive sensor was
developed, which demonstrated a response toward DNT, achieving an
estimated detection limit (LOD) of 3.79%, corresponding to 2.4 ×
10–9 M. Strong selectivity was observed against
structurally related interferents such as nitrotoluene, toluene, and
ethanol. These results demonstrated that LIG-based flexible sensors
provide a low-cost, scalable, and selective platform for explosive
detection with promising applications in security and environmental
monitoring.