A breath of fresh tech鈥攃arbon nanotube sensors sniff out gases with unprecedented precision

Lisa Lock
scientific editor

Robert Egan
associate editor

A team of researchers at IMDEA Nanociencia institute and Universit脿 Cattolica del Sacro Cuore has unveiled a new class of gas sensors based on MINT-functionalized carbon nanotubes, offering unprecedented precision in detecting and distinguishing volatile organic compounds.
This "electronic nose" is made of a tailored array of chemiresistors to sense gases like ammonia, nitrogen dioxide or acetone vapors at room temperature, paving the way for low-power environmental monitors and wearable breath diagnostics. The findings are in the Journal of the American Chemical Society.
Single-walled carbon nanotubes are ideal materials for sensing due to their high surface area, but their extreme sensitivity has long come with a downside: poor selectivity. To address this, researchers have "dressed" carbon nanotubes with ring molecules to improve their ability to discriminate between chemical compounds.
These derivatives of carbon nanotubes, known as Mechanically Interlocked Carbon Nanotubes (MINTs), provide a way to introduce chemical functionalities onto carbon nanotubes without altering their intrinsic structure.
The MINT-based chemiresistors responded significantly better to target gases鈥攊ncluding NH鈧�, EtOH, IPA, benzene, NO鈧�, acetone, and NaClO鈥攖han unmodified carbon nanotubes, even at low concentrations (10鈥�200 ppm). Researchers proved their detection limit, being below tens of parts-per-billion (ppb).
Assembled into an array, these sensors behave like an artificial olfactory system, able to selectively identify specific analytes despite the presence of potential interferences. For instance, ammonia was successfully distinguished from a range of other vapors. One optimized sensor layer even showed up to 10脳 higher sensitivity and faster response times, simply by reducing the film thickness.
The research constitutes a proof-of-concept e-nose, that not only demonstrates the power of MINT-based sensors for complex gas detection but also highlights their customizability. With synthetic control over the structure of the interlocked molecules, researchers can finely tune the sensor's properties, opening a new frontier in the design of smart, selective, and scalable electronic noses.
More information: Michele Galvani et al, Efficient Implementation of MINT-Based Chemiresistor Arrays for Artificial Olfaction, Journal of the American Chemical Society (2025).
Journal information: Journal of the American Chemical Society
Provided by IMDEA Nanociencia