Abstract
Colorimetric gas sensors are gaining increasing attention as simple, low-cost, and rapid tools for on-site detection. In this work, a flexible colorimetric sensor for hydrogen sulfide (H2S) detection was developed based on electrospun polylactic acid (PLA) nanofibers functionalized with bromocresol green (BCG). The PLA/BCG nanofibers exhibited a uniform morphology with an average diameter of approximately 250 nm, and the incorporation of the dye did not significantly alter the structural or chemical properties of the polymer matrix. The sensor showed a distinct, concentration-dependent response to sulfide species, first validated in aqueous Na2S solutions and subsequently confirmed in gas-phase experiments. Under the tested conditions, the sensor was able to visually detect H2S at concentrations as low as 100 ppb, exhibiting a rapid response within approximately 1.5 s. The membrane also demonstrated good long-term stability, retaining its initial color for at least five months under ambient laboratory conditions. The proposed system combines flexibility, rapid response, and long-term stability, making it a promising platform for wearable applications and environmental monitoring.
