Morphology-Evolving Colorimetric Thin-Film Sensor for Visual Detection of Hypochlorous Acid
Year: 2026
Type: article
Abstract: Hypochlorous acid (HClO) is widely used as a low-cost and effective disinfectant; however, its instability under heat and light necessitates simple and reliable monitoring methods. Herein, we report a morphology-evolving thin-film colorimetric sensor that enables intuitive visual detection of HClO through simultaneous color and pattern transitions. The sensor integrates two polymer films with distinct charge-state response behaviors, patterned into X-shaped and circular geometries on a single substrate. Upon exposure to HClO, chlorine-induced modification of amide and amine groups alters the surface charge states, thereby switching the adsorption preference for anionic and cationic dyes. This mechanism results in a pronounced transformation from a blue X-shaped motif to a red circular pattern, enabling direct visual discrimination of HClO concentrations. Quantitative analysis of RGB values and diffuse-reflectance UV–vis spectra confirmed semi-quantitative detection in the sub-millimolar to low millimolar range. The sensor further demonstrated practical applicability by tracking photodecomposition of a commercial disinfectant. This work demonstrates pattern-coupled colorimetric sensing as a straightforward, user-friendly approach for HClO monitoring.
Source: Sensors
DOI: 10.3390/s26072082
Authors: Yasumasa Kanekiyo, Takumi Kato, Emi Sakai
Institution: Kitami Institute of Technology
Language: English
Subfield: Bioengineering
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7141013953