“All-in-One” ultra-portable colorimetric sensor coupled with confinement effect for Hg2+ highly sensitive and instant detection

Due to the low sensitivity of traditional colorimetric sensors, complex and time-consuming signal amplification processes are often required in the actual detection process. In this work, with the aid of the porous nature of the gel matrix, a unique “All-in-One” ultra-portable colorimetric sensor has been constructed for highly sensitive and instant detection of low-abundance Hg2+ without signal amplification. Here, by dropping the prepared “Pill” sensor into the sample solution, the Hg2+ can specifically trigger the colorimetric reaction, so as to realize the on-site instant detection of Hg2+. Under the confinement effect, the porous structure of the gel matrix can serve as a preconcentrator to enrich the analyte, thus enhancing detection sensitivity of the sensor. Additionally, all colorimetric reactants are integrated into a small “Pill”, which greatly improves the portability of the sensor. Such an unusual sensor exhibits an outstanding linear response to the concentration in the range between 0.1 and 100 μM, and the detection limit is as low as 0.04 μM (S/N = 3). The as fabricated assay is sensitive, easy operation, and versatile. It has been successfully used for measuring Hg2+ in four different actual samples, demonstrating great promise for practical applications.