Detection of long-lived species in plasma-activated water, based on digital colorimetry

To fit a specific application, a cheap and effective manner of measurement of chemistries in plasma-activated water (PAW) is in demand. We propose a digital colorimetry-based method of quantifying the long-lived species in PAW using only smartphones and specialized software. Pin-plate discharge and surface microdischarge were used to generate the PAWs. H(2)O(2)and NO(2)(-)were selected as representatives for the test. Various color parameters were extracted from images of a solution consisting of testing species and colorimetric reagent. Specialized curve-fitting strategies were developed during data processing. The results were consistent with those measured by UV-Vis spectrometry, but they provided better performance and simplified operation. Additionally, the proposed PAW generator design can be integrated with the detecting module based on this method.