A smartphone-integrated paper-based colorimetric sensor array: Real-time detection and classification of flavonoids

Here, a smartphone-integrated paper-based colorimetric sensor array (PBCSA) was developed for distinguishing flavonoid-rich Citrus herbal products (FRCHPs): Citri reticulatae pericarpium, Aurantii fructus immaturus, Aurantii fructus, Citri grandis exocarpium, Citri reticulatae pericarpium viride, and Citri sarcodactylis fructus. Based on the strategy of indicator displacement assay induced by flavonoids, a 3 × 3 PBCSA with a hydrophobic barrier was constructed using inkjet printing technology. The PBCSA can accurately distinguished different species or concentrations flavonoids, and FRCHPs, demonstrating its broad applicability. After optimization with Genetic Algorithm, the Support Vector Machine (SVM) reduced the number of PBCSA sensor units from nine to five while maintaining an accuracy of 100.00 %, significantly improving the efficiency and accuracy of detection. Furthermore, the optimized SVM was integrated into a self-developed Quick Viewer app for real-time detection, greatly enhancing its practicability. This study not only presents a novel strategy for optimizing sensor arrays but also introduces a simple, economical, and real-time approach for analyzing FRCHPs.