Triphenyl methane dyes as sensor materials for solvent detection with surface‐acoustic‐wave devices

Highly‐colored phthalide carbenium ions (see figure) embedded in a matrix of phenols can form the basis of solventsensing devices able to detect a variety of solvents in concentrations down to a few ppm. Solvent absorption disturbs hydrogen bonding producing a less favorable environment for the cations, the changing concentration of which can be monitored using optical absorption, or SAW‐devices. magnified image