A Surface Enhanced Raman Scattering (SERS) microdroplet detector for trace levels of crystal violet

We report on a microfluidic platform that integrates a winding microdroplet chip and a surface-enhanced Raman scattering (SERS) detection system for trace determination of crystal violet (CV). Colloidal silver was applied to generate SERS. Compared to the continuous flow microfluidic system, the microdroplet based detection described here effectively eliminates any memory effects. Effects of flow pattern, droplet size, surfactant, and position of detection were optimized. Under optimal conditions, there is a linear correlation between signal and the concentration of CV in the 10 nM to 800 nM range, with a correlation coefficient (R-2) of 0.9967. The limit of detection in water is 3.6 nM.