A study of the autofluorescence of parylene materials for μTAS applications

Parylene-C has been widely used as a biocompatible material for microfluidics and micro total analysis system (μTAS) applications in recent decades. However, its autofluorescence can be a major obstacle for parylene-C based devices used in applications requiring sensitive fluorescence detection. In this paper, Parylene-C was compared with other commonly used polymer and plastic materials in μTAS devices for their autofluorescence. We also report here an in-depth study of the behaviors and mechanisms of the autofluorescence of parylene-C, as well as several other commercialized members in the parylene family, including parylene-D, parylene-N and parylene-HT, using epifluorescence microscopy, fluorimeter and infrared spectroscopy. Strong autofluorescence was induced in parylene-C during short-wavelength excitation ( i.e. UV excitation). Variation of autofluorescence intensity of parylene-C film was found to be related to both dehydrogenation and photo-oxidation. Moreover, the influence of microfabrication process on parylene-C autofluorescence was also evaluated. Parylene-HT, which exhibits low initial autofluorescence, decreasing autofluorescence behavior under UV excitation and higher UV stability, can be a promising alternative for μTAS applications with fluorescence detection. We report a study of the autofluorescence behaviors and mechanisms of parylene materials (parylene-C, -D, -N, -HT) for μTAS applications. Given its better autofluorescence performance, parylene-HT can be a useful alternative to the widely used parylene-C if low autofluorescence is required.