title: The autofluorescence of plastic materials and chips measured under laser irradiation.
abstract: Plastic materials have the potential to substitute for glass substrates used in microfluidic and microTAS systems adding flexibility in materials' choices. Optical quality plastic materials with a low autofluorescence are crucial for optimal detection by fluorescence and laser induced fluorescence techniques. This paper summarizes a series of optical investigations on commercially available plastic chip materials (PMMA, COC, PC, PDMS) and chips made from those materials. Intrinsic optical constants of plastic materials-refractive index for bulk materials-determined by spectroscopic ellipsometry and transmission spectroscopy in the visible range are presented. The laser-induced autofluorescence of materials and chips was assessed at four laser wavelengths, namely, 403, 488, 532 and 633 nm. Considerable bleaching of the autofluorescence was observed under continuous laser illumination. Overall, the longer wavelength laser excitation sources yielded less autofluorescence. PDMS exhibited the least autofluorescence and was comparable to BoroFloat glass. In all cases, chips exhibited slightly higher autofluorescence than the raw plastic materials from which they had been made.
authors.affiliation: Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH 45221, USA.
authors.forename: Aigars
authors.initials: A
authors.lastname: Piruska
authors.forename: Irena
authors.initials: I
authors.lastname: Nikcevic
authors.forename: Se Hwan
authors.initials: SH
authors.lastname: Lee
authors.forename: Chong
authors.initials: C
authors.lastname: Ahn
authors.forename: William R
authors.initials: WR
authors.lastname: Heineman
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Limbach
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Seliskar
mesh_terms: D019544:Equipment Failure Analysis; D007834:Lasers; D008422:Materials Testing / Q000379:methods*; D046210:Microfluidic Analytical Techniques; D010969:Plastics / Q000032:analysis* / Q000737:chemistry* / Q000528:radiation effects; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D010969:Plastics