title: Integrated hydrogenated amorphous Si photodiode detector for microfluidic bioanalytical devices.
abstract: Hydrogenated amorphous silicon (a-Si:H) PIN photodiodes have been developed and characterized as fluorescence detectors for microfluidic analysis devices. A discrete a-Si:H photodiode is first fabricated on a glass substrate and used to detect fluorescent dye standards using conventional confocal microscopy. In this format, the limit of detection for fluorescein flowing in a 50-microm deep channel is 680 pM (S/N = 3). A hybrid integrated detection system consisting of a half-ball lens, a ZnS/YF3 multilayer optical interference filter with a pinhole, and an annular a-Si:H photodiode is also developed that allows the laser excitation to pass up through the central aperture in the detector. Using this integrated detection device, the limit of detection for fluorescein is 17 nM, and DNA fragment sizing and chiral analysis of glutamic acid are successfully performed. The a-Si:H detector exhibits high sensitivity at the emission wavelengths of commonly used fluorescent dyes and is readily microfabricated and integrated at low cost making it ideal for portable microfluidic bioanalyzers and emerging large scale integrated microfluidic technologies.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kamei
authors.forename: Brian M
authors.initials: BM
authors.lastname: Paegel
authors.forename: James R
authors.initials: JR
authors.lastname: Scherer
authors.forename: Alison M
authors.initials: AM
authors.lastname: Skelley
authors.forename: Robert A
authors.initials: RA
authors.lastname: Street
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mathies
mesh_terms: D010584:Bacteriophage phi X 174 / Q000737:chemistry; D001583:Benzoxazoles / Q000032:analysis / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D003505:Cyclodextrins / Q000737:chemistry; D004247:DNA / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D019075:Electrophoresis, Capillary / Q000295:instrumentation*; D019793:Fluorescein / Q000032:analysis; D005456:Fluorescent Dyes / Q000032:analysis / Q000737:chemistry; D005971:Glutamates / Q000032:analysis / Q000737:chemistry; D006865:Hydrogenation; D044085:Microfluidics / Q000295:instrumentation*; D018613:Microscopy, Confocal; D011804:Quinolines / Q000032:analysis / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D013237:Stereoisomerism; D047408:gamma-Cyclodextrins
chemical_list: D001583:Benzoxazoles; D003505:Cyclodextrins; D005456:Fluorescent Dyes; D005971:Glutamates; D011804:Quinolines; D047408:gamma-Cyclodextrins; C097015:oxazole yellow; D002482:Cellulose; C002283:hydroxyethylcellulose; D004247:DNA; D015252:Deoxyribonucleases, Type II Site-Specific; C024403:GGCC-specific type II deoxyribonucleases; C023792:gamma-cyclodextrin; D019793:Fluorescein; D012825:Silicon