title: An image cytometer based on angular spatial frequency processing and its validation for rapid detection and quantification of waterborne microorganisms.
abstract: We introduce a new image cytometer design for the detection of very small particulates and demonstrate its capability in water analysis. The device is a compact microscope composed of off-the-shelf components, such as a light emitting diode (LED) source, a complementary metal-oxide-semiconductor (CMOS) image sensor, and a specific combination of optical lenses that allow, through an appropriate software, Fourier transform processing of the sample volume. Waterborne microorganisms, such as Escherichia coli (E. coli), Legionella pneumophila (L. pneumophila) and phytoplankton, are detected by interrogating the volume sample either in a fluorescent or label-free mode, i.e. with or without fluorescein isothiocyanate (FITC) molecules attached to the micro-organisms, respectively. We achieve a sensitivity of 50 cells per ml, which can be further increased to 0.2 cells per ml by pre-concentrating an initial sample volume of 500 ml with an ad hoc fluidic system. We also prove the capability of the proposed image cytometer of differentiating microbiological populations by size with a resolution of 3 μm and operating in real contaminated water.
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. valerio.pruneri@icfo.es.
authors.forename: J M
authors.initials: JM
authors.lastname: Pérez
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. valerio.pruneri@icfo.es.
authors.forename: M
authors.initials: M
authors.lastname: Jofre
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. valerio.pruneri@icfo.es.
authors.forename: P
authors.initials: P
authors.lastname: Martínez
authors.affiliation: LABAQUA, S.A., c) Del Dracma, 16-18, 0314, Alicante, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Yáñez
authors.affiliation: LABAQUA, S.A., c) Del Dracma, 16-18, 0314, Alicante, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Catalan
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain. valerio.pruneri@icfo.es and ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Pruneri
mesh_terms: D004867:Equipment Design; D004926:Escherichia coli / Q000302:isolation & purification*; D016650:Fluorescein-5-isothiocyanate / Q000032:analysis; D005456:Fluorescent Dyes / Q000032:analysis; D019044:Image Cytometry / Q000191:economics / Q000295:instrumentation*; D016952:Legionella pneumophila / Q000302:isolation & purification*; D008853:Microscopy / Q000295:instrumentation; D012666:Semiconductors; D014871:Water Microbiology
chemical_list: D005456:Fluorescent Dyes; D016650:Fluorescein-5-isothiocyanate