title: Microfilters by laser processing of bio-polymers.
abstract: Thin films of bio-polymers, such as polymethylmetacrylate, polytetrafluoroethylene, polyethylene-terephthalate and polyimide, are efficiently etched in air by UV laser pulses. A different sharp laser fluence threshold for significant etching is measured for each polymer. The thresholds are correlated to the chemical structure and to the wavelength-dependent absorption coefficient of the irradiated polymer. The polymers, having low absorption coefficients, show thresholds of the order of some J/cm2, about one magnitude higher than polymers having high absorption coefficients. Measurements on the polymer etching rates, in terms of removed molecules per eV at the used 347 nm wavelength, and a discussion on the laser-polymer interaction are presented. An interesting application of the laser ablation process to bio-polymers, concerning the ability to realize microfilters for the bio-medical field by irradiating the polymer surface through a perforated metal mask, is discussed.
authors.affiliation: Dipartimento di Fisica, Università di Messina Ctr, Papardo, S. Agata (ME), Italy.
authors.forename: L
authors.initials: L
authors.lastname: Torrisi
mesh_terms: D000042:Absorption; D005069:Evaluation Studies as Topic; D005374:Filtration / Q000295:instrumentation*; D007834:Lasers; D008768:Methylmethacrylates / Q000737:chemistry*; D008904:Miniaturization; D009757:Nylons / Q000737:chemistry*; D010777:Photochemistry; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013499:Surface Properties; D014466:Ultraviolet Rays
chemical_list: D008768:Methylmethacrylates; D009757:Nylons; D011093:Polyethylene Terephthalates; D011138:Polytetrafluoroethylene