title: Development of catheters with low fiber background signals for Raman spectroscopic diagnosis applications.
abstract: Utilization of optical-fiber catheters can turn the Raman spectroscopy system into a powerful remote biomedical diagnostic probe. An in vivo (a qualitative and a quantitative) biochemical diagnosis of biotissues is possible by developing the Raman-fiber probes with a good flexibility and less background signals generated in the probes themselves. Considering the isotropic nature of Raman scattering, the amount of Raman signal guided through the fiber is expected to depend on the numerical aperture (NA) of the fiber. To study the dependence for catheter probes experimentally, various flexible probes (with small diameter fibers) with different combinations of numerical apertures and with different assembling materials (biocompatible) have been developed. The catheter probes have been characterized by collecting the near infrared excited Raman scattered light from cholesterol powder. The results demonstrate that the catheters with a combination of lower NA (0.12) fibers used for laser excitation and relatively higher NA (0.22) fibers for Raman signal collection will have lower background signals generated in the probes. Furthermore, the catheters with a black Teflon tubing cover and black epoxy resin adhesives were found to give better results.
authors.affiliation: Instituto de Pesquisas e Desenvolvimento, Universidade do Vale do Paraíba, Urbanova, São José dos Campos, São Paulo, Brazil.
authors.forename: C J
authors.initials: CJ
authors.lastname: de Lima
authors.forename: S
authors.initials: S
authors.lastname: Sathaiah
authors.forename: L
authors.initials: L
authors.lastname: Silveira
authors.forename: R A
authors.initials: RA
authors.lastname: Zângaro
authors.forename: M T
authors.initials: MT
authors.lastname: Pacheco
mesh_terms: D000269:Adhesives; D016477:Artifacts; D001672:Biocompatible Materials; D002404:Catheterization / Q000295:instrumentation*; D002784:Cholesterol / Q000737:chemistry; D003952:Diagnostic Imaging / Q000295:instrumentation; D004853:Epoxy Resins; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D055100:Optical Fibers; D018583:Pliability; D011138:Polytetrafluoroethylene; D011208:Powders; D012542:Scattering, Radiation; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D013499:Surface Properties
chemical_list: D000269:Adhesives; D001672:Biocompatible Materials; D004853:Epoxy Resins; D011208:Powders; D011138:Polytetrafluoroethylene; D002784:Cholesterol