title: Characterization of multi-dye pressure-sensitive microbeads.
abstract: The response times of pressure-sensitive particles to passing shockwaves were measured to investigate their ability to accurately determine pressure changes in unsteady flows. The particles tested were loaded with novel pressure-sensitive dyes such as Pt (II) meso-tetra(pentafluorophenyl)porphine, Pt(II) octaethylporphine, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl))iridium III, and iridium(III) bis(4-phenylthieno[3,2-c] pyridinato-N,C2')acetylacetonate. For this work, porous silicon dioxide pressure-sensitive beads (PSBeads) were used. Two synthetic procedures were used to fabricate the particles. In the first, a one-step method loaded dyes during the synthesis of microbeads, in the second a two-step method synthesized the microbeads first, then loaded the dyes. The shock tube facility was used to measure the response times of microbeads to fast pressure jumps. The study involved testing multiple luminophors loaded in microbeads with various size distributions. Response times for the silica-based microbeads ranged between 26 μs and 462 μs (at 90% of the amplitude response), which are much faster than previously reported polystyrene-based microbead response times, which range from 507 μs to 1582 μs (at 90% of the amplitude response) [F. Kimura, M. Rodriguez, J. McCann, B. Carlson, D. Dabiri, G. Khalil, J. B. Callis, Y. Xia, and M. Gouterman, "Development and characterization of fast responding pressure sensitive microspheres," Rev. Sci. Instrum. 79, 074102 (2008)].
authors.affiliation: Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lacroix
authors.forename: Teddy
authors.initials: T
authors.lastname: Viraye-Chevalier
authors.forename: Guillaume
authors.initials: G
authors.lastname: Seiter
authors.forename: Jonathan
authors.initials: J
authors.lastname: Howard
authors.forename: Dana
authors.initials: D
authors.lastname: Dabiri
authors.forename: Gamal E
authors.initials: GE
authors.lastname: Khalil
authors.forename: Younan
authors.initials: Y
authors.lastname: Xia
authors.forename: Cun
authors.initials: C
authors.lastname: Zhu
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D008863:Microspheres; D011312:Pressure; D059629:Signal-To-Noise Ratio; D012822:Silicon Dioxide / Q000737:chemistry*; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D012822:Silicon Dioxide