[Zurück]

H. Böhm, L.G. Briarty, K.C. Lowe, J.B. Power, E. Benes, M.R. Davey:
"Application of a novel h-shaped ultrasonic particle separator under microgravity conditions";
in: "Proc. Forum Acusticum 2002", A. Calvo-Manzano, A. Pérez-López, J.S. Santiago (Hrg.); Sociedad Española de Acústica, Madrid, Sevilla/Spain, 2002, (eingeladen), ISBN: 84-87985-06-8, Paper-Nr. PHA-01010, 6 S.

The application is described of a novel, h-shaped ultrasonic resonator for the separation of biological
particulates. The effectiveness of the h-shaped resonator has been demonstrated using
suspensions of the cyanobacterium, Spirulina platensis. Separation of Spirulina at cleared flow
rates from 14 - 58 L/d, as assessed by remote video recording, was evaluated under both
microgravity (£ 0.05 g) and terrestrial gravity conditions. In comparison with previous systems,
the h-shaped resonator provided a more homogeneous acoustic field intensity, flow characteristics
and overall separation efficiency ( s = 1, ratio of concentration in cleared phase to input),
monitored with a turbidity sensor. The new separation concept also works in the absence of
gravity forces, although gravity forces influenced overall efficiency. During a typical microgravity
period of ca. 22 s, achieved during the 29th ESA Parabolic Flight Campaign, s was 0.96 ± 0.01
at a flow rate of 14 L/d, compared to terrestrial gravity conditions, whereas with increased flow
rates (38 L/d), s reduced to 0.71 ± 0.01. Overall, these results demonstrate that, for optimum
resonator performance under the relatively short microgravity period utilised in this study, flow
rates of ca. 14 L/d are preferable. These data provide a baseline for exploiting non-invasive,
compact, ultrasonic separation systems for manipulating biological particulates under microgravity
conditions.
Keywords: acoustic separation; cell trapping; microgravity, separation efficiency; Spirulina
platensis; ultrasonic h-resonator