The manipulation of yeast cells and latex particles of diameters 1.3, 12 and in aqueous suspension in 1 and 3 MHz ultrasonic standing waves has been examined and compared in microgravity (0 g), 1 g and 1.8 g. The experiments were carried out during the 23rd ESA parabolic flight campaign. The suspended particles concentrated to form bands at half wavelength separation in the axial direction of a vertical tubular sample holder with a Bessel pressure amplitude distribution profile. At 1 g small ( latex) particles formed bands but these broke up within a few seconds. In contrast throughout 0 g bands of these particles formed and remained stable. The transition from 0 to 1.8 g during flight induced streaming which broke up the bands of latex. Bands formed with yeast cells were more stable at 1 g but, during transitions from 0 to 1.8 g, some bands broke up. Bands of the larger (12 and ) particles were stable at 0, 1 and 1.8 g and during all transitions between the fields. Thermal gradient convective flow rather than acoustic streaming was identified as the main source of flow in the sample holder at 1 g. The absence of thermal streaming at 0 g allowed manipulation of smaller particles in that situation. A frequency ramping technique appropriate for removal of particles from suspension in 1 g had a better performance in 0 g.

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A review of life sciences research in space, and the experimental infrastructure available or proposed for future development is presented. The monitoring of a wide range of chemical parameters is required in contrasting experimental configurations, ranging from autonomous experimental modules in sounding rockets, to bioregenerative life support systems on manned planetary bases. Microsystem technologies (MST) are proposed as a solution to the development of integrated chemical analysis systems which will meet both the diverse requirements for chemical monitoring systems, and the constraints of size and power imposed on instrument design by deployment on space missions. It is proposed that these technologies will transform the data yield from experiments, and expand the scope for more creative experimental protocol. The use of MST is illustrated with design concepts for cell microincubators, and a chemical analysis facility. The review concludes that the application to space life science research provides a challenging and unique opportunity for the development of demonstrator prototype microsystems.

The use of ultrasonic technologies to trap and filter desired particulates from a suspending media has been well documented to date. Recent advancements in microsystems and micro-fluidic technology have enabled the design of a miniaturised ultrasonic particle separation unit. The automated microsystem enables contact-less microprocessing operations to be conducted on small volumes of fluid suspensions in remote environments. Furthermore, the protocol for particle separation is simplified and reduces the need for operator handling.The microfabricated ultrasonic separator sub-system is combined with micro-fluidic components (valves, pumps, flow sensors) manifold systems and surface mount interface electronics to monitor and control the system's function. The operational function of the system utilises two reservoirs; (i) a pre-process reservoir containing crude sample extract, and (ii) a second reservoir holding wash media. During operation, a crude sample is channelled into the membrane-less filter system and manipulated by ultrasonic sound waves. Wash media is subsequently pumped into the filter, replacing or diluting the support media of the original sample. The sample is then removed, when desired, into a post-processing reservoir. The system has been developed for space micro-gravity operations and other configurations are applicable to other terrestrial processing applications.