Cardiff - UltraSound Levitation
Facilities are available to examine volumes ranging from a few µl to 1.01. The frequency range over which standing wave fields can be generated here is from 20 KHx to 10 MHz.
Microscopic studies of particle manipulation and aggregation. Microscopic studies are carried out with low megahertz frequency sanding waves where particle image velocitormery (PIV) and image analysis techniques provide information on microparticle and fluid behaviour in small volumes. This system can be found on through the Cardiff University School of Bioscience site at www.cardiff.ac.uk/biosi/
A USSW chamber is shown on the microscope stage of the picture above. Particle dynamics and aggregation, internally developed acoustic microstreaming and / or externally applied through-flow can be recorded and then analysed by particle image velocimetry.
Gravity independent ultrasonic standing wave force-field filter for particle filtration
A particle suspension flows between a plane transducer and reflector that are separated by one half wavelength. The left hand side schematic in the picture below shows particles concentrating in the nodal plane as they flow through the sound field. Clarified suspending phase is then drawn away from a side port downstream from the transducer. The lower photographic detail shows yeast suspension flowing in the absence of sound, while the upper ‘sound on’ detail shows cell concentration on axis and clarifying medium being drawn off through two downstream peripheral exit ports.
The facility consists of a computer controlled frequency synthesiser controlling a variety of power amplifiers and applying known voltages at scan-selected frequencies to the driving ultrasonic transducer. The system can be free standing as when used for non-sedimentation based (gravity independent) particle filtration and concentration or on a microscope stage for video recording of particle or fluid motion, study of particle aggregation or of droplet coalescence.
Last update: 23 January 2012