Operation Manual_______________________________________________________________Applications
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12-1
12.
APPLICATIONS
PRINCIPLES OF ULTRASONICS
The generator (power supply) converts conventional 50/60 Hz AC line power to 20 kHz
electrical energy which is fed to the convertor where it is transformed to mechanical
vibration. The heart of the convertor is a piezoelectric crystal which, when subjected to an
alternating voltage, expands and contracts. The convertor vibrates in the longitudinal
direction and transmits this motion to the horn tip immersed in the liquid solution. Cavitation
results, in which microscopic vapor bubbles are formed momentarily and implode, causing
powerful shock waves to radiate throughout the sample from the tip face. Horns and
MICROTIP probes amplify the longitudinal vibration of the convertor; higher amplification (or
gain) results in more intense cavitational action and greater disruption. The larger the tip of
the probe, the larger the volume that can be processed but at a lesser intensity.
The convertor is tuned to vibrate at a fixed frequency of 20 kHz. All horns and MICROTIP
probes are resonant bodies, and are also tuned to vibrate at 20 kHz. Intense cavitation after
a prolonged period will cause the tip of the horns and MICROTIP probes to erode. Erosion
will cause a slight variation in frequency. It is important that the probe is retuned by
following the tuning procedure in 7-1 through 7-3.
The SONICATOR
®
Ultrasonic Liquid Processor will break down cells, bacteria, spores or
tissue. It can prepare an emulsion down to 1/100 of a micron, homogenize immiscible
liquids, polymerize some materials, de-polymerize others, and accelerate chemical
reactions. By virtue of this instrument, faster and more efficient extraction of serums, toxins,
enzymes, and viruses from organic sources is also made possible. Cavitation breaks down
cell structure rapidly, allowing the desired material to pass into the processing medium
before the cell contents undergo any substantial chemical change. It also does an excellent
job of degassing.
PROCESSING TISSUE
Whenever possible, the tissue should be diced very small to permit movement within the
liquid. Freezing followed by powdering could also be used, if this procedure is not
detrimental to the experiment.
Large samples should first be liquefied in a high speed mechanical blender for about 10
seconds. If sub-cellular particles are desired intact, the amplitude control should be set low
and the processing time increased.
Since the greatest concentration of energy is immediately below the probe, it is imperative
that the sample be kept as close to the tip as possible. Liquids are easily processed
because the free moving cells circulate repeatedly below the probe. Solid materials,
however, have a tendency to be repelled by the ultrasonic action. To alleviate this problem,
the vessel should be large enough to accommodate the probe, yet small enough to restrict
sample movement.
If the probe has to come in contact with a solid sample, use a standard ¾" (20mm) diameter
stainless steel centrifuge tube cut to 3" (70mm) length. Do NOT use a glass tube.
