Operation Manual____________________________________________________________Accessories
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9-2
For maximum transmission of acoustic energy into a vessel, use a cavitation-resistant fluid
such as a water-glycol mixture, pure ethylene or propylene glycol. The sonication intensity
will be greatly increased, in proportion to the glycol concentration.
OPERATION
Most laboratory grade plastic or borosilicate glass vessels which will fit into the cup are
suitable for sonication. Polystyrene and polycarbonate are the best transmitters of acoustic
energy. Polypropylene and polyethylene are too soft and may be ineffective. Glassware
must be free of any scratches and fully annealed or it may over stress and crack.
Ultrasonic energy is radiated directly upward through the base of the vessel while
transmission through the side is negligible. For this reason, flat bottomed vessels are best
and round bottomed are next best. Vessels should have thin, uniform bases, without any
heavy edges or centers. Conical tubes should be tilted to expose maximum sample area to
the horn. Samples should be wide and shallow, rather than high and narrow.
Maintain a small clearance around the vessel to allow adequate coolant flow. Suspend
vessels at least ” to ¼” (3 to 6 mm) above the face of the horn.
Energy in the cup can be determined easily by the pattern of sonication (cavitation bubbles
or micro-streaming) in the coolant. At low levels, the bubbles will usually appear as a dome
of bubbles capping the coolant exit in the face of the horn. As the amplitude of the horn
(output control knob setting) is raised, the bubble pattern will lift and become vertical
diaphanous streams in the center of the cup, sometimes forming a spider-like pattern.
OUTPUT SETTING PARAMETERS
When working with small samples there is a tendency to turn the Amplitude Control Knob
too high. Doing so causes the ultrasonic energy to go around the vessel, not through it.
The chart below is a good guide on selecting a power setting according to liquid sample
volume. However, all samples differ and my require a slightly higher power setting
according to solid content and viscosity.
Sample Volume
Power Setting
100
μ
l - 500
μ
l
0 - 1
500
μ
l - 2 ml
1 - 2
2 ml - 5 ml
2 - 4
5 ml - 20 ml
4 - 5
20 ml - 50 ml
5 - 7
50 ml - 200 ml
7 - 8
