WPI PicoPump PV830, Инструкция по эксплуатации

Страница: 18 / 28

14 World Precision Instruments
When pumping electrolytes, some indication of flow may be obtained by monitoring
the resistance or the voltage of the micropipette. If, for example, the micropipette
is filled with 3M KCl and the sample fluid is 0.1M KCl, a significant decrease in
resistance of the micropipette occurs when pressure is applied. This happens
because the resistance measured is determined primarily by the conductivity of
the solution at and within the tip. As pressure is applied the 0.1M KCl surrounding
the tip is replaced by the more highly conductive 3M KCl, decreasing the measured
resistance. Likewise, if vacuum is applied, the resistance increases as the less
conductive 0.1M KCl fills the tip.
NOTE : The above technique will not work with exterior and interior solutions of the
same concentration. However, a voltage change can be measured as a function of
the pressure applied. Working with tip sizes of 1–2µm, we have seen a change in
measured voltage of approximately 1mV for every 10 PSI of applied pressure.
Multibarrel Microinjection
For injection with multibarrel micropipette, the PolyFil multibarrel micropipette
coupling kit can be purchased from World Precision Instruments. This multibarrel
micropipette coupling kit allows easy and secure coupling of a multi-barrel
micropipette to a pressure source. Kits include a five-port manifold which allows use
of a single
PV830 to drive up to six micropipette barrels independently.
MAINTENANCE
The PicoPump has been designed to yield reliable performance. However particular
laboratory conditions may require occasional replacement of the pressure and
vacuum filters. Should this become necessary, return the instrument to the factory
for filter replacement.
Cleaning
Do not use alcohol, aromatic hydrocarbons or chlorinated solvents for cleaning.
They may adversely react with plastic materials used to manufacture the instrument.
The exterior of this instrument may be cleaned periodically to remove dust,
grease and other contamination. There is no need to clean the inside. Use a soft
cloth dampened with a mild solution of detergent and water. Do not use abrasive
cleaners.