Bio-Rad MicroPulser™ Electroporator - Manual (Page 15)

3. Pulse Function
Pressing the "Pulse" button results in the capacitor charging to the set voltage; during this
time "PLS" is shown on the display LED. A tone will sound to indicate that the pulse has
been delivered. When multiple pulses are delivered by one of the built-in programs, "PLS" is
shown on the display LED during the entire time and a tone sounds each time a pulse is
delivered. To manually deliver multiple pulses, after the tone sounds from the first pulse,
press the pulse button again.
If a lower pitched tone sounds, accompanied by "Arc" being shown on the display LED,
the arc prevention and quenching (ARQ) system has been actuated and the pulse has been
terminated. This is usually an indication of attemped cuvette arc-over, but may also occur if
the sample resistance is too low. Since the energy delivered during such an ARQ event is
low, it is usually possible to pulse the sample again at parameters which will not result in an
arc and still produce acceptable results. However, it is not advisable to use a sample in which
two arc events have occurred.
4. Measurements
Pressing the "Measurements" button results in illumination of the "Actual kV" LED. This
indicates that the display LED shows the actual voltage delivered (in kV) during the last pulse.
If the instrument was just turned on and no pulse has been given, the display LED shows
"0.00". Pressing the "Measurements" button again results in illumination of the "Time ms"
LED. This indicates that the display LED shows the time constant (in msec) of the last pulse.
If the instrument was just turned on and no pulse has been given, the display LED shows
"0.00". Holding the "Measurements" button toggles the display LED between the Actual
voltage and the Time constant.
4.3 Electroporation Using The MicroPulser
1. Place the cell suspension in an electroporation cuvette and tap the liquid to the bottom of
the cuvette. Up to 0.4 ml (400 µl) of solution may be placed in the 0.2 cm cuvette, and up
to 80 µl may be placed in the 0.1 cm cuvette. Note that temperature may have a significant
influence on transformation frequency. Electroporation of some organisms, including
E. coli and S. cerevisiae, is more efficient in chilled cuvettes.
2. Insert the cuvette into the slide of the shocking chamber. Push the slide into the chamber
until the cuvette makes firm contact with the chamber electrodes.
3. To charge the capacitor and deliver a pulse, press the yellow "Pulse" button; the display
LED will show "PLS" until a tone sounds indicating that the pulse has been given. The
display LED will then show the program, the time constant, or the actual volts delivered,
depending on the LED selected.
4. Withdraw the slide from the chamber, remove the cuvette, and process the sample.
5. The time constant and the actual voltage delivered to the sample are shown on the display
LED by pressing the "Measurements" button. When the LED next to "Actual kV" is
illuminated, the voltage is displayed in kilovolts. The time constant can be displayed by
pressing the "Measurements" button again. The LED next to "Time ms" will be
illuminated; the time constant is displayed in milliseconds.
6. To turn the unit off press the power switch on the right rear panel. The sample chamber
may now be safely disconnected, if desired. Never remove the sample chamber cover
until the leads are disconnected.
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