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Reference Section
Front Panel Display
When an electroporating pulse or pulse train is not active the Axoporator display
screen provides an update of the resistance measured at the tip of the micropipette.
This resistance is automatically updated. A ±300 mV peak-to-peak voltage is
delivered to the micropipette at frequency of 100 Hz. This voltage pulse and the
resulting current are used by the Axoporator to calculate the resistance. As the
micropipette touches the cell membrane the resistance increases and this is reflected
on the Axoporator display screen.
When an electroporating pulse or pulse train is active the Axoporator display screen
provides a measure of the current and the power of the pulse or pulse train. For
example, if a 10 V step is applied to a 10 M
Ω
micropipette, then one would expect
the resulting current to be 1 µA and power to be 10 µW. However, this does not
account for the duty cycle. If the pulse width is 300 ms and the pulse frequency is
1 Hz, then the duty cycle is 0.3 or 30%. The Axoporator automatically accounts for
the duty cycle. Thus, the current and power are displayed as 305 nA and 3.05 µW,
respectively. Note that a single pulse is considered to have duration of 1s. The
Axoporator will not follow a trigger that is faster than this. If you would like to
calculate the peak current of a single pulse, simply divide the current reading by the
duty cycle.
Axoporator 800A Theory and Operation, Copyright 2005 Axon Instruments / Molecular Devices, Corp.
