Neurotechnology Research Systems
Stimulator 2.0
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5.6
Compliance voltage and stimulation failure
It is important to monitor the electrode voltage during stimulation to verify that the desired
stimulation pattern was successfully applied to the electrode. There is a maximum voltage that the
stimulator can output called the compliance voltage. Once the voltage on the electrode reaches the
compliance voltage, the stimulator can no longer drive current into the electrode. The successful
delivery of a given stimulation protocol will depend on the amplitude of the current pulse, the
duration of the pulse, the stimulator compliance limit, and the properties of the electrode.
To see this effect, first stop the ongoing stimulation by pressing the “Edit” button for channel 1:
This stops the stimulation and returns the controls for channel to edit mode.
Next, increase the first phase width and second phase width parameters to 1000 µs:
Then “Load” and “Start” channel 1:
Observe the current monitor output on the oscilloscope:
Although the amplitude of the first phase still looks okay the duration appears to be too short and
the duration of the inter-phase period appears to be too long.
~600
µs
1000 µs
~400
µs
+250 mV @ I
MON
= +100 µA @ electrode
–250 mV @ I
MON
= –100 µA @ electrode
