3Brain BioCAM X, User Manual

Page: 30 / 45

30
BioChip Calibration
In case you experience several electrodes with short or prolonged periods of time where no signal is
visible, you may suffer signal saturation problems. In this case, follow these steps before proceeding on
with recording data.
A typical example of a chip with saturating behavior is illustrated in the image below. On the left, the
MEA Viewer shows many deep blue colored pixels indicating not working channels while on the right
typical raw data traces with short periods of saturation (top-left, top-right and bottom-left) or even with
persistent saturation (bottom-right) are shown.
This behavior might be related to a wrong setting of the working point of the amplifiers that are integrat -
ed underneath the electrodes. In such case, follow the instructions below for a correct BioChip calibra-
tion; if the problem persists you can refer to the section “Electrodes with no-signal (saturation)” .
BrainWave features two functions to perform BioChip calibration: an automatic and a manual procedure.
The automatic calibration button is positioned in the Commands panel. To perform an automatic calibra-
tion you first need to start an acquisition (by clicking on the Play button) and then to click on the BioChip
Calibration button. The procedure will take from few tens of seconds up to roughly a minute, depending
on the BioChip conditions.
If automatic calibration is not satisfactory you can perform a manual calibration. To access this feature
you need the Chip Calibration panel (if not opened, go to BrainWave menu: Window > Recorder > Chip
Calibration). From the panel you can move the sliding bar to set a value for the amplifier bias that mini -
mizes the saturation of the electrodes. Normally, value in the range of 0 to -100 allows to achieve good
performances, but values out of this range might be needed too. Moving the bar toward higher nega-
tive values will eliminate saturation from those electrodes that oscillate between working condition to
saturation (i.e. blinking deep blue pixels in the MEA Viewer control). If you set a too high negative value,
some electrodes will start saturating permanently (i.e. fixed deep blue pixels in the MEA Viewer control).
For a correct setting start from values close to 0 and move the bar by small steps towards the left until
an optimal condition is found.
Automatic Chip Calibration Manual Chip Calibration