Headstage Test Dongle; Gain And Noise Measurements - imec NEUROPIXELS 1.0 User Manual

functional and whether data integrity criteria are met. On probe-level, these tests verify the correct
programming of and data streaming from the probe ASIC thus assessing functionality and performance
of the electrodes and integrated electronics.

Headstage Test Dongle

The HST is a small test box (Figure 10) that plugs into the HS ZIF connector of a HS. Its purpose is to
help verify the functionality of a HS. This is useful when e.g. neural data seems corrupted or cannot be
recorded or when a probe cannot be programmed correctly anymore.
Disconnect your probe from the HS and insert the HST flex into the ZIF connector of your HS. Run the
HS tests which are enabled in the application software (Open Ephys, SpikeGLX). In case of failure, the
application provides more detailed information about the exact source of the failure (e.g. power supply,
serial data link, clock signal, reset signals, etc. LEDs on the HST indicate status and result of the HS tests.
We recommend to always repeat the HS test also with an un-used, good HS.

Gain and Noise Measurements

The functionality and performance of a probe can also be verified with a simple gain and/or noise
measurement in PBS solution. These measurements should be performed after loading the probe
configuration files into software.
Gain measurements must be performed using the external REF shorted to GND. This can be achieved
by soldering two wires to the respective pads on the probe flex and shorting them to a signal generator's
ground (Figure 36). If configured for a nominal gain of 1000 for both AP and LFP channels, a sinusoidal
test signal of e.g. 500 µV
the PBS using a Pt, stainless steel or Ag|AgCl counter electrode. The resulting mean gain should not
deviate >10% from the nominal value and at least 90% of the electrodes should have a gain within 5%
of the mean gain. The results can provide qualitative and quantitative information about electrodes
and/or channel performance.
Noise measurements should always be performed in a grounded Faraday cage. One can use either an
internal REF electrode or the external REF shorted to GND. The reference selection is done via the GUI.
The PBS solution must be grounded (Figure 36). During noise measurements, all internal REF electrodes
must be immersed in PBS to avoid unwanted noise pick-up and cross-coupling. When using the external
REF, the external REF electrode must be grounded via the REF and GND contact pads on the flex.
NEUROPIXELS 1.0 USER MANUAL V1.0.5
and 1.8 kHz or 100 Hz, for AP or LFP band, respectively, can be applied to
pp
Figure 36: Setup for gain measurements in PBS.
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