[Eeglablist] Negative Electrode Impedance?

[Nathan Sanders]

Hey Everyone,

In my continuing quest to get my system working, I discovered that many of
the electrodes have a negative impedance! Either I have solved the world's
energy problems or something is not working correctly.

Below is the output from BCI 2000's impedance check. We have a system of 4
16-channel g.USBamps. The funny thing is that 10 of the first 16 electrodes
are have varying negative impedance, but all the other 48 are consistently
at -10 kOhms. Weird huh.

Has anyone ever seen anything like this? I am not sure how to interpret
these results. We've been having trouble with tremendous amounts of EMI
which I suspect might be related to a bad ground or bad electrode(s), if
that helps.

Cheers,

Nathan

Amp 0 Ch  1 (UB-2011.07.15/01)   1 (FPz) :    -2.6 kOhm
Amp 0 Ch  2 (UB-2011.07.15/02)   2 (CPz) :    -6.2 kOhm
Amp 0 Ch  3 (UB-2011.07.15/03)   3 (Pz)  :     3.8 kOhm
Amp 0 Ch  4 (UB-2011.07.15/04)   4 (Oz)  :     4.6 kOhm
Amp 0 Ch  5 (UB-2011.07.15/05)   5 (POz) :     4.7 kOhm
Amp 0 Ch  6 (UB-2011.07.15/06)   6 (AFz) :     3.0 kOhm
Amp 0 Ch  7 (UB-2011.07.15/07)   7 (Fz)  :     4.1 kOhm
Amp 0 Ch  8 (UB-2011.07.15/08)   8 (FCz) :    10.0 kOhm
Amp 0 Ch  9 (UB-2011.07.15/09)   9 (Cz)  :    -4.6 kOhm
Amp 0 Ch 10 (UB-2011.07.15/10)  10 (FP1) :    -3.5 kOhm
Amp 0 Ch 11 (UB-2011.07.15/11)  11 (F1)  :    -5.6 kOhm
Amp 0 Ch 12 (UB-2011.07.15/12)  12 (AF3) :    -0.9 kOhm
Amp 0 Ch 13 (UB-2011.07.15/13)  13 (FC1) :    -6.4 kOhm
Amp 0 Ch 14 (UB-2011.07.15/14)  14 (C1)  :    -2.2 kOhm
Amp 0 Ch 15 (UB-2011.07.15/15)  15 (CP1) :    -3.3 kOhm
Amp 0 Ch 16 (UB-2011.07.15/16)  16 (P1)  :    -4.6 kOhm
Amp 1 Ch  1 (UB-2014.10.08/01)  17 (F3)  :    -9.7 kOhm
Amp 1 Ch  2 (UB-2014.10.08/02)  18 (CP3) :    -9.8 kOhm
Amp 1 Ch  3 (UB-2014.10.08/03)  19 (P3)  :    -9.8 kOhm
Amp 1 Ch  4 (UB-2014.10.08/04)  20 (FC3) :    -9.9 kOhm
Amp 1 Ch  5 (UB-2014.10.08/05)  21 (C3)  :    -9.8 kOhm
Amp 1 Ch  6 (UB-2014.10.08/06)  22 (PO3) :    -9.8 kOhm
Amp 1 Ch  7 (UB-2014.10.08/07)  23 (O1)  :    -9.8 kOhm
Amp 1 Ch  8 (UB-2014.10.08/08)  24 (P7)  :    -9.9 kOhm
Amp 1 Ch  9 (UB-2014.10.08/09)  25 (F5)  :    -9.8 kOhm
Amp 1 Ch 10 (UB-2014.10.08/10)  26 (AF7) :    -9.8 kOhm
Amp 1 Ch 11 (UB-2014.10.08/11)  27 (PO7) :    -9.9 kOhm
Amp 1 Ch 12 (UB-2014.10.08/12)  28 (FC5) :    -9.5 kOhm
Amp 1 Ch 13 (UB-2014.10.08/13)  29 (C5)  :    -9.5 kOhm
Amp 1 Ch 14 (UB-2014.10.08/14)  30 (F7)  :    -9.4 kOhm
Amp 1 Ch 15 (UB-2014.10.08/15)  31 (FT7) :    -9.3 kOhm
Amp 1 Ch 16 (UB-2014.10.08/16)  32 (TP9) :    -9.1 kOhm
Amp 2 Ch  1 (UB-2014.10.07/01)  33 (P5)  :    -9.7 kOhm
Amp 2 Ch  2 (UB-2014.10.07/02)  34 (CP5) :    -9.8 kOhm
Amp 2 Ch  3 (UB-2014.10.07/03)  35 (T7)  :    -9.8 kOhm
Amp 2 Ch  4 (UB-2014.10.07/04)  36 (TP7) :    -9.8 kOhm
Amp 2 Ch  5 (UB-2014.10.07/05)  37 (FP2) :    -9.8 kOhm
Amp 2 Ch  6 (UB-2014.10.07/06)  38 (AF4) :    -9.7 kOhm
Amp 2 Ch  7 (UB-2014.10.07/07)  39 (F4)  :    -9.7 kOhm
Amp 2 Ch  8 (UB-2014.10.07/08)  40 (FC4) :    -9.7 kOhm
Amp 2 Ch  9 (UB-2014.10.07/09)  41 (C4)  :    -9.7 kOhm
Amp 2 Ch 10 (UB-2014.10.07/10)  42 (CP4) :    -9.9 kOhm
Amp 2 Ch 11 (UB-2014.10.07/11)  43 (P4)  :    -9.9 kOhm
Amp 2 Ch 12 (UB-2014.10.07/12)  44 (FC2) :    -9.8 kOhm
Amp 2 Ch 13 (UB-2014.10.07/13)  45 (F2)  :    -9.3 kOhm
Amp 2 Ch 14 (UB-2014.10.07/14)  46 (C2)  :    -9.1 kOhm
Amp 2 Ch 15 (UB-2014.10.07/15)  47 (CP2) :    -9.5 kOhm
Amp 2 Ch 16 (UB-2014.10.07/16)  48 (O2)  :    -9.3 kOhm
Amp 3 Ch  1 (UB-2016.03.21/01)  49 (P2)  :    -9.7 kOhm
Amp 3 Ch  2 (UB-2016.03.21/02)  50 (PO4) :    -9.9 kOhm
Amp 3 Ch  3 (UB-2016.03.21/03)  51 (F6)  :    -9.8 kOhm
Amp 3 Ch  4 (UB-2016.03.21/04)  52 (FC6) :    -9.8 kOhm
Amp 3 Ch  5 (UB-2016.03.21/05)  53 (C6)  :    -9.8 kOhm
Amp 3 Ch  6 (UB-2016.03.21/06)  54 (CP6) :    -9.7 kOhm
Amp 3 Ch  7 (UB-2016.03.21/07)  55 (P6)  :    -9.8 kOhm
Amp 3 Ch  8 (UB-2016.03.21/08)  56 (TP8) :    -9.8 kOhm
Amp 3 Ch  9 (UB-2016.03.21/09)  57 (AF8) :    -9.8 kOhm
Amp 3 Ch 10 (UB-2016.03.21/10)  58 (F8)  :    -9.8 kOhm
Amp 3 Ch 11 (UB-2016.03.21/11)  59 (TP10):    -9.8 kOhm
Amp 3 Ch 12 (UB-2016.03.21/12)  60 (P8)  :    -9.9 kOhm
Amp 3 Ch 13 (UB-2016.03.21/13)  61 (FT10):    -9.5 kOhm
Amp 3 Ch 14 (UB-2016.03.21/14)  62 (PO8) :    -9.7 kOhm
Amp 3 Ch 15 (UB-2016.03.21/15)  63 (FT8) :    -9.7 kOhm
Amp 3 Ch 16 (UB-2016.03.21/16)  64 (T8)  :    -9.6 kOhm