KB0042: Identifying BioNex GSC Generations

There are two generations of MindWare product versions that measure Galvanic Skin Conductance (GSC) and they have different measurement ranges. This article is intended to help identify your product version and choose appropriate gains. This only applies to the BioNex Impedance Cardiograph Module (50-371100-00) and BioNex 3-Channel Bio & GSC Module (50-371101-00). The BioNex Impedance Cardiograph 2 Module (50-371135-00) has fixed GSC gain with a scaling of 10μS/V.

First generation modules were produced prior to 2014 and have a larger measurement range but higher minimum conductance. Second generation modules were produced starting in 2014 and have a smaller range but resolve lower GSC values. First generation circuits can be upgraded to second generation circuits for a nominal fee. Contact sales@mindwaretech.com for details.

To identify your module generation:

  1. Open BioLab and configure the GSC channel for a gain of 10
  2. Attach a harness and leads
  3. Start previewing the GSC channel
  4. Short together the two GSC leads by holding the metal part of the snap ends together (a paperclip or other conductive object may be necessary to make contact.)
    1. If the raw signal level reads about 4V, it is a 1st Generation GSC circuit
    2. If the raw signal level reads about 1V, it is a 2nd Generation GSC circuit

First Generation

Gain Range Scaling
500 2 – 2250 μS 500 μS/V
250 2 – 1125 μS 250 μS/V
100 2 – 450 μS 100 μS/V
50 2 – 225 μS 50 μS/V
25 2 – 113 μS 25 μS/V
10* 2 – 45 μS 10 μS/V
5 2 – 23 μS 5 μS/V

Second Generation

Gain Range Scaling
500 0.2 – 450 μS 500 μS/V
250 0.2 – 225 μS 250 μS/V
100 0.2 – 90 μS 100 μS/V
50* 0.2 – 45 μS 50 μS/V
25 0.2 – 22.5 μS 25 μS/V
10 0.2 – 9 μS 10 μS/V
5 0.2 – 4.5 μS 5 μS/V

*Recommended starting gain to encompass a majority of the normal human GSC range. Lower gain number have a smaller range but produce higher resolution results and can be used with subjects having lower peak GSC readings. Some subjects may approach the upper range limit and a higher gain value should be used to prevent exceeding the limits of the amplifier.

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