GSR grove sensor is insensitive

[Wond3rboy]

Hi

I was trying to get this sensor working to measure the skin resistance with different excitations

**broken link removed**

The idea is relatively simple in that it measures the skin resistance which changes due to the sweat glands during different emotional states. Unfortunately, I haven't been able to detect a change in the states at all, for me it just keeps giving constant values when I wear it (the value does change from a no-wear state). The company seems to give no information on the pin connections either. They suggest the use of a shield which looks like just a connector board and thats why I havent bought it yet. I use the code listed on their wikipage but have left one wire called (TP4) unconnected since I don't know its purpose. I would be grateful if anybody can point me to better guides or if they have experience with this tell me if I am doing something wrong.

 

[Tony Stewart]

A $5 DMM can do the same thing with DC. However there is a galvanic voltage between the electrode metal and skin that varies with pressure. THese devices are rather poor sensors of intended emotional response and will be more affected by motion and pressure. The fingers may have poor sweat glands compared to areas of smooth skin. But then large areas will be more prone to galvanic pressure voltage. ( battery effect on electrodes)

I suppose they use suitable materials and even pressure to stability the readings.
What happens on maximum gain?

If touching the ground on the sensor input box does nothing to change the values, there is not much chance of improvement with a shield. You can try aluminimum foil while touching device input ground or nearby connected gnd.

My fingers resistance can vary from 5M to 50k, if wet, depending on contact area.

A more accurate method uses capacitance so that the DC galvo voltage ( battery effect) is avoided and conductance is a function of dielectric moisture content.

 

[Wond3rboy]

Thank you Tony for the insight. I will read more in to this.