Grove GSR Sensor doesn’t sense resistance on the arm

Hi Guys,

I have bought GSR-sensors:

That work perfectly fine on the fingers. However, for a DIY project, I would like to measure the resistance on my arm. Thus, I've just connected two electrodes that are distanced 5mm on a wearable textile to the Grove PCB. The PCB cannot sense any variation in the resistance of my arm. I am sure it's due to the high resistance (>50MOhm), as measured with a multimeter.

Is there a way to measure such high resistances? I believe with over 50MOhm, there's simply no way anymore since probably 100MOhm is the absolute maximum.

Thank you!

Sure there are ways, but you can't use the best way - to increase the applied voltage. That is what some measuring devices "meggers" do. Obviously, you can't use high voltages because of the shock hazard. I suspect the electrodes are just not making good contact with the skin. The skin resistance of your arm is not that different than your fingers. Skin resistance is highly variable and depends a lot on how much moisture is around the electrode/skin junction. That is why, for ECG/EEG, they use tape and/or paste on the electrodes, to provide a reliable connection.