Hi,
I bought a Grove GSR Sensor and I want to interface it with Arduino Uno to measure stress level. I was expecting the GSR Sensor to get the output based on skin conductance or resistance. But i found from another forum that GSR gives only analog voltage reading.
How can I interpret this analog voltage output to skin conductance (microsiemens) or skin resistance?
Any help on this is appreciated. Thankyou.
Take a look at the schematics of your sensor breakout. The skin sensor builds a voltage divider together with R6. The resulting voltage is then amplified and put to the output pin. You can influence the output value using the onboard potentiometer. Usually the actual resistance in Ω is not needed, just the changes over time are of interest. If you need the Ω value, you probably have to calibrate yourself using a multimeter.
I suspect that will only ever give you a qualitative measure, or a sort of pseudo-quantity, in that under stressless conditions you'll get "these" values and under stress you'll get "these other" values.
In all the movies they ask the subject his name and age and stuff to get a set of normal readings.
Thankyou all for the response.
"They're just questions, Leon. In answer to your query, they're written down for me. It's a test, designed to provoke an emotional response... Shall we continue?"
You can easily convert the resistance value (R_skin) into the signal of your interest using voltage divider (half-bridge) circuit analysis.
V_out=R_skin/(R_ref + R_skin) x V_in