When did the Jedi start using devices to measure Force sensitivity?

Is it during the Ruusan era?

the russian era

For serious though. The electronical device called Force Detector was first used by Palpatine actually, then there were lots of them, one of them was used by Luke when he was beginning to build his New Jedi Order. Given the crystals fueling Force Detector came from Mimban, and Mimban arose to the galactic eyes only in the time of RotE and them the Rebellion era, I highly doubt it happened before that.

However, if you mean the blood tests, they were already around at Bane's times.

Originally posted by JKBart
For serious though. The electronical device called Force Detector was first used by Palpatine actually, then there were lots of them, one of them was used by Luke when he was beginning to build his New Jedi Order. Given the crystals fueling Force Detector came from Mimban, and Mimban arose to the galactic eyes only in the time of RotE and them the Rebellion era, I highly doubt it happened before that.

However, if you mean the blood tests, they were already around at Bane's times.

Confirming my theory, then.