How do I unlock disrupter mines?

[Citizen Cook]

Apparently I need the disrupter upgrade to get all of the Riddler trophies.

[MASTAN]

Upgrade disruptor in the WayneTech menu.

[NBOX21]

You also need to acquire previous upgrades before it to be able to get the Disruptor Mines upgrade. Check the skill tree to see how all the skills you want connect to each other so you know which ones to upgrade first to get the one you want.

[chipperMDW]

Whoever mentioned Iceberg Lounge must have thought you were asking about Arkham City; that was how you got that upgrade in that game, but it doesn't apply to Arkham Knight. In this game, it's just a normal skill in the skill tree.

[chipperMDW]

The "Disruptor - Sabotage Mine" upgrade is immediately down and to the right of "Disruptor - Sabotage Medic." It costs 3 upgrade points and requires the medic one to be purchased first.

Does that one have a lock symbol on it or something? I know that some upgrades are hidden until the game decides it makes sense to show them to you (like, maybe after you encounter a mine?), but I don't remember whether that's the case for that particular one.

Also, here's this video of someone showing that upgrade in the menu:

https://www.youtube.com/watch?v=BUUEePfTJkM

[chipperMDW]

What point are you at in the main story?

[BroSamaBinswagn]

in the wayne tech menu

[Citizen Cook]

Case solved!
For anyone reading in the future, the gadget upgrade unlocks automatically during the course of the story.
You don’t need to do anything particularly special. Just make sure you get “Disrupter Medic” first which is adjacent to it.