Are Techies' Mines triggered by invisible units?
This is a pretty straightforward question: When an invisible hero (or other unit) gets within the trigger radius of a Land Mine or Stasis Trap placed by Goblin Techies, will the mine be triggered?
Yes Techie's Mine are triggered when an invisible enemy unit walks on them. You can for example use Lycan's wolves (lvl 4) to demine.
Yes. Anything that walk on those mines will make them blow up. In dota (TFT version) in techies games I used to grab either neutral creeps or pick heroes that could summon units and send them to patrol places where techies usually put their mines.
Notes: Always check the secret shop from the side lanes with a creep before going in first. Otherwise techies will have a good time.