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. 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.