Pheromonic sensor
From Memory Alpha, the free Star Trek reference.
The pheromonic sensor is a type of sensor commonly used on explosive devices. They are triggered when a particular individual or species comes within range. Flaxian assassins are known to favor pheromonic sensors, so Elim Garak used a pheromonic sensor to trigger a bomb in his shop in 2371, thus implicating the Flaxian assassin Retaya. (DS9: "Improbable Cause")
Ferengi locator bombs use pheromonic sensors to lock onto their target. (DS9: "The Nagus")
