Life signs

From Memory Alpha, the free Star Trek reference.

You may be looking for the Star Trek: Voyager episode "Lifesigns".

Life signs are a collection of signals given off by lifeforms that indicate that they are currently alive, or functional. Upon approaching another starship or a planet for which they have limited intelligence, starships usually perform a scan for life signs. This information becomes part of the bridge crew's determination as to whether to board the ship, send a landing party, or carry out any other action.

Dr. Juliana Tainer was a Soong-type android that was designed to give off Human life signs. (TNG: "Inheritance")