Need special microphone to record nighttime breathing

Hello
We have a prototype for a kids device that sits on a bedside table. We need to incorporate an affordable microphone that can pick up the sound of breathing at night. This will be difficult as there will be other noises in the room and the subject may be facing the other way. As long as the breathing is decipherable we can use algorithms to help isolate it from other sounds in the room. So we’re looking for someone with knowledge of working at very low volumes.