Create a micro or nanomelecular robotic device that can search, then open a path to the person within rubble or defense position.

Nanobots would seek out a person or persons then create a tunnel reinforced by the bots. The bots would move and assess the space, material, and distance to the person or body of interest. The devices if constructed on nanomelecular scale would be able to decompose various substances then draw in other bots as they move material like ants.