Creating von Neumann machines would require a few technologies we don't have yet, including advanced artificial intelligence, miniaturization, and better propulsion systems.
The Purdue team has multiple patents on their technology and is working with government and industry players to miniaturize their tech into a tiny wearable circuit.
It has tested at least six nuclear warheads, and U.S. intelligence believes it has made progress on miniaturizing a nuclear warhead to mount on a missile.
The space program has pioneered the miniaturization of scientific equipment and helped engineers figure out how to land and maneuver a rover from millions of miles away.