Not 100% but the only thing that would make sense is Dr Royal Raymon Rife's work and research. If you really want to see some amazingly simple technology research this guy.
Uses Frequency technology to kill virus seamlessly. Its pretty incredible.
Dr. Raymond Rife: Cured Cancer in 1934, Then He was Killed
https://cloudmind.info/dr-raymond-rife-cured-cancer-in-1934-then-he-was-killed/