3 links have been added on this idea.
  1. Check out this fantastic concept of using water nanobots to kill airborne and surface-based bacteria and viruses.
    https://www.hsph.harvard.edu/nano/research/research-projects/killing-bacteria-and-viruses-with-engineered-water-nano-strucuture/

  2. Some hospitals are already using robots to kill bacteria and viruses.
    https://www.cbc.ca/news/canada/british-columbia/germ-fighting-robots-in-fraser-health-get-more-help-killing-hospital-bacteria-and-viruses-1.6562814