“Germ-Zapping” Robot Aims to Make Hospitals Cleaner and Safer

December 23, 2016 by Ami Vyas

Through the emission of short, intense pulses of light, the Xenex robot is able to sanitize large spaces in a small amount of time - a function quite useful for trying to eliminate the risk of hospital acquired infections like C.diff and MRSA.

The Xenex robot, which looks like something straight out of a science fiction movie, produces UV rays that usually stay in the cosmos. It's changing the way hospitals handle infectious diseases by using UV light to sanitize the small organisms that cause us the biggest problems.

Hospital-Acquired Infections (HAIs)

Hospital-acquired infections or healthcare-associated infections (HAIs), are highly prevalent in the United States, with about 722,000 patients contracting one annually according to the Center for Disease Control and Prevention. This amounts to about one out of every 25 admitted patients. The fatality rate for HAIs is over 10%, making it one of the most serious problems modern hospitals face.

HAIs are transferred in various ways, depending on the type of infection. Many times, they are the result of bacteria that has developed a resistance to treatment with antibiotics.

The Xenex robot is an example of how medicine and engineering intersect to improve healthcare. This device is capable of using UV light to sanitize healthcare facilities with extraordinary thoroughness.


The Xenex robot sanitizing a hospital room. Image courtesy of Xenex.

Better Technology, Better Hospitals

Xenex began as a startup founded in 2008 by epidemiologists Dr. Mark Stibich and Dr. Julie Stachowiak. Their Xenex LightStrike Germ-Zapping Robot uses Full Spectrum Pulsed Xenon UV (PPX-UV) light to kill infection-carrying pathogens in hospital rooms.

Compared to the older technology of mercury UV disinfection, the Xenon bulbs used in the Xenex robot sweep across the entire UV-C spectrum, eliminating a wider range of infectious organisms, with the newest version of the robot targeting six of the most problematic pathogens for HAIs. It can also target the pathogens causing Ebola, Anthrax, HIV, and many other communicable diseases. The high-intensity light is sent in brief pulses out of the machine, which would be placed in the center of an empty hospital room for a total of only five minutes.

The light pulses aim to destroy the cells of the bacteria, viruses, and fungi that cause HAIs. Because UV-C rays from the sun are usually deflected by the ozone layer, earthly organisms have not developed a resistance to them. In methods similar to but more intense than antibiotic treatments, the population of pathogens is destroyed by irreversible destruction of their DNA so that they cannot replicate. The cell walls are also irreparably damaged, causing likely cell death.

In the Xenex robot, this is accomplished through four processes:

  • Photohydration – the UV light attracts water molecules into the DNA, which disrupts the replication process
  • Photosplitting – the “backbone” of the strands of DNA within the bacteria are broken
  • Photodimerization – the “rungs of the ladder” in a strand of DNA are fused together to give the improper code to any future replications. This is the only process that Mercury UV Disinfection is capable of.
  • Photocrosslinking – damages the cell wall by preventing the creation of new proteins.

These events effectively destroy the DNA replication and repair mechanisms within the cells. Different pathogens are susceptible to different wavelengths of UV-C light, which is why the broad spectrum provided by Xenon bulbs is so effective.

Representation of the four processes the Xenex robot employs to destroy bacterial DNA. Image courtesy of Xenex.

Sensors and UV-C

The Xenex robot is much smarter and easier to work with than its predecessors. In the newest edition, the engineers have incorporated many premium parts that help the machine be its best. The disinfection cycle is a much shorter and more predictable five minutes compared to the varying 25 to 45-minute cycle that Mercury bulbs require. The unit runs on wall power and can clean up to 64 hospital rooms in one day without overheating. The Xenon bulbs, themselves, are also non-toxic, unlike the Mercury bulbs used in previous technologies.

The robot is equipped with Wi-Fi and cellular connectivity to provide real-time monitoring of data and diagnostics. The GUI loaded in the machine is simple and allows for custom report generation. Perhaps the most interesting engineering feature added is a safety measure. The UV-C light emitted from the Xenex is more harmful to humans than UV-A or UV-B. However, this light cannot travel through walls or glass, so it is only harmful if a human is in the room while the machine is in operation.

The newest Xenex robot incorporates sensors to ensure that a human is not around. These include heat readings and movement sensors to automatically turn the machine off if someone is in the room. The robot also comes equipped with sensor-loaded caution signs to warn anyone about to enter the room and interact with the machine to stop the light pulses if a person is about to enter. Read the details of the door proximity sensor patents here.


Motion sensors placed in front of doors detect when someone enters a room being sanitized. Image courtesy of Xenex.


The Xenex company has over 12 patents regarding the robot, including frequency and duration of pulses, xenon gas mixtures, and other features.

The Xenex robot has brought forth the useful, almost futuristic technology of Xenon lamps while incorporating features which make it extremely easy and safe to use. It’s definitely here to stay – unlike the bacteria it’s after.