Highlights

“Nong Fai Chai Gen 3”, A Robotic UV-C COVID-19 Disinfection Lamp Is Now Operational to Keep Frontline Personnel 100% Confident and Safe


The Faculties of Medicine and Engineering, Chulalongkorn University, Smile Robotics and King Mongkut’s University of Technology North Bangkok (KMUTNB) have jointly developed “Nong Fai Chai, Generation 3” — a UV-C disinfection lamp that can kill 99.99% of the COVID-19 virus and other germs within 3 minutes, now ready to assist front-line staff.


During the COVID-19 pandemic, health workers have been at the forefront of high-risk groups as they are the ones who need to be in contact with infected people daily over long periods of time.  The COVID-19 virus can float in the air for some time. It can also live on various surfaces for many hours, or even days depending on environmental factors, so disinfecting the workplace for frontline personnel is of utmost importance.

For this reason, the team has jointly developed a “Robocovid UV-C disinfection lamp” or “Nong Fai Chai” that is able to disinfect the area and create a safe space for medical personnel.  This is the third generation of the lamp after the previous two generations that the team developed during the early waves of the outbreaks.  The recently unveiled “Nong Faichai Gen 3” is guaranteed to work faster with more disinfection power.

Prof. Somrat Charuluxananan, M.D., Department of Anesthesiology, Faculty of Medicine Chulalongkorn University
Prof. Somrat Charuluxananan, M.D.

The birth of “Nong Fai Chai”

Prof. Somrat Charuluxananan, M.D., Department of Anesthesiology, Faculty of Medicine Chulalongkorn University who initiated the project explained the motivation behind the innovation.

“During the first wave of the COVID-19 outbreaks, all levels of the hospital staff were at risk. So, if there was a way to prevent infection and ensure safety for the staff, we would not hesitate to pursue it.  It was very important to create a sterile work environment, like cleaning after use. We thought about how to make sure the cleaning crews were safe from the disease.”

A team from the Faculty of Medicine, led by Prof. Dr. Somrat, therefore requested cooperation from Assoc. Prof. Dr. Anongnat Somwangthanaroj, Associate Dean, Faculty of Engineering, and Assoc. Prof. Dr. Proadpran Punyabukkana, Department of Environmental Engineering, Faculty of Engineering, Chula to develop a disinfection device for the operating theatre that are safe for the staff.  Prof. Dr. Boonrat Lohwongwatana, Department of Metallurgical and Material Engineering, and Dr. Jenyuk Lohwacharin, Department of Environmental Engineering, Faculty of Engineering, were also part of the development team.

Dr. Jenyuk Lohwacharin
Dr. Jenyuk Lohwacharin

“The challenge of this innovation was to create a device that could disinfect the room when no one was there. This was preliminary disinfection for the safety of the cleaning staff who would come in to clean and disinfect, wipe and scrub the surface, walls, and equipment again with various disinfectants afterward,” said Dr. Jenyuk.

Why “UV-C lamp”?

Dr. Jenyuk explained that in engineering, UV-C radiation has the wavelength range of 200 – 280 nm, known as the germicidal range, a very effective disinfectant against bacteria, viruses, and fungi.

“The strength of UV-C rays that hit the surface is important for disinfection, comparable to the concentration of chemicals used to kill germs. The stronger the radiation, the less time it takes,” explained Dr. Jenyuk.

“Radiation concentration (fluence) is measured in joules/sq. cm.  Several studies indicate that the UV-C light intensity of at least 1.2 Joules/sq.cm. or 1,200 mJ/sq.cm. for 10 minutes per spot can effectively kill COVID-19.  We used this number as the basis for calculation for our robotic UV-C lamps.  The angle of exposure also needed to be calculated to maintain the right concentration to kill germs.

All three generations of “Nong Fai Chai” UV-C disinfection lamp are the brainchild of Mr. Adisak Duangkaew, a robot engineer, and two-times World Rescue Robot Champion from KMUTNB, and Smile Robotics. The robot is designed with vertical UV-C tubes and is of the same height as human beings.  They have wheels for mobility and can be remotely controlled.

“In the first generation, the UV-C lights were installed at right angles, so the light projection onto the floor or the area that the robot passes through was not at the optimal level.  The light could be projected to about a 3-meters radius or approximately 20-25 square meters.  So, in Gen 2, we tilted the UV-C lights to increase the coverage, both in terms of the area and fluence,” said Dr. Jenyuk.

Nong Fai Chai, Generation 3, a UV-C disinfection lamp
Nong Fai Chai Gen 3

“Nong Fai Chai Gen 3” removes the germs effectively, quickly, and omnidirectional

COVID-19 virus can be killed easily. The tests by the Faculty of Engineering which are consistent with the findings of the Faculty of Medicine and the research done abroad found that the concentration of radiation used with the first two flashlights can effectively kill 99.99 – 99.999 % or more.

Nong Fai Chai Gen 3 can perform even better than that. The development team has improved the third-generation lamp to be more effective in dispersing UV-C radiation omnidirectionally and helps to shorten the disinfection time to only 3 minutes per spot while being small and compact, easy to use, move and store.  It can also be controlled via the Internet of Things (IoT) or a 2G smartphone network both on Android and iOS.

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“Tests of disinfection efficiency were carried out at different distances: at ground level, at 50 cm above ground, and on various surfaces, including glass, plastic, metal.  Other pathogens that are tougher to eliminate than COVID-19 were also introduced to the tests as surrogate endpoints. it was found that the Nong Fai Chai robotic lamp was highly effective in disinfection. Other hospitals that have been using the lamps also gave an ‘excellent’ nod,” Prof. Dr.

Somrat added on the performance tests of Nong Fai Chai Gen 3 that the Department of Anesthesiology carried out in collaboration with the Bacteriology Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University.

Nong Fai Chai, Generation 3, a UV-C disinfection lamp
Nong Fai Chai Gen 3

All models of the lamps are now operational, and the next generation is poised to be developed.

At present, “Nong Fai Chai 3” is providing disinfection and cleaning services to many hospitals across the country, such as in the delivery room of the Obstetrics and Gynecology Department, Chulalongkorn Hospital.  There are plans to expand and deliver Nong Fai Chai to other hospitals as well.

Dr. Jenyuk concluded about the future of ‘Nong Fai Chai the next generation’, that “the type of UV-C lamp that we use today may emit ozone gas.  Although ozone can help kill germs and can dissipate by itself.  However, there are concerns about ozone residue affecting the surface of equipment, so we’re looking at other types of lamps with the best energy efficiency that might be more environmentally friendly, even though the ones we are using are already very efficient and environmentally friendly to a certain extent.”


Those interested in supporting the team’s research and development or want to obtain “Nong Fai Chai” robotic lamp for hospitals or field hospitals can contact the Department of Anesthesiology, Faculty of Medicine, Chulalongkorn University Telephone +66-2256-4000 ext. 81513.

Chula’s encouragement and support for research is excellent for teachers, students, and the public.

Associate Professor Dr. Suchana Chavanich Faculty of Science, Chulalongkorn University