UVC LED sterilization simulation experience sharing

- Nov 11, 2019-

When evaluating the sterilization effect of UVC-LED, how accurate is the accuracy of calculating the sterilization rate using simulations such as optics and fluids? Is it necessary to have a professional analog analyst for the team that is ready to enter? How is the sterilization rate calculation model established?


This is the question that the author recently discussed with several friends in the industry. During the discussion, everyone started from the beginning of each word to reach a consensus, and the author gradually got a clear answer. Maybe everyone has the same question in mind. Let's start sharing this time immediately. It is also hoped that we can throw a brick and attract jade.


Qualitative analysis is more practical


UVC-LED applications use the invisible light of the naked eye to kill invisible microorganisms. We need to indirectly study the process with tools. After decades of development of UVC lamps, various manufacturers have already summarized a set of practical simulation methods to guide product design. What level of UVC-LED can currently be achieved?


It is well known that the kill rate of microorganisms is related to the amount of UV received, which in turn is related to the intensity and duration of the radiation. The bactericidal effect is a comprehensive result of biosensitivity, optics, and fluid. In the simulation, if one of them has a deviation, the final result will be distorted.


The accuracy of optical simulation has been fully verified in the white LED industry, and various simulation tools are quite mature. Fluid simulation tools are widely used in the design of automobiles, ships, airplanes and even aerospace tools, and can be guaranteed with proper credibility. The optical and fluid coupling algorithm has also been used in the design of traditional UVC lamp sterilization products, so a more accurate UV dose can be obtained by simulation.


The main error comes from the basic data test.


The UV inactivation dose table for different microorganisms can be found in the professional literature. This dose is for traditional UVC lamps with a wavelength of 254 nm. Due to the different sensitivity of microorganisms to UVC light of different wavelengths, the traditional dosage form is not applicable. UVC-LED at a wavelength of 265-280 nm.


Taking E. coli as an example, the UV dose required to achieve a 99% killing rate using a UVC lamp is 6.6 mJ/cm2, and the UVC-LED is more efficient, achieving a killing rate of 99.99%. The UV doses given by the peers were approximately 3 mJ/cm 2 and 5 mJ/cm 2 , respectively.


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At present, no authoritative organization has released a sterilization dose meter for UVC-LED, and a few capable manufacturers can use the data themselves. Due to the differences in test methods and equipment, the data obtained is not the same. Suppose I know the UV dose of the product. Which data should I refer to to calculate the sterilization rate? Or do I need to be accurate on my own?


In summary, at this stage, a relatively accurate UV dose can be obtained through simulation, but the sterilization rate cannot be accurately estimated by the UV dose (except for some industry giants). At present, for most manufacturers, it is a more realistic solution to guide product design through simulation and qualitative.