Ultraviolet Germicidal Irradiation for Disinfecting N95 Masks

Need of UV Disinfection

A sudden rise in the demand for N95 masks as PPE (Personal Protective Equipment), has been widely recognized among the general public during this COVID-19 pandemic. This unexpected demand has resulted in a limited supply of equipment. The need of the hour suggests disinfecting and reusing disposable N95 Filtering Facepiece Respirators (FFRs).

In this context, Ultraviolet Germicidal Irradiation (UVGI) is considered an effective adjunct. Though it is not a stand-alone technology, this could be a method for respiratory disinfection as it has corroborated effectiveness in inactivating an extensive group of pathogens including coronavirus.

Germicidal UV typically engages mercury-based lamps operating at 254nm, the energy at which strongly absorbed by nucleic acids, resulting in damaging RNA and DNA molecules in pathogens preventing their further growth and function.

Moreover, the irradiation level of UVGI inactivating those pathogens does not hamper the fit and filtration characteristics of N95 FFRs. As per the literature, in the range of 0.5-950J/cm2, FFR fit performance is at 90-100% passing rate after 3 cycles depending on model whereas exposures as low as 2-5mJ/cm2 are capable of inactivating coronaviruses on surfaces. Thus, though proven to be an efficient method, UVGI could be used to effectively disinfect disposable respirators for reuse but the maximum number of disinfection cycles will depend on the respirator model and the UVGI dose required to inactivate the pathogen.

Simulating the performance of your UV System:

The design method of UV systems needs some questions to be answered before starting the design:

  • How much irradiance do we need to kill bacteria?
  • How many UV sources do we need?
  • What power should they have?
  • Where should we place them?

Simulation tools like ANSYS SPEOS help designers to efficiently answer these questions.

Besides, the ray-tracing capabilities of the tool also help in calculating accurately radiometric distribution in UVGI Devices with different surface reflectivities and lamp configurations.

ANSYS SPEOS Simulation to calculate Irradiance over the surface of N95 Mask

Apart from Radiometric studies, Structural Integrity of the respirators is one of the major concerns & studies show a noticeable decrease in structural integrity at lower doses. In conclusion, there are so many works of literature which suggests UVGI can be used for respiratory disinfection, though the maximum number of disinfection cycle will be limited by the respirator model and UVGI doses.

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Open the Door to Material Optimization


The world is evolving at a quantum speed with transforming technology. The human life cycle has enriched to tend towards advancement in every sector. Businesses have adopted the transformation & obtained the benefits of technology involved in their mainframe process to become multi-billion companies. Making the product a hero in every story, Engineering the product or designing a physical product demands focus on four major factors; Design, Analysis, Manufacturing, and Materials. Though the first three factors are digitally transformed, the materials field is still lagging. This article exclusively focuses on optimizing your right material choices.

Let’s start with an example of a company facing a similar conundrum.


Referring to the case of an OEM, that manufactures an industry renowned product.

Due to the stringent industry standards and to stay ahead of the competition, the company decided to optimize their existing product and its performance. Following the advancement, they relied on simulation results for quick feedback from different design iterations. Furthermore, parametric optimization yielded them even better results compared to the manual design iterations. Overall, they were able to achieve a 9% Reduction in Weight and a 5 % Increase in Efficiency through Design Optimization.

Much to the Team’s surprise, the product manager wasn’t satisfied with this result. Hence, he assembled his team to initiate an experiment with different material types. 

The broader idea of this activity was to understand how he could improve his product and cut down costs to the company, thereby naming this activity as Material optimization.

Optimized Product = Design Optimization + Material optimization

Following the superior’s directive, the team started dedicating their efforts to bring the best out of current results, in terms of cutting costs, reducing development time & raising standards of performance. Four of his team members heading the R & D were investigating the case study with different ideas as below. 

The first member tried to use the existing available material data with him to see if he can get the best possible combination;

The second member tried to use the materials preferred by his company to avoid supply chain issues;

The third member tried to reach out to suppliers/consultants for a piece of advice on material choices; and

The fourth member tried to browse on the internet for material data.

However, none of the above approaches answered the below questions

  1. Which material to choose?
  2. Is there a better material choice available?
  3. Is there a cheaper solution? 
  4. Is the chosen data, reliable?

This is where companies need a tool like, Granta Selector which does answer the above questions.

Granta Selector is a tool that can help optimize your material choices, which not only has material properties of metals, plastics, polymers, ceramics and various other classes of materials but also has features like search, plot and compare your choice of materials as shown in the pic.

Apart from the features mentioned above, Granta selector has:

  • FE export tool to export simulation ready material data to most of the FE platforms
  • synthesizer tool to estimate material and process cost 
  • Eco Audit tool to estimate the environmental impact of the selected material at the early stage of the design.

To use how to use above-mentioned tools, click here to understand how Tecumseh, a global leader of commercial refrigeration compressors used Granta Selector to reduce development time by three-fold and saved millions of euros of cost savings from making the right materials decisions.

please click here for more information on Material optimization.

Please feel free to connect with us at marketing@cadfem.in or +91-9849998435, for a quick Demo on this Product.

Author Bio:

Mr. Gokul Pulikallu, Technical Lead-South


Mr. Gokul Pulikallu has done his Bachelor of Technology  & he is carrying 9 years of experience in the field of structural Mechanics simulation and optimization. His main focus is Design Optimization & Material Optimization and helps customers adopt these technologies efficiently.

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