Killing Viruses with Heat: Can It Be Done?
With the current public health crisis, the use of medical wearables is gaining quite a bit of traction. From wearable devices that can detect symptoms early on, to self-cleaning masks, inventors and consumers alike are looking for any way to stay healthy and slow the spread of COVID-19. At the start of the pandemic, the LOOMIA team got thinking about how heat could play a role in killing the virus. However, we were skeptical given recent doubts about Summer weather and its ability (or lack thereof) to produce any significant decrease in cases. Upon doing further research, we have become a bit more optimistic of the potential for direct heat, in the form of reusable PPE, to eliminate virulent strains. While none of these claims have been proven, and we are certainly a long way from proving out this concept in full; we would like you to hear us out.
Can Heat Kill Viruses?
Image: Center for Disease Control and Prevention (CDC)
For a while now, it has been known that high temperatures can have profound effects on the structure of bacteria. Heat sensitivity is regained during spore germination, and temperatures of 50 C (122 F) to 100 C (212 F) are needed to inactivate bacterial growth. This inactivation of bacteria is also dependent on the amount of time the heat is applied to the contaminated surface for, and how direct that contact is. If one were to wear say, heated gloves, they could potentially kill viruses with each surface they touch.
The Scientists Say...
According to the World Health Organization (WHO), Escherichia coli (E. coli) is killed at temperatures of 70 C (158 F) or higher. Where’s the proof of this claim? Well, two scientists from Stanford Medicine have provided it. Dr. Amy Price and Dr. Larry Chu wanted to test whether face masks could be safely disinfected through use of heat. This study was conducted in response to the shortages of PPE facing healthcare workers across the United States. To preface, this study does not advocate for people to disinfect masks for reuse by heat treatment in home ovens. This is emergent research, and the disinfection methods described in this report are not approved by the National Institute for Occupational Safety and Health (NIOSH).
Three disinfection methods were used, one of which was oven heat. An N95 mask made from static-charged cotton, and one made from melt blown fabric were tested. In the melt blown fabric, there was a 96.6% filtration efficiency after heat at 70 C (158 F) was applied in the oven for 30 minutes. This produced 99% E.coli disinfection. As for the static charged cotton, there was 70% filtration efficiency after the same temperature and duration was applied. This also produced 99% E.coli disinfection.
Now, what if you were to test the efficacy of this method with the latest coronavirus strain(s)? In a 2003 study, the stability of SARS Coronavirus when encountered with direct heat was tested. It was found that the virus was non-infectious after 56 C (132 F) for 90 minutes, 67 C (152 F) for 60 minutes, and 75 C (167 F) for 30 minutes. This shows that heat at these temperatures is effective at killing the virus. Keep in mind, this was a completely different strain than the current one. The strain used in this test was CoV-P9, and the current strain is COVID-19. So, this study only gives us a glimpse into what is possible.
What Does This Mean?
For one, this is all promising information. Most heating solutions for smart garments and wearable devices can heat to at least 140 F. As a reference, LOOMIA’s LEL can be programmed to heat from anywhere between 140 F (60 C) and 200 F (93 C). With that being said, the temperature range necessary to potentially kill coronavirus (or any bacteria for that matter) on contact could potentially be met by most heating solutions on the market today.
While there are wearable devices with sensors being developed to detect symptoms of COVID-19, there are none on the market that utilize heat to stop and/or slow the spread. Such a device is still in the research phase, and it could be a while until we see them in stores. However, researchers in Israel have reportedly invented a reusable face mask that can kill the coronavirus with heat from a phone charger. This mask contains a USB port that connects to a power source, such as a cellphone charger, that heats a layer of carbon fibers in the mask up to 70 C (158 F). It’s an interesting discovery, but it is not clear if this is a scalable solution.
How This Tech Can Be Integrated
For starters, Our LEL (LOOMIA Electronic Layer) is an easy-to-integrate heating solution. Not to mention, the temperature range is much higher than that of the proposed charger solution. As mentioned previously, the LEL can be programmed to reach a max temperature of 200 F. An additional benefit to a heating solution like the LEL is its thin, flexible form factor that allows for a seamless integration into any textile-based product.
While access to PPE is certainly better than it was at the beginning of the pandemic, many hospitals and facilities are still facing shortages of proper protection; and experts are saying the shortages will continue a little while longer. Therefore, it is possible that reusable masks and gloves that kill viruses on contact could be needed very soon. The technology is out there, and all that is left to do is experiment.