Covid-19: "The face masks have a simple shape but feature high-quality materials"

When the coronavirus pandemic emerged, it caused a mask shortage in hospitals and doctor's offices. What was once an inexpensive product suddenly turned into a coveted commodity, which could only be purchased at a steep price if it was actually available in the first place. Mandatory face mask orders only exacerbated the problem in many countries. This gave rise to homemade face masks. It also prompted the Ulm University of Applied Sciences to study different types of textiles and materials to see whether they can provide a good fit and protection against the coronavirus when used in face masks. Their search landed the University on vacuum cleaner bag manufacturing. Professor Andreas Häger presented the stunning project to COMPAMED-tradefair.com.

Professor Häger, what is the goal of the Coronavirus Mask Project ("CORONA-Masken-Projekt")?

Andreas Häger: We launched the project when Germany faced an acute mask shortage amid the coronavirus pandemic. Back then, it was difficult to equip most healthcare workers with protective gear and face masks, let alone the average citizen. In response, many people created do-it-yourself masks that provided some relief and protection. We wanted to do our share by studying filter materials - especially dust filter materials - and examining whether they are suited for makeshift masks or even high-quality masks and face coverings. We started to source the materials and inspected dust filters (vacuum and dust collector bags, HEPA filters, etc.). These filters efficiently trap particles but don’t capture viruses. Meanwhile, FFP (filtering facepiece) masks (= protective masks certified by the European Union) also protect against aerosols.

We set up the relevant tests in our laboratory. This also included us connecting a probe device to an artificial lung to test masks in terms of respiratory resistance and leakage. We also teamed up with testing services and investigated aerosol penetration and breathability of various materials. Our research has shown that there are materials used in dust filtration that are structurally similar to FFP masks. We have filter materials that meet the requirements set for FFP1 or FFP2 masks as it pertains to air permeability and breathability. However, you cannot over-simplify things, meaning vacuum cleaner bags are not suitable for protection across the board.

What were your next steps after you had identified the right material?

Häger: During our research, we contacted the Löseke Company in Hildesheim. The Company specializes in dust filtration bags and flexible packaging products made of filtration paper and manufactured makeshift masks amid the coronavirus crisis. This marked the starting point for our collaboration. Together we have enhanced the product over the past few weeks, aiming to also make fitting masks for children. We established that the filter materials have the right structure, i.e. great stability and resistance and feature the same so-called melt blown filtering layer as FFP masks. This filter layer works by using electric charging of particles which helps to trap aerosolized particles. That’s why this material is well suited to produce makeshift masks. So far, the Company has made ca. 100,000 masks a day using an ultrasonic spot welding technique, which is the same method used for conventional disposable face masks. It all goes hand in hand: the masks are produced and we continuously optimize them at the same time. Having said that, the market will soon be saturated thanks to imports, prompting the production to gradually decrease again in the near future. We will still finalize the prototype for our optimized mask concept to prepare for a possible second wave of the coronavirus. Our concept is subsequently ready and available should this be the case.

Who received the masks you have made thus far?

Häger: Initially, the masks were picked up by pharmacies, but are now also available via several online stores.

Can the masks be made in all sizes with the ultrasonic spot welding process?

Häger: The face mask body is simple, making it easy to produce the masks in different sizes. We created a pediatric probe device in our laboratory using 3D printing for the children’s mask template. We scanned the heads of multiple children to accurately reflect the relevant facial proportions. The mask test setup allowed us to study the impact of a reduction in size on respiratory resistance and leak rates with positive results. The masks have a simple shape but feature high-quality materials. They can be easily tailored to fit everyone.