According to the directions issued by the World Health Organization (WHO), surgical masks are essential personal protective equipment (PPE) against Covid19 and other viruses. The protection provided by these masks highly depends not only on the efficiency of the filter media but also on the level of the leakage around the face/mask interface^1,2,3. The metal clip that most of the surgical masks provide aims at reducing this leakage at least on the upper level of the mask. However, after a while this clip may loosen and a gap appears letting non-filtered air enter inside the mask. This may result in another well-known problem that of glass fogging (steaming up glasses). Recently studies¹ imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency. In an effort to reduce particle leakage between the face and the mask, we introduce a clip of various sizes, that adapts well to the human nose following its curves. The curves are designed with Bézier lines and this has as a result both to isolate the mask better from the non-filtered air and make it comfortable while you are wearing it. The two plastic fasteners that hold the metal clip of the mask are designed in a way that does not crack easily while at the same time they grab the upper edge of the mask tightly. Important note: when you fit the mask to the clipper do not forget to fold the mask’s fabric at the upper edge of the mask.

How to select the right size?

Following a fully parametric design, we are able to provide sizes for this clip by moving three control points of the Bézier lines. The first point Y0 defines the height of the clip, while the points X1 and X2 define the opening of the clip (that is how much narrower or wider the clip will be). Selecting the right size is very easy. Just follow these three steps: 1st step: Print the most used* clip: clip_0_0.stl 2nd step: Select the clip_X_Y.stl with X > 0 for wider clip Select the clip_X_Y.stl with X < 0 for narrower clip 3nd step: Select the clip_X_Y.stl with Y > 0 for higher clip Select the clip_X_Y.stl with Y < 0 for lower clip

^* The size of this clip is used more often than the other sizes. ^1. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks, Abhiteja Konda, +5 authors, ACS Nano, 2020. ^2. An overview of filtration efficiency through the masks: Mechanisms of the aerosols penetration, A. Tcharkhtchi, +5 authors, Journal Bioactive Materials, Accepted August 2020. ^3. Filtration Performance of FDA-Cleared Surgical Masks, Samy Rengasamy, +3 authors, Journal of the International Society for Respiratory Protection, 2009.

Found 12 3D-models for “Facemask clips” across many websites

Surgical Mask Ear Saver mouse clip

DIY Fabric Face Mask Clip 2

T-Shaped Facemask clip

No-Sew FaceMask Clip

Fabric Face Mask Clips

3D Printed Magnet Ear Savers Parts Remix

face mask cap clip earsaver

Mask Visor Clip

Mask ear saver with quick release clips

Facemask Car Sun Visor Clip

Surgical mask clips

FFP2 Maskholder for Helmets (Simple)