Custom-made 3D-printed Face Masks In Case Of Pandemic Crisis Situations With A Lack Of Commercially Available FFP2/3 Masks

A custom-made 3D protective face mask was developed, consisting of two reusable 3D-printed components (a face mask and a filter membrane support) and two disposable components (a head fixation band and a filter membrane).

Facial image acquisition

3D facial scanning was performed using a smartphone (iPhone X; Apple Inc., Cupertino, CA, USA; https://www.apple.com) and the Bellus3D FaceApp (Bellus3D, Campbell, CA, USA; https://www.bellus3d.com), which was downloaded from the App Store. In order to prevent potential contamination of the smartphone, it was held by the person who performed the 3D facial scanning instead of the person who was being scanned. The individual face scan was then exported in high-definition (HD) OBJ file format and forwarded by secured e-mail to 3D Infinity (3D Infinity, Maldegem, Belgium; https://3Dinfinity.be) for 3D modelling and individual design of a custom-made 3D virtual face mask.

3D modelling and design of the reusable individualized face mask

Using a 3D modelling process with computer-aided design (CAD) software (SolidWorks; Dassault Systèmes SolidWorks Corp., Waltham, MA, USA; https://discover.solidworks.com), the STL virtual templates of the two reusable components of the 3D individualized face mask were designed by the CAD designer at 3D Infinity: (1) 3D face mask, and (2) filter membrane support. The connection between the two components was designed as a screw fixation type in order to allow ideal tightening after application of the filter membrane (Fig. 1). After downloading the OBJ file of the individual face scan, a Boolean calculation was performed by the CAD designer between the STL file of the individual face scan and the 3D face mask virtual template using Netfabb additive manufacturing software (Autodesk, San Rafael, CA, USA; https://autodesk.com) in order to obtain an accurate best-fit of the individual 3D face mask on its corresponding facial mask (Fig. 2).

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Fig. 1. Custom-made individualized 3D-printed protective face mask: (a) reusable 3D-printed face mask and (b) filter membrane support; (c) polypropylene (PP) non-woven melt-blown particle filter and (d) 3D image of the prototype.

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Fig. 2. Clinical two-thirds right facial profile views of a sterilization nurse (WS), providing an overview and comparison of the fit of a custom-made 3D-printed face mask with commercially available masks: (a) a disposable surgical face mask (BARRIER Medical face mask; Mölnlycke Health Care, Göteborg, Sweden); (b) a disposable FFP2 face mask (KN95 respirator mask; CTT Co., Ltd, Guangdong, China); (c) a disposable FFP3 face mask (FFP3 NR D Respiratory Protection Mask; Zekler Safety, Ulricehamn, Sweden); (d) 3D facial and (e) clinical images of the 3D-printed face mask, and (f) in combination with protection glasses and a face shield. Note the good clinical fit of the 3D-printed face mask.

3D printing of the reusable components of the individualized 3D face mask

Additive manufacturing of the two reusable components of the individualized 3D face mask was performed by the local 3D printing company 3D Infinity, which was also responsible for the design. A selective laser sintering (SLS) 3D printer (Prodways, Les Mureaux, France; https://prodways.com) and a polyamide composite (PA11-SX 1450; Prodways, Les Mureaux, France) that has ISO/USP Class VI medical certification were used. After 3D printing and cool-down, the 3D individual face mask was sandblasted in the breakout station under vacuum cleaning prior to disinfection (Fig. 1).

Disposable components of the individualized 3D face mask

The individualized 3D-printed face mask requires two disposable components: (1) a head fixation band, and (2) a filter membrane (Fig. 1, Fig. 2). For the purpose of head fixation, a worldwide commercially available Velcro band was used (Fig. 2). A polypropylene (PP) non-woven melt-blown particle filter membrane (Moldex 8080; Moldex-Metric, Walddorfhäslach, Germany; https://moldex-europe.com) was used as a disposable filter membrane (Fig. 1).

Disinnfection of the reusable components of the individualized 3D face mask

Prior to cleaning and disinfection, the two reusable components of the 3D face mask needed to be unscrewed using hand gloves, and the disposable filter membrane and Velcro band were removed and thrown away. Disinfection of the two reusable components of the 3D-printed face mask was then performed using a solution with broad-spectrum antimicrobial action, with a 15-min exposure time (25 ml of Anios Clean Exel 0.5 in 5 litres of water; DD Biolab S.L., Barcelona, Spain; https://www.ddbiolab.com), following the official CORONA guidelines of the AZ Sint-Jan Hospital (Bruges, Belgium) regarding cleaning and disinfection of eye-protective materials in COVID-19 units. After disinfection, both components were rinsed with cold water.