Development of prototypes of half-mask facepieces for Koreans using the 3D digitizing design method: a pilot study

In the Korean market there are several respirators for industrial purposes. Some of them are imported from global manufacturers such as 3M, and the others are developed by domestic companies. However, some of the locally made respirators have a face-seal leakage problem because they were not designed taking into account Korean facial characteristics. This pilot study was conducted to develop three face models for a half-mask based on the Korean fit-test panel and also to design three well-fitting silicon prototypes (large, medium and small) for Korean faces. For a test panel, 50 subjects were selected on the basis of lip length and face length. Shapes of faces from the test panel were scanned by a 3D scanner (Vivid 900, Minolta). The facial dimension scales for three size groups were established through statistical analysis. To ensure that the shapes fit the mean facial dimensions of each size group, similarly shaped sample faces were selected from the test panel. Mean faces with representative facial dimensions as well as face models (mannequins) were made by the Rapid Prototyper (RP; Z400, Z Corps, USA). These were reshaped to fit the mean faces by clay-modeling. The face models were digitized to recheck the fit of the facial dimensions. On the basis of the face models, three types of masks were developed through digital modeling, and tangible models were prototyped by RP. Three differently sized prototype masks were made with silicon and examined by simple naked eye test. This procedure established the mask design process based on digital technology; it can be applied for similar design projects in the future. Further study is needed to verify whether these prototypes would be a good fit for Korean faces.