Next-Generation Custom-Fit Reusable Respiratory Protective Device with Continuous Fit Monitoring - Part I: Custom-Fit Design.

Filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in relation to accommodating the fit of some sex and race combinations. This study presents the development of a custom-fit respiratory protective device (RPD) which conforms to a user's facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this three-part series of papers, we design, develop, and successfully demonstrate the realization of a custom-fit reusable RPD comprising the technology building blocks of a base frame, a covering piece, interlocking screw sets, a fastening hub, and a continuous fit monitoring system. By facilitating the customization of the RPD - ensuring the right fit and choice of filter with the desired degree of filtration - this device may have high acceptability by the public, including children, for whom RPD options are currently limited. In this first paper, we develop the methodology, including the algorithms, for automating the design and production of custom-fit RPDs from digitally scanned facial profiles of individuals. We propose a taxonomy of anthropometric facial landmarks for customizing an RPD for an individual. We demonstrate the successful application of the taxonomy by creating digital prototypes of custom-fit RPDs for three individuals with different facial profiles.