A team of Brno University of Technology researchers and students have developed a 3D printable protection half mask that does not require a special material or printer. The product is intended for the general public and can be easily manufactured on regular 3D equipment utilizing the FDM technology (thermoplastic modeling). Although such printers are usually not recommended for such purposes due to the eventual porosity and difficult sealing of the product, the BUT team’s concept involves an original solution to this problem, allowing the use of standard devices.
The BUT-H1 half mask features a very simple structure, comprising:
Compared to a simple 3D-printed version, this original product including a sleeve brings the following advantages:
The protection provided by a half mask, surgical mask, or respirator depends mainly on a tight face fit; the filtering capability of the applied medium is only a secondary parameter. Even improvised filtering instruments substantially reduce the virus contraction risk, although their protective performance cannot match that of a classic tool.
This product is intended for non-professional use, replacing regular surgical masks and respirators when these are unavailable or do not fit on tightly due to improper design or heavy everyday duty. Our half mask does not comprise an expiratory valve, and the humidity aggregates in the filtering medium; similarly to surgical masks, there then forms a potentially bacterial environment, meaning that the filter must be dried and disinfected or discarded.
With many printing materials there is a possibility to perform small shape corrections in order to achieve good fit. In general, only the width of the mask can be adapted successfully. Therefore since the beginning the mask must suit the user in length, i.e. choosing the right size for printing is essential.
To adjust the shape (width), please follow the steps below:
After the printing, the actual half mask body, or frame, and the filter holder both have to be refined by quickly rubbing off (with a knife or sandpaper, for instance) any sharp protrusions or edges that could damage the glove. Subsequently, the selected glove is put on the body and then cut and adjusted conveniently to wrap around the body, forming a tunnel-shaped section.
With the glove already on, a couple of thin rubber ribbons will now have to be inserted in the grooves milled in the body (frame); these ribbons will firmly lock the two structural components of the half mask together.
To obtain the improvised filter, the user can employ materials applied in surgical masks, home air cleaner filters, and similar items. Several different materials can be combined for the purpose, depending only on their air permeability to allow comfortable breathing. The shape of the filter is easy to capture with the guide element (template), which enables the user to quickly copy the lines before trimming the desired medium.
At the next stages, the filter is inserted in the holder, and the holder is attached to the frame. The rubber ribbons at the edge of the frame should ensure firm connection between the two structural parts; the number of ribbons used must be adjusted to their thicknesses.
The headstraps consist in strings or elastic rubber bands sewn or tied to the holder, and their lengths are set to fit the person.
Half-mask front side
Industrial Automation Group
Department of Control and Measurement, Faculty of Electrical Engineering and Communication, Brno University of Technology
The research team thank in particular the Siemens corporation for its long-term collaborative efforts and assistance within 3D modeling and software application, andthe Speltronic company for the materials and information made available.