HensNest

Last crawled date: 1 year, 10 months ago

The HensNest

About the Design
The HensNest was created to address some of the most pressing issues with current face mask hacks. It was inspired by both The NanoHack by Copper3D and the DIY Face Mask by Mark Fuller. The HensNest has a flexible printed hoop frame that conforms to the face without post-processing steps, like using a heat gun or applying a sealant. The filter surface area is very large, addressing issues with the breathability of hard-sided mask designs with small filter towers, like The NanoHack. The HensNest adds a tented structure to the design that keeps the filter surface away from the mouth and nose, which we learned from our clinical collaborators is critical for keeping the filter dry and functional during extensive use. Lastly, this design is mostly planar and is fast and cheap to print. If you have design improvement suggestions, please post to the comments section below.

Release Notes for v1.0
We released HensNest v1.0 to give the maker community a chance to further “hack” our improved wireframe design. We will continuously release design improvements and updates related to the wireframe design and all of the release notes listed below.
1. ASSEMBLY: Assembly for The HensNest is similar to the DIY Face Mask by Mark Fuller and involves first securing the disposable filter within the wireframe. Rubber bands or elastic straps should be connected at the four tabs on the wireframe to create two continuous loops around the head, similar to a disposable N95 mask design. We will release detailed assembly instructions and an assembly video very shortly.
2. STERILIZATION: The HensNest was designed with the intention of having a disposable filter (more on that in a sec) and a reusable wireframe. We recommend printing the wireframe in ABS to allow for both heavy disinfectant use and steam sterilization via hospital sterilizer or home dishwasher. If you’re printing in PLA/PETG, recognize that it will likely not be tolerant to steam sterilization but should not excessively degrade with bleach or alcohol disinfectants.
3. FILTERS: Right now, we are experimenting with different filter types to achieve as close as possible to an N95 rating (knowing that we will not really achieve N95 rating). At present, we are testing vacuum cleaner bags, household heater air filters, and any other common filters we can get our hands on. We are fortunate to have an environmental safety and health officer at our institution who can run both qualitative and quantitative respirator fit tests. We will post these results as we get them. If you have suggestions for other filter types, please post to the comments section below.

About the Team
The HensNest is a collaborative project from the University of Delaware’s (UD), home of the Blue Hens. The design was conceived and early prototypes manufactured in The Design Studio , which is an undergraduate teaching and learning makerspace in the UD Department of Mechanical Engineering. The project is led by Mr. Whitney Sample, Co-Director of The Design Studio and an industrial designer by training, with extensive experience in medical device design At this time the HensNest design is still a work in progress after several long days in the Studio. Design and CAD support for the project was provided by Design Studio teaching assistant Arnav Prasad, with logistical support from faculty members Prof. Jenni Buckley and Prof. Ajay Prasad. Extensive clinical consultation and inspiration was provided by Dr. Lisa Lattanza, Chair of the Department of Orthopedic Surgery at Yale University and Co-Founder (with Prof. Buckley) of The Perry Initiative. The group would also like to thank Mike Gladle from UD environmental health and safety and all members of UD’s MakerNetwork and College of Engineering who helped with project logistics.

Liability
The HensNest should be used only as a last resort when FDA-regulated masks are not available for home or medical use. At present, the HensNest has not been tested using either qualitative nor quantitative respirator fit tests. We will post these results as soon as they are available, along with our recommendations for filter materials. The HensNest design files and manufacturing notes are presented “as is” in a good faith effort by all parties to help with the COVID-19 pandemic. If you use, copy or share this Item, you agree to utilize these files for production of masks at your own risk and comply with any state and federal guidelines for use of these devices. You also agree that HensNest team members and their employer: (1) Disclaims any warranties related to fitness of use, non-infringement, or compliance with regulatory standards; and (2) Have no liability for any claims of any kind made by person, either as a result of use of or as related to the Item.

some design questions we received:
1. What keeps the filter media in place/taught around the perimeter? Will this sag/make contact with the face, re: wicking/saturation? 2. The tabs that connect the frames appear to protrude beyond the plane that makes contact with the face...is this a comfort or seal issue? 3. What is the filter media? 4. Intended strap material?

Keeping in mind it's a work in progress, with nearly as many questions, as answers.. 1)as presented, currently nothing.. I've played with multiple options, but not settled on one yet.. because they either dramatically increase print time/complexity or ruin the simplicity that seems to offer the broadest comfort/fit range.. 2)while they aren't noticeable comfort-wise, that's not to say they aren't an issue I'd like to address.. 3) the filter media I was using, was taken from a HEPA furnace filter.. without knowing yet whether one layer, or more are needed..

this concept was meant as a stepping stone to the original hoop idea, which scores point for simplicity, speed of print, and broadest range of fit/comfort.. where it loses points is not forcing a stand-off distance to avoid moisture wicking and failing as a barrier.. this first test, for the purpose getting something in hand as quick as possible, does not change the original hoop.. the larger holes, being used for the four-legged stand-off structure was originally intended for elastic straps.. therefore a better attachment point for straps, might need to be added.. though I was able to put rubber bands around the leg base and accomplish the same thing.. it's not the most elegant.. a bigger issue that needs to be worked out, is our first flexy legs are probably far stiffer then needed.. and because of that they distort the original hoop, unacceptably.. but I think a better balance of material thickness in appropriate locations can fix this, and keep the comfort/fit plus points

the original thought was going with an ABS material to allow for higher levels of sterilization.. but the practicality in the open source market isn't there.. there would be no way of identify which version printed from a variety of sources, was suitable to be Autoclaved.. so we focused on quick to print, simple to assemble..

my 'ideal' was to see if we could heat press/form the raw HEPA furnace material in a similar fashion to how it's done on the industrial scale.. I was hoping to get mold shapes printed in Stratasys Ultem material which can handle high heat.. glass transition of 422 F, which should be enough to thermoform the filter material.. Further along those lines, I had really good success heat sealing the material together.. with basically a soldering iron.. I'm looking to try this afternoon with a rolling heat sealer we have in the Studio.. if it works, there could be multiple possibilities.. putting filter on either side of the structure, encapsulating it and welding the multiple layers together at the perimeter.. the other is welding it to the hoop base itself..