I created a reusable version of this respirator specifically design for law enforcement and other first line responders. This project is moving along very quickly and I will update this page periodically as it progresses.
Link to project submission with the National Institute of Health 3D Print Exchange
Marketing landing page for the project with a description and photos
Github repository with source files, flat patterns and assembly instructions
Problem & Background
Problem 1: Disruption of the supply chain
There is a worldwide shortage of N95 respirators and few manufacturers that are allowed to produce them. To mitigate this, the CDC recommends that healthcare workers reuse their disposable masks. Some don't have any protection beyond a standard surgical or cloth mask. The US gov recently purchased a large quantity of disposable N95 respirators at a price of $5.50 each, nearly 8 times what they paid for the same masks in February.
Problem 2: Design issues with current models
Disposable respirators are lightweight, but don't always form a tight seal and fog up glasses. Reusable respirators are heavy and uncomfortable to wear. Healthcare workers are complaining of sores on their faces and ears from wearing them all day. When they are under stress, it becomes even more difficult to care for their patients. 3D printed designs are easy to reproduce and have helped to fill a need quickly, but they do not fit the face well and introduce gaps, take a long time to print and use a large volume of material. They also have to be sanitized between uses.
Solution summary in simple terms
The Basic Respirator is folded or sewn from a flat pattern into an origami-like structure that is both lightweight and rigid, but still flexes to conform to the curves of the face allowing the wearer to talk and yawn without creating a gap. A 3D printed filter enclosure accepts an N95 or substitute filter and a soft neoprene strip forms an airtight seal. The mask, filter assembly and filter use very little material and the disposable version can be discarded/recycled after each use. It is cool and comfortable to wear. The entire mask weighs 19g and the filter assembly requires 9.5g of filament.
The disposable version of this device is made from Tyvek and designed for healthcare workers treating COVID-19 patients, although the design is highly adaptable and with different materials the same pattern can be adapted for other front line responders and high risk individuals.
Both the disposable and reusable (pictured) versions of this device are designed to be produced in mass quantities and the disposable version can be shipped flat as a kit for onsite assembly - the IKEA of N95 respirators if you will.
Solution summary in technical terms
Recommended Materials - Disposable Version
• Tyvek™ 1073B, a high-density polyethylene that's antimicrobial with a bacterial filtration efficiency between 98 and 99%. It's breathable, durable, tear resistant, meets regulatory requirements, is widely in medical packaging and compatible with sterilization processes. It bonds to adhesives well and doesn't seem to cause paper cuts.
• Several types of filters can be inserted, depending on availability
- Halyard H600 medical sterilization wrap
- MERV-15 air filters
- HEPA filters
- 4+ layers of high density non-woven polypropylene
• Antimicrobial neoprene for the inner seal and gasket
• Autoclavable double-sided adhesive
• Self adhesive medical wrap or non-woven polypropylene for the straps
• Aluminum 85mm nosepiece
• Form Labs' Surgical Guide Resin and Dental Resin are autoclavable. The VA also recommends printing respirators in Nylon using MJF. For FDM printing, PETG is preferred, although the VA does not recommend this method because FDM prints have microscopic holes.
Recommended Materials - Reusable Version
• I am currently prototyping and testing various materials
State of advancement of the project
Prototyping & Testing
I started this project on March 25th. The respirator is now a fully functional prototype and I'm shipping test kits to hospitals. My primary goal is to get the prototype clinically tested and evaluated. In the meantime I am testing myself and iterating the design so it's better, safer and easier to make.
Production & Manufacturing Research
I have assembled the masks by hand and with a 3D printer and am now lasercutting the materials to determine appropriate settings. Lasercutting is ideal because it can both cut the material and score fold lines and guidelines to reduce manufacturing and assembly time. CNC and die cutting are two alternatives.
Phase 1: Initial testing / review & collect feedback
• Collect user feedback from clinicians at hospitals and improve the design.
• Order a qualitative fit test kit and conduct testing
• Document settings and process for laser cutting
• Update the website with assembly videos and instructions
• Update the website with a "community use" version of the mask with materials guide
Phase 2: Federal review & approval
• US review with Veterans Health Administration and FDA to authorize for emergency use only.
• Test various filter materials
• Create a bill of materials
• Create a tech kit for manufacturers
Phase 3: Source manufacturers and suppliers
• Submit BOM & tech kit to manufacturers and gather quotes for mass production
• America Makes is an additive manufacturing organization that is working with the NIH / VA to source manufacturers and connect them to hospitals with PPE needs.
• For the reusable version of the mask I would look at alternate manufacturers in the soft good industries, specifically those that produce backpacks, winter gear, moto gear and tactical gear.
The testing requirements for FDA approval are outlined here: https://drive.google.com/open?id=10cOATGpWCUw9SjWLr7Isc12VEwgoBttY9aFKetomjGo
My testing at home includes:
• I've fit tested the mask on a male face with different features than mine (larger, longer, more pronounced nose, less pronounced chin).
• I can tell that the mask is sealed because of a slight vacuum effect when breathing deeply and opening the jaw to talk does not cause gaps Video of preliminary fit test
• I've tested the mask by spraying fragrant aerosols 8-12 inches in front of the filter and can only faintly smell them.
• I've worn the respirator for 2 consecutive hours and off/on all day without needing to make frequent adjustments. Breathing was a bit labored but comfortable -- similar to other respirators. The mask is much cooler to wear.
• I can perform strenuous activity (push ups, running up several flights of stairs) without becoming lightheaded.
Results / Expected Results
• I expect that the device will pass the qualitative fit test either on the first pass or with minor design revisions.
• I also expect it to pass fluid resistance test since Tyvek is already determined to be fluid resistant.
• Perceived effort of breathability is more subjective and also dependent on the amount of activity that a doctor or nurse is required to complete while wearing this mask.
• I do not expect to receive nor do I need FDA authorization for this project to be successful. But it would be a great exercise to work with them to approve an open source medical device.
Safety, quality Assurance & Regulation
I've researched NIOSH certification, OSHA fit test requirements, ATSM safety standards and FDA requirements for Emergency Use Authorization for N95 respirators, which are considered a class II device. This would be the highest level of approval, but as mentioned previously, even if it does not meet class II requirements, it can still be clinically approved and produced on a smaller scale. I am not familiar with regulations in other countries but would be motivated to learn if there is interest.
Impact, Issues and Risk
• Giving healthcare workers a day of clean breathing and feeling of safety would have an immediate impact on their comfort and ability to care for their patients.
• Mass producing devices such as this will make a dent in the shortage to reduce the spread of transmission, starting with healthcare workers, then high risk individuals, grocery store and foodservice workers, delivery drivers, law enforcement and travelers.
• If I am able to have any measure of control over who gets supply I will distribute them to hospitals that serve disadvantaged communities first. They are the hospitals that I am currently working with and receive the fewest emergency supplies from our federal government.
• Providing an open source alternative for N95 respirator design may help prevent respirator shortages in future pandemics.
• There are other uses for respirators beyond pandemics and this may provide a way to protect those who need it but may not have access.
I realize my goal for this project is ambitious and the design may not be approved. Even so, I want to push it as far as possible in case it might inspire others to think differently about respirator and medical device design. So far I've had people from 6 continents and 50+ countries visit my website and it is encouraging that people from so many different regions are interested.
• If the device fails it could seriously harm or cause someone to die if they contract the virus.
• While flat pack shipping seems like a clever option, on-site assembly means giving up some quality control and could introduce safety issues. NIOSH certification requires yearly inspection of manufacturing facilities. I am mitigating this by producing videos of assembly and fitting.
• Finding a manufacturer to produce these masks may prove difficult because of fear of litigation, even though the rules have been temporarily relaxed.
• DuPont, the manufacturer of Tyvek, states that the product is not recommended for respiratory applications. They mentioned the use of Tyvek as filters specifically. They have not yet assessed my design and provided an answer on whether my particular application is an exception because I am using Tyvek for structure and protection, not filtration.
• During calmer times, 3M sells advanced models of disposable N95 respirators to the US gov't at a cost of $1.50 each and still makes a profit. I am not sure what the per unit cost would be to manufacture the design even if it is approved.
• I designed this project based on my own assumptions and intuition. I've researched respirator design and regulations to the best of my ability (and in this short timeframe), but I'm still an inventor at heart so my emotional investment may be preventing me from being fully unbiased. I need an uninvolved party to offer a critical view to reduce the risk that I've designed something ineffective and unsafe.
The project team is just me (Hunter Futo). I have enough experience with soft goods industrial design and manufacturing, CAD and digital fabrication to have produced a prototype and begin a conversation with manufacturers. I am learning the rest very quickly.
Basic Respirator by Hunter Futo is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.