During the Covid-19 crisis, Chromatic 3D was approached with an urgent need for a critical ventilator part known as a Positive End Expiratory Pressure, or PEEP, valve adapter. The part had gone out of supply due to increased Covid-19 demand. We quickly designed a solution which employed a Digital Mold™ for Reactive 3D printing™ combined with traditional stereolithography (SLA), that would satisfy the need without employing costly injection mold processes.
PROBLEM DESCRIPTION: A Ventilator Part in Short Supply A PEEP valve is a seldom used medical device consisting of the PEEP valve itself and an adapter placed over an MDI port. Chromatic 3D Materials was asked to design a solution for producing the adapter.
PEEP Valve: As COVID-19 attacks the alveoli in the lungs, it can cause a collapse resulting in extreme respiratory distress and potential permanent lung damage. The PEEP valve prevents the alveoli from collapse by providing backpressure to keep the lungs from fully deflating.
PEEP Valve Adapter: In normal ventilator set-ups, exhaled air escapes into the ambient air of a hospital room. Air exhaled by COVID-19 patients is contaminated with Corona virus however, which puts other patients and medical personnel at risk of infection. The PEEP valve allows addition of an air hose to the ventilator set-up to divert exhaled air to a safely contained ventilation system.
WHY LIQUID REACTIVE 3DTM PRINTING?
Chromatic 3D Materials was tasked with satisfying a unique combination of requirements with an inexpensive, fast, just-right solution.
SPEED: Traditional manufacturing injection molds were not available. The production of new injection molds was cost prohibitive and had lead times likely exceeding the peak of COVID-19 infections when the PEEP valve assembly would be most needed.
MATERIAL PROPERTIES: Flexible, airtight and rugged, the adapter part has very specific requirements in that the seal must be highly flexible with a Shore A Hardness of 55, but still have solid material properties that produce an air tight seal. It also has to be rugged enough to withstand repeated assembly and disassembly by medical personnel under hasty conditions. This level of durability cannot be satisfied by normal 3D printed thermoplastic elastomers. Liquid Reactive 3D Printing™ provides uniform parts suitable for the PEEP valve assembly as well as many other applications.
THE SOLUTION: The Chromatic 3D Materials team, in strong collaboration and communication with the customer, developed a novel solution employing two different printing technologies: Liquid Reactive 3D Printing™ and SLA to meet the design specifications of the customer. We designed a Digital Mold™ for our elastomeric resin to print (and reprint as needed) a specially designed PEEP valve adapter (1) and (2) and also SLA printed the mating rigid adapter body (3).
The material chosen for parts 1 and 2 was Flextune 60 with a Shore A Hardness of 55-60, a tensile strength of 4.5 MPa at 100%elongation, with an elongation at break of 575%and a peak stress of 23.4 MPa. The choice of resin reflects the high requirements around flexibility and durability for this part.
