We had a copy of the bellows 3D-printed in TPU on a HP Fusionjet. This material is quite a bit stiffer than the silicone we used (Shore 90 vs Shore 50) but this technique could provide an alternative solution to injection molding.
The bellows has been mounted in a test machine and is run through cycles in a longevity test. Measurements show the motor needs to put out 25% more power to actuate the more rigid bellow, but the controller seems to behave identical to the blue bellows.
We took delivery of the 50 Series 1 machines from Audi last Friday and started putting in the motherboards the next day. Thanks to Jarne, Brecht, Hendrik, Martin, Mohammed, Rupert, Rayan & Roald for the help putting the machines together over the next days.
The boards needed a couple fixes but are working. Sensor modules are working. We have about 25 machines fully built-out now. Number 1 to 13 will stay in Belgium and will be used for tests, both in-house and at partner locations.
The other machines will be sent out early next week to other research groups in Italy, Canada, Brazil, Jordan & Spain who are interested in testing & co-developing the ventilator.
The 50-machine-run at Audi & all the component sourcing involved has proven the validity of the design approach for rapid-manufacturing. Using their manual assembly line, Audi can output one assembled machine frame every 2 minutes.
Branimir & Bruno have been running the machines through the functionality tests specified in the MHRA-document, Simon has been finalizing the end-of-line tests.
The interface has come together; Thomas, Tom, Loes, Frank & all have been bug-fixing most of the week
Sourcing the medical parts (respiratory valves, PEEP-valves) has proven troublesome. Theo and Ben have designed 3D-printable versions, and have been producing these. We are using them for on the 25 test setups for now, but may develop them for compliance with medical use.
We have been demonstrating the machine & collecting feedback. The design requirements for version 2 are taking shape.
Koen Vanden Boer, at the Flanders Make testsite in Lommel has been performing endurance tests on the Ambu bags. With the plunger from prototype 8 we had bag failure at 50’000 plunges. We need to achieve 600’000 repetitions at full volume to safely use the machine for 2 weeks. The new plunger design has achieved 500’000 plunges and is still going. An additional 8 test stands have been installed and are pumping away to achieve more statistically valid results.
Parallel to testing version 1, Jef aims to have a first mechanical prototype of version 2 finished by the end of the week.
However, with the pc-interface, the aluminium frame & the electronics the machine is developing into a solid, professional design. The bag has, at least in perception, become the weakest link.
We intend to quantify & document the durability of the Ambu bag concept and fully evaluate the performance of version 1, but it is becoming highly likely version 2 will have a custom-built bellows, replacing the Ambu bag with a more durable solution.