The development is on-going and rapid. The Introduction Video for version 7 published for the Virtual Maker’s Faire was just a stepping stone along the way.
Version 8
Version 8 was meant to address the change is atmospheric pressure due to weather. It turns out that the pressures needed for ventilators is quite trivial in a structural containment sense. In the units used by the medical industry, average ventilator pressures are only 10 centimeters of H2O. This is relative to the current atmospheric pressure. Unfortunately, going from a sunny, high-pressure day to a rainy, low-pressure day can result in an atmospheric pressure change of around 30 centimeters of water. Version 7 took a bunch of readings to get a baseline average pressure. This was fine for initial development, but for a device that will run continuously for even one day, this is not an acceptable solution – The baseline would no longer be valid. A second pressure sensor outside of the pressurized area is required. This required a significant change in the housing to have a pressure zone and a non-pressure zone.
Version 9
Version 9 – Leaky! The air valve design for Version 1 through 8 used a nice smooth quarter-turn valve. No restrictions when open. The goal of the old valve was simplicity, robustness, and 3D printer tolerance. After switching to the air-blower pump, flow and pressures were quite sufficient. As was seen in the version 7 video, with the pump only using 18% power, 10 centimeters of H2O was easily sustained. Cycling totally on and totally off also worked without issue. Serious programming began in version 7, then 8 on fine control of the pressure curve to achieve the sought-after pressure curves. This is where the Valve Version-1 fell to its knees. Though it flowed like a river when open… it flowed like a small stream when totally closed. It didn’t have enough restriction. Valve Version-2 is a complete re-design and now uses a gasket. Initial testing looks promising.
Version 10
Version 10 is a re-think on the housing to facilitate better pressure isolation and confinement. Also, improvements were made to ease assembly and more importantly, improve disassembly for maintenance and cleaning for the next patient. All learned from versions 1 through 9.