Pneumatic Self Switching Valve Based Ventilator

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The ventilator is powered by a pneumatic self-switching valving system that connects to a steady pressure source and alternates between an on-position and off-position. When the on-position is activated, a controlled positive pressure and flow are directed towards the patient. As the flow switches off by the self-switching valving system to the off-position, natural expiration occurs against a constant low positive pressure (maintaining sufficient PEEP). The control mechanism for switching consists of mechanical components including narrow cross-section flow channels and deformable chambers. A network of these components results in a pneumatic self-switching circuit-analog that lends well to simple first-order modeling. Furthermore, tidal volume, I:E ratio, and frequency can be adjusted simply by switching between set values of individual components in a predictable manner based on our simulation model. Flow channels and deformable chambers are equipped with sliding walls that enable dynamic changes in dimensions. PEEP values and maximum expiratory pressure are set directly by adjusting inlet pressure values using an off-the-shelf pressure regulator.This ventilator design stands out because it is completely mechanical, eliminating the need for any electronic components. This enables the system to run independently without a power supply. The assembly does not contain any external moving parts, thus reducing modes of failure. Moreover, fabrication and assembly are simplified – the pneumatic control unit consists of two layers made of hard plastics that can be 3D printed, and a membrane purchased off-the-shelf. The three components are integrated using the membrane's built-in adhesive. As a result, the entire assembly can be manufactured at a low cost and assembled in a relatively short period of time – just a few minutes.Flow rate versus time data for I:E ratio 1:2 and tidal volume 400cc is available.