Pneumatic Self Switching Valve Based Ventilator

grabcad

The ventilator operates on a pneumatic self-switching valving system connected to a constant pressure source that alternates between an on-state and off-state. During the on-state, controlled positive pressure and flow are directed to the patient, while expiration is allowed to happen naturally against a constant low positive pressure in the off-state, maintaining adequate PEEP. Control for switching involves mechanical components including narrow cross-section flow channels and deformable chambers that work together in a predictable manner based on our simulation model. By adjusting individual component settings, tidal volume, I:E ratio, and frequency can be adjusted simply. Flow channels and deformable chambers feature sliding walls that enable dynamic dimensional changes. 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 for its complete mechanical operation, eliminating the need for electronic components, enabling it to run independently without a power supply. The assembly contains no external moving parts, reducing modes of failure. 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, integrated using the membrane's built-in adhesive. As a result, the entire assembly can be manufactured for a low cost and assembled in a relatively short period of time. Flow rate versus time plots for an I:E ratio of 1:2 and tidal volume of 400cc show flow rates in L/min over time in seconds.