Portable, Low Cost, Closed-Loop Mechanical Ventilation Using Feedback from Optically Isolated Analog Sensors

This paper focuses on the development of a precise, user-adjustable breathing cycle for mechanical intervention in patients suffering from respiratory problems. Controlled breaths are provided using a closed loop system with feedback path from two self-calibrated sensors i.e. a pressure sensor and a flowrate sensor. User-input through a Graphical User Interface (GUI), displayed on touch screen module, will act as control signals. It is in response to these signals that the breathing cycle will adjust. Raw data from sensors is optically insulated and converted into variable duty PWM signals for precise, error free readings. The cycle is digitally controlled with a wide range of settings so that it is adjustable from patient to patient. DC piston air pump, with modified buck converter as speed controller, is PID tuned and is replaceable with similar pumps after tuning. Sensors are also replaceable by modeling their behavior to appropriate transfer functions. The result is the design and making of a low-cost, portable prototype that can be used in ambulances, small hospitals and during disaster management to provide volume and pressure-controlled air for mechanical ventilation.