The principle of operation of this ventilator is to take a bvm ( bag valve mask ) which is widely used disposable device in hospitals and ambulance cars and instead of manually try to ventilate the patient by squeezing it , a control mechanism is used to automate the squeezing process to supply the patient with the required mixture of air and oxygen . the squeezing mechanizm consists of a dc geared motor driven by an H=bridge driver and controlled by an arduino uno board to move an arm coupled to the motor shaft in order to squeeze the bvm bag.

The amount of air goes to patient which is called Tidal Volume using medical terms depends on how much force is applied to squeeze and this can be controlled using a feedback signal from the motor current since as we increase the force or tourque the motor current increases and this is adjustable using a potentio – meter connected to one of the arduino analogue inputs.

On the other hand the breathing rate can be controlled using two push buttons one for increasing the rate and another one for decreasing it.

Also the I/E ratio which is inspiration to expiration ratio or inhale to exhale ratio is fixed in the software to be 1:2 and this is the most used ratio for adults.and this means that one third of the breathing time each time is for inhale and the rest two thirds is for exhale and for the time being we are not controlling this ratio , but in the future versions we will have control on this ratio inshallah.