The fully assembled VentiVader.

The VentiVader is a pneumatic ventilator that uses the compressed air available in hospitals, along with two solenoid valves and simple electronics, to pressurize a manual resuscitator and control oxygen delivery to a patient.  A Raspberry Pi is used as a controller to automate opening and closing of the inhale and exhale solenoid valves and read the pressure sensor. 

The initial version of the VentiVader controls the volume of air delivered to patients (tidal volume) by controlling the pressure of the compressed air coming into the inhale solenoid through a manual pressure regulator. A more sophisticated (and more expensive) version are being developed that uses an electronic pressure regulator to automatically control the pressure of the compressed air line, requiring no manual intervention.

The VentiVader consists of the following main hardware and electronic components:

1. Inhale solenoid valve (hooked up to compressed air line) (Cost: 16.99)
2. Exhale solenoid valve (open to the atmosphere)  (Cost: 16.99)
3. Pressure release valve (to prevent overpressure)  (Cost: 9.99)
4. Enclosed acrylic or plastic box that is able to hold pressure up to 30 psi (Cost: $40)
5. Pressure gage for compressed air (Cost: $11.75)
6. Pressure sensor (Cost: $6.50)
7. Differential pressure sensor (for measuring flow rate and tidal volume) (Cost: $12)
8. Raspberry Pi (Cost: $35)
9. Mosfets for controlling solenoid valves (Cost: $3)
10. Pull-down resistors (10k, 120, & 130 ohms) (Cost: $1)

Total cost for critical components: $153.22

The circuit for the solenoid driver for the VentiVader is shown below, with Mosfets and resistors used to drive the solenoid valves. Each solenoid is hooked up to two separate GPIO pins on the Raspberry Pi. The pressure sensor is hooked up to the Raspberry Pi directly via the I2C interface.