Device Components | oxygenflowmechanism

Oxygen Tank

Oxygen can be supplied to patients through hospital supply of oxygen or portable oxygen tanks. Oxygen can be delivered from the OFM in two delivery methods:

1) Costant air flow - Standard way that oxygen is delivered

2) Intermittent flow - Oxygen delivered to the patient only when the patient is inhaling. This method also conserves the amount of oxygen that is used.

This device can also change the flow rate of air supplied to the patient.

Arduino Mega

The Arduino Mega is a reliable microcontroller that is capable of controlling all components of this system. The Arduino Mega is responsible for performing the following tasks:

1) Reading the pressure values in the cannula to determine and alert medical staff of breathing changes and cannula removal.

2) Controlling the solenoid valve to change the flow of oxygen to the patient.

Proportional Control Valve

Proportional Control Valve is a solenoid valve that controls the amount of oxygen that is allowed to flow through to the patient. Additionally, it is used in tandem with other parts of the system to test if a patient has removed his/her cannula. The solenoid allows pulses of oxygen to be delivered to the patient. If no response to the oxygen is given, an alarm alerts medical staff that the patient has stopped breathing.

Amplifier Circuit

An amplifier circuit is used to drive the solenoid valve. A combination of resistors, op-amps, diodes and a transistor make up the amplifier circuit. The circuit is powered by an external power supply and the output is controlled by the arduino using pulse width modulation (PWM). An RC filter is used to convert the arduino PWM waveform into an analog signal. An analog signal is important because the valve is not an on/off valve but rather a variable valve and thus the valve depends on an analog input.

Pressure Sensor

The pressure sensor is used to read the patient nasal pressure. The pressure readings indicate the breath phase of the patient (either inhaling or exhaling). By reading negative pressure, the pressure sensor is able to indicate that the patient is inhaling. Similarly, by reading positive pressure, the pressure sensor is able to indicate that the patient is exhaling.