Disclosed are devices, systems, and methods, including an oxygen delivery device that includes an oxygen delivery module to produce at least concentrated oxygen, a gas moving device to deliver air to the oxygen delivery module, at least one motor to controllably drive the gas moving device, an energy source to power at least the at least one motor, a pressure sensor to determine a pressure level, and a purity sensor to determine oxygen purity value. The device also includes a controller to control, based on the oxygen purity value and the pressure level, at least the gas moving device's operations and the oxygen delivery module's operations to cause the pressure resulting from gas moving device to be substantially at a pre-determined pressure value and to cause the purity level of the oxygen produced by the oxygen delivery module to be substantially at a pre-determined purity value.