Pressure And Oxygen Sensors in Oxygen Concentrators

Pressure And Oxygen Sensors in Oxygen Concentrators

by Seta Davidian, Servoflo

An oxygen concentrator is a medical device that delivers oxygen to a patient. A typical concentrator consists of a compressor, absorption columns with air filters, circuitry, a product tank, and regulator.  

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Oxygen concentrators differ from machines delivering compressed oxygen from tanks filled at a separate location. Instead, an oxygen concentrator takes standard room air, filters out the nitrogen and other gases, leaving only oxygen for delivery to the patient. The block diagram below shows a design for a typical oxygen concentrator.  

Typical oxygen concentrator
Typical oxygen concentrator 

Employment of pressure and oxygen sensors at various points ensures proper creation and delivery of oxygen. For example, a pressure sensor at the product tank measures the tank's level and to ensure there is proper flow moving into the regulator.

Single oxygen-sensing element
Single oxygen-sensing element 

Often times, there is also a pressure sensor between the regulator and outlet oxygen. A stationary oxygen concentrator may use a pressure sensor in the 50-kPa range to detect a kink in the tubing. See figure below depicting a Fujikura AP2/AG2 analog pressure sensor, similar in appearance to AP3/AG3 pressure sensors with threshold detection.  

Fujikura AP2/AG2 analog pressure sensor

For portable oxygen concentrators, a pressure sensor in the 1 kPa range is used to detect inhalation, which then controls the regulator. Here, it is important to use a pressure sensor that is sensitive enough to detect the low flow rate of breathing but can also withstand high overpressures. The AL4 is a good option meeting this requirement. 

Finally, and perhaps most obviously, an oxygen sensor can be installed to sense the oxygen percentage of the air being delivered to the patient. The oxygen sensor allows the designer to create alarms and set points for the filtering portion of the concentrator. 

The abundance of sensing technology allows for the development of more flexible medical equipment with more features and functionality. This description of oxygen concentrators is one example of where the evolution of technology has created better health for all. Download a Fujikura AP/AG Series Product & Pricing Guide at  

Servoflo Corp.

Lexington, MA