How Do Oxygen Sensors Work?

Oxygen sensors are devices that measure the proportion of oxygen in the liquid or the gas being analyzed.[source] Today, these sensors are used in various industries. Each industry uses a specific type of oxygen sensor depending on the application or the environmental conditions.

In this blog, we have discussed oxygen sensors that find their applications in the medical industry. So, let’s dive into it.

Oxygen Sensors Widely Used In Medical

Currently, five types of oxygen sensors are used in the industry. Let’s take a look at them:

Oxygen Sensors

1. Electrogalvanic sensor

The electrogalvanic oxygen sensor is a fuel cell-based sensor, which is generally used in scuba diving equipment & anaesthesia ventilators. [source]

This sensor helps to measure the level of oxygen by producing an electrical output that is directly proportional to the oxygen levels. Similar to the electrochemical sensor, the electrogalvanic sensor gradually consumes itself due to oxidation.

2. Ultrasonic Oxygen Sensor

These sensors use sound speed to measure the amount of oxygen in liquid or gas.

For liquids, upstream & downstream sensors use the velocity difference between high-frequency waves to know the oxygen levels. Whereas in gases, the variation in sound speed due to the variation of gas composition helps to measure the oxygen levels. [source]

Ultrasonic oxygen sensors are widely used in anesthesia ventilators and oxygen concentrators.

3. Infrared Oxygen Sensor

Infrared oxygen sensors are used in oximeters to measure the oxygen levels in the blood. These devices are used for personal medical monitoring of oxygen saturation.

How do they work? The sensor measures the oxygen saturation in the blood through light. The infrared light & red light are pulsed together through a thin skin layer and then measured via a photodiode. Measuring the lights of different wavelengths helps to measure the oxygen saturation in the blood.

4. Clark Electrode Oxygen Sensor

This is an electrochemical oxygen sensor that measures the oxygen levels in liquid using a cathode & anode submerged into an electrolyte.

This sensor was basically invented to measure oxygen levels during cardiac surgery. Currently, it has found its application in portable blood sugar level measuring devices.

This type of sensor is only accurate to one-tenth of actual oxygen levels. However, due to its low cost, it is widely available as consumer goods around the globe.

5. Optical Oxygen Sensor

The optical oxygen sensor works on the principle of quenching fluorescence by oxygen. As they use light to detect oxygen levels, these sensors are highly accurate. Therefore, these oxygen sensors are replacing Clark electrode sensors. [source]

The working principle is that when certain molecules are exposed to light, they emit light energy or fluorescence. However, in the case of oxygen molecules, the light energy is absorbed and therefore, less fluorescence is observed. Therefore, when the sensor detects less fluorescence, it means the oxygen saturation level is higher.

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