Miniaturized Phosphorescence Sensor for Oxygen Measurement


Researchers from the Fruanhofer FEP have developed an innovative blue OLED-based phosphorescence sensor for oxygen ratio monitoring that could be produced at a relatively low cost

Leveraging their expertise in the development of OLED-on-silicon sensors, researchers at Fraunhofer FEP have recently developed a miniaturized OLED-on-silicon based phosphorescence sensor that combines a marker and sensor on a very small chip surface. These sensors are typically used for oxygen ratio monitoring. The researchers say that this technology helps in the development of a miniaturized sensor that could be produced at low cost in the long term. It also offers a fast and precise evaluation.

The researchers explained that many of today’s oxygen sensors are current-based. These sensors have the ability to cover large temperature ranges, but are difficult to miniaturize. Moreover, they are restricted to certain measurement points.


Optical sensors, such as phosphorescence sensors, overcome these hurdles. They are popular alternatives due to their ease of handling and capability of being integrated into existing systems. The reliability, low susceptibility to interference, and simple maintenance of most devices quickly persuade users.

Blue OLED on silicon sensor detects phosphorescence

In the new miniaturized phosphorescence sensor, a chemical marker is excited by modulated blue OLED light. The phosphorescent response of the marker is then detected directly inside the sensor chip. The marker determines the substance to be measured, a typical application is the measurement of an oxygen concentration.

The current sensor emits blue light in an area of approx. 4.7 × 2.2 mm for exciting the oxygen-sensitive marker. In the future, the researchers hope to reduce the size of the entire chip down to 2 x 2 mm.

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”Currently, the sensor is designed to detect changes in oxygen level. We have achieved functional verification of the component with this first setup, and can use the miniaturized sensor chip for oxygen measurements in gaseous environments. In addition, we see the sensor chip as a platform for future developments, such as the measurement of further parameters and deployment in other environmental conditions,” explains Dr. Karsten Fehse, project manager in the Organic Microelectronic Devices group.

Further areas of applications

Thanks to the advantages of the innovative phosphorescence sensor – the small size, the combination of marker and sensor on a single chip, as well as the fast and precise evaluation of the data – the researchers see further areas of application in which the sensor design could be used.

The researchers hope that these sensors could be developed for monitoring and evaluation of cell cultures in very small disposable culture vessels and in bioreactors. “Single-use bioreactors” usually only offer a very small installation space and a limited number of ports to which measurement systems can be connected. In the future, the sensor system will be further developed in the direction of multi-parameter measurements. Monitoring liquids after the filling process in the pharmaceutical sector, in blister packs, and for quality control of oxygen-sensitive drugs is also conceivable.

Scientists of the Fraunhofer FEP will debut the miniaturized phosphorescence sensor for oxygen measurement at Embedded World 2019, February 26 – 28 in Nuremberg at the Fraunhofer Joint Booth in Hall 4, Booth no. 4-470.

More information can be found here. 

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