Phosphorescence sensor integrates blue OLED for marker excitation
Their first sensor prototype was designed for oxygen ratio monitoring. Most of today’s oxygen ratio monitoring sensors are current-based, they explain, they are difficult to miniaturize and restricted to certain measurement points. In the new sensor, a chemical marker is excited by modulated blue OLED light and the marker’s phosphorescent response is then detected directly inside the sensor chip. Integrating the OLED control and the sensor front-end all on one silicon chip makes this sensor potentially very cheap to manufacture and miniaturize for multiple markers. Barely the size of a thumbnail, the phosphorescence sensor developed so far consists of a blue OLED integrated together with a commercially available marker on the silicon chip.
”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.
The current sensor emits blue light in an area of approximately 4.7×2.2mm for exciting the oxygen-sensitive marker. The decay time of the light emitted by the marker after excitation is a parameter of the oxygen concentration of the environment. The significantly lower phosphorescence signal is recorded via integrated silicon photodiodes, amplified locally in the chip and subsequently evaluated in relation to the excitation signal with regard to the phase shift. In the future, the chip could be significantly reduced in size to measure less than 2×2mm.
The researchers anticipate that similar sensors could be developed to monitor and evaluate 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. A more advanced sensor system could measure multi-parameters for monitoring liquids after the filling process in the pharmaceutical sector, in blister packs, and for quality control of oxygen-sensitive drugs. The Fraunhofer FEP is seeking project partnerships to further develop the sensor platform.
Fraunhofer FEP – www.fep.fraunhofer.de
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