Together with Prof. Tauber's institute, Eschweiler GmbH, Scienion AG and the Fraunhofer Institute for Telecommunications, an SME-innovativ joint project was obtained. The title of the project is: Optical micro ring sensor for quantitative determination of electrolytes.
In the human body, the electrolytes sodium, potassium, calcium, chloride as well as hydrogen ions (the pH value) play an important role, e.g. for the water balance. The concentration of electrolytes in the blood is checked very frequently in medical diagnostics, including kidney disease, heart failure, alcohol intoxication, diabetes mellitus and diarrhea. Disturbances in electrolyte concentration have dramatic consequences. For example, when sodium ion concentration is too low (hyponatremia), brain cells can swell, causing coma. Hyponatremia often occurs when treating children in the hospital who need to be given fluids after surgery or for diarrhea. Blood sampling is difficult in small patients and only small blood samples can be obtained.The currently used automatic blood analyzers contain a separate probe (ion-selective electrode) for each type of electrolyte. This measuring principle requires a certain sample volume so that all measuring probes can be overflowed. The volume of blood that can be taken from infants is often insufficient for this purpose. The aim of the "optION-Sensor" project is to explore a new measurement principle from photonics that enables the analysis of very small blood volumes. Optical microring resonators (MRR) are used for this purpose. An MRR is a ring-shaped light guide through which laser light is directed.
When a substance is deposited on the surface of the MRR, this changes the optical properties of the resonator. The change in properties is proportional to the amount of molecules deposited. Since even the smallest changes in the optical properties can be measured, a very small amount of substance can be detected with a high degree of accuracy. The MRR are coated with capture molecules (ionophores) for specific binding of the electrolytes. By combining them with a microfluidic module, several differently coated MRR can be overflowed with a blood sample. Thus, all electrolyte concentrations can be determined from less than 20 µL of blood.
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