Phosphorus is a major constituent of many fertilizers. In the future, the substance will continue to play a key role in agriculture in order to produce sufficient food for the growing world's population. As no phosphorus mines exist in Germany, phosphorus has to be recycled from sewage. For this purpose, the concentration of phosphorus has to be analyzed in liquids. Methods known today are characterized by a high consumption of chemicals and a high time and staff expenditure.KIT scientists of the Institute of Functional Interfaces (IFG) have now developed a simple phosphorus detector that does not consume any chemicals. The researchers coat a silicon wafer with a sensor layer that is continuously exposed to an infrared beam. The sensor is then wetted with the liquid to be studied, such as sewage. As a result, chemical composition of the sensor layer is changed specifically as a function of the phosphorus content of the liquid. This change can be measured quantitatively by means of infrared spectroscopy. After calibration of the measurement system, the exact phosphorus concentration in the sample can be determined. After measurement, the wafer with the sensor layer is heated to 1000°C, regenerated, and can be used for the next measurement.The phosphorus detection method developed by KIT has several advantages compared to other processes known: The new technology does not require any chemicals and the samples to be analyzed do not have to be processed. The method can also be automated and is easy to handle. The sensors are inexpensive in production and can be reused several times. Finally, the detection principle based on infrared spectroscopy cannot only be applied to phosphorus, but also to other substances.The KIT looks for cooperation partners to optimize and commercialize the process.