Measurement of multiple water parameters in parallel with a single sensor chip

     The Fraunhofer Institute for Photonic Microsystems (IPMS) has presented a breakthrough integrated technique for the simultaneous measurement of various water parameters using isfet. The newly developed N-well integration technology makes it possible to measure pH and nitrate, phosphate and potassium concentrations in parallel and continuously using only one sensor chip. This innovation opens up new horizons for environmental and bioanalysis.

     Isfet is compact, durable and easy to integrate. This makes them ideal for precise pH measurements and accurate determination of many ion concentrations in water, making them powerful tools for environmental and biological analysis. Due to their resistance to breakage, they have been widely used in pH measurement techniques, especially in food production. The company has now developed an N-well technology that integrates multiple ISFETs on a single chip to achieve specific functions through an ion selective layer.

     This integration technology opens up the possibility of multifunctional ISFET arrays. In collaboration with research partners, more application-specific ion-selective coatings can be developed and integrated in the future. This allows simultaneous and continuous measurement of different parameters such as pH, nitrate, phosphate and potassium concentrations with just one sensor chip. Other parameters can be integrated into the system as needed.

     "This measurement system, which allows continuous real-time recording of basic water parameters, has great market potential," says Dr. Olaf R. Hild, head of the Chemical Sensor Technology division at Fraunhofer IPMS. "This opens up new possibilities for applications in environmental analysis, agriculture and water management, and the rapidly growing market for indoor agricultural applications." "And," he adds with a laugh, "with this technology, we have a unique position in Europe!"

     The use of this technology should improve the efficiency and sustainability of agriculture by combining measurements with external inputs, such as weather data. This will allow farmers to apply nutrients more precisely, saving on fertilizer costs and reducing environmental impact.

     Isfet is based on MOS field effect transistor technology. Electrical isolation is achieved by implanting phosphorus as an n dopant in a p wafer, making it possible to integrate multiple ISFETs in an N-well. The sensor region in contact with the medium consists of a metal oxide layer that can either act as a pH sensor or be coated with an ion selective membrane. For each ion to be detected, the ISFET must be coated with an appropriate ion selective membrane.