Fraunhofer miniaturises ISFET-based pH sensor control

The Fraunhofer Institute for Photonic Microsystems (IPMS) has successfully miniaturized the electronics needed to control ion-sensitive field-effect transistors (ISFET), resulting in reduced manufacturing costs and power consumption. The new electronics are now available for direct use or integration into in-house measuring systems. This development comes after the creation of niobium pentoxide-based ISFET pH sensors, which enable the continuous and precise measurement of pH values by analyzing the concentration of specific ions in water or other aqueous media in real-time.

Dr. Olaf R. Hild, Head of the business unit Chemical Sensors at Fraunhofer IPMS, expressed satisfaction with the progress, stating, “After almost one year of development, we have successfully controlled our Nb2O5-ISFETs to measure continuously with a power consumption of less than 1.3 mW, including electronics.” The power consumption of the sensor system has been reduced to only 190 µW, making it ideal for mobile measuring systems where power consumption and size are crucial factors.

The applications of this technology extend to continuous water monitoring and environmental analysis. Moreover, there is potential for long-term use in medical technology, particularly in analyzing various body fluids, necessitating small yet high-performance measuring systems.

The new control electronics, set to be unveiled at the “Sensor and Test” trade fair in Nuremberg this May, are characterized by their low power consumption and energy efficiency. They are user-friendly and ready for immediate deployment. The system comprises analogue electronics consuming less than 1.3 mW and digital electronics that can be connected via USB-C at around 100 mW, enabling quick on-site calibration.

Hans-Georg Dallmann, an electronics developer, highlighted the exceptional stability and accuracy of the Fraunhofer IPMS ISFETs, stating, “As the ISFETs exhibit extremely low drift and almost perfect Nernst dependence, a single-point calibration suffices for the majority of applications, ensuring high accuracy even over extended periods.” The focus now shifts towards further miniaturization, with plans to develop ISFET chips under one-millimeter square to cater to size-constrained applications.