Within the framework of the CitizenSensor project, Fraunhofer EMFT and FabLab Munich have developed a nitrate measuring kit for amateur gardeners.

A key factor in domestic horticulture is the nitrate in the soil: too low a concentration inhibits plant growth; too high a concentration pollutes the environment and the food grown. The measurement kit – based on electrochemical sensor technology and developed by Fraunhofer EMFT and FabLab Munich in a Co-Creation approach – enables nitrate measurements at a professional level even without expensive equipment and expertise.

The system detects nitrate concentrations of up to 4 mg/L. For measurement, an electrode coated with an ion-selective membrane for nitrate is immersed in a solution together with an Ag/AgCl reference electrode, and the voltage between the electrodes is measured. Environmental parameters such as air pressure, temperature, and humidity are recorded by the device automatically.

Thanks to its low power consumption, the mobile laboratory is suitable for use in the field – in the truest sense of the word. Only a saline solution is required for calibration, which can be easily prepared using the integrated weighing scales. Web-based step-by-step instructions enable people without specialist knowledge to take the correct samples, document the measurement results, and automatically check them for plausibility.

The development team is currently testing its device for practical suitability together with urban gardening initiatives in Munich.

The project is being funded by Germany’s Federal Ministry of Education and Research (BMBF) under funding code 01BF1711B.