Drone-mounted sensor system for the determination of nitrite and nitrate content in open waters

• Applicant: Professorin Dr. Martina Gerken
• Subject Area: Measurement Systems ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541033675

The spatially resolved determination of nitrite and nitrate content in flowing waters plays an important role in the analysis of nutrient loads to achieve environmental protection goals. Up to now, sampling has mainly been carried out manually or by permanently installed measuring stations. Here, a mobile, drone-based measurement system for quantitative measurement of nitrite and nitrate content in flowing waters will be explored. Compared to manual sampling, drone-based measurement offers the important advantages that larger areas of the water body can be covered in a given time, that sampling can also take place at low water levels and that remote areas can be reached quickly. In addition, the measurement results are directly available and can be used for planning further sampling. In this project, the colorimetric measurement principle of evaluating a color change after a chemical reaction of the water sample will be used. By flying along measurement standards, this measurement principle enables the correction of interferences caused by environmental and drone influences. Based on the current state of research and our own preliminary work, two different system approaches are to be researched and set up as demonstrators for proof-of-concept experiments. Both systems shall be designed for a drone with 5 kg payload. On the one hand, a valve-based microfluidic lab on a chip for colorimetric nitrite and nitrate measurements with a measurement duration of 5 minutes shall be developed. This will enable local measurements at different positions in the flowing water. For sampling, the drone will be lowered to a flight altitude of 1 m at each location and the sample will be taken with a tube. As a second system, a droplet-based microfluidic lab on a chip will be explored, which allows a drag-along operation of the tube immersed in the water for a high spatial resolution. Here, a duration of only 12 seconds per measurement is targeted. For both systems, the on-board data acquisition, signal processing and communication will be designed to be energy efficient. Accompanying the experimental work, a detailed model of the measurement approaches will be developed that allows the prediction of the measured values and measurement uncertainties of the nitrite and nitrate measurements as a function of the resources weight, energy, volume, and time per measurement. Factors that generate cross influences and affect the measurement uncertainty, such as vibrations in the flying measurement platform, will be investigated in detail. The model will be validated with open field experiments at the Füsinger Au in the model region Schlei against manually taken samples. The aim of the project is to develop the measurement principle of colorimetric measurement of nitrate and nitrite with a microfluidic lab on a chip for flying measurement platforms.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2433: Metrology on flying platforms