Enhanced Raman-spectroscopic multi-gas-sensing on an airborne platform/unmanned aerial vehicle for 3D-mapping of concentrations

• Applicant: Professor Dr. Torsten Frosch
• Subject Area: Measurement Systems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541022478

Gas measurements on drones are becoming increasingly important. In contrast to ground-, tower-, airplane- or satellite-based measurement systems, drones enable the flexible monitoring of air in the vicinity of buildings and ecosystems. Independent of further infrastructure, gas concentrations can thus be mapped with high resolution. However, it is not possible to measure complex multigases with current sensor technology that is suitable for the use on drones. Consequently, currently only selected individual gases are detected or quantified. We aim to close this gap in sensing technology by developing a miniaturized measurement system based on enhanced Raman gas spectroscopy (RGS) and deploying it on a drone. When deployed on a drone, RGS would have the advantage of enabling exploratory measurements without a priori knowledge, simultaneously detecting and quantifying all gases (except noble gases) and volatile organic compounds (VOCs). A single flight could thus provide a comprehensive 3D concentration profile of the environment surrounding a building, industrial facility, or small ecosystem. Notably, the RGS is also sensitive to hydrogen, which is of interest for monitoring gas infrastructure (power-to-gas) as well as for studying emissions from thawing permafrost soils. In order to achieve the goal of RGS on drones, we need to overcome two challenges: (1) We need to highly miniaturize the Raman gas analyzer (RGA) to meet the constraints on size, weight, and power consumption on a drone. (2) Also in the miniaturized RGA, a sophisticated enhancement mechanism has to be applied to enable sensitive measurements despite the weak Raman signals from gases. In this research project, we aim to build a fully miniaturized, highly sensitive measurement system for use on a drone based on our expertise in fiber-enhanced RGS. Our goals are: 1) Development of a miniaturized RGA including a unit for signal enhancement, 2) Development of methods to correct for perturbations (environmental and from the drone), as well as energy-efficient data processing solutions, 3) Integration of the miniaturized RGA on a drone, 4) Measurements in the open field: exploratory measurements of the air in the vicinity of ecosystems and facilities. In order to achieve these goals, we will combine fiber-enhanced RGS with new approaches to miniaturize Raman spectroscopic instruments (WP1 and WP2). We will also characterize the fidelity of quantitative measurements with measurement uncertainties and address data processing and communication (WP3 and WP4). The miniaturized and extensively characterized RGA will then be integrated and tested on a drone (WP5) and finally deployed in free-field measurements (WP6).

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