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FLying ultrA-broadband single-shot InfraRed sensor

Periodic Reporting for period 2 - FLAIR (FLying ultrA-broadband single-shot InfraRed sensor)

Reporting period: 2018-05-01 to 2020-12-31

Today, significant effort is devoted to improve air quality through land-use planning strategies, replacement of fossil fuels by clean energy sources and lower level of industrial emission. In order to be successful, these measures need be accompanied by air quality monitoring at large scale to ensure compliance with air quality legislation but also to provide information for political decision making regarding air quality and safety. This is particularly challenging outside the dense urban network of air quality monitoring stations. FLAIR aims to mount a high-performance air-sampling sensor based on cutting-edge photonic technology on an airborne platform for pervasive and large area coverage high-specificity and high-sensitivity (ppbv) air quality sensing. Operating in the two atmospheric windows of 2-5 µm and 8-12 µm wavelength, FLAIR can detect minute traces of molecules in complex gas mixtures from their characteristic IR absorption fingerprints and provide real time information to the operator. FLAIR can operate in remote or dangerous areas and outside of established monitoring networks: around industrial infrastructure, highways and ships or in case of catastrophic events like wildfires, volcanic eruption or chemical accidents.

Two sensors were developed, the first sensor aims for a cost effective, compact, lightweight, sensitive, selective and real-time molecular trace gas detector. The sensor has been tested on-board a flying helicopter and zeppelin with well-defined validation test settings. The second sensor provides an ultra-broad spectral coverage (2-11 µm) and 1 GHz spectral resolution, for selective and sensitive multispecies trace gas detection.
In the initial stage, the Consortium defined qualitative and quantitative requirements for the sensor and the airborne platform. Laboratory spectroscopy was performed, to achieve important baseline knowledge regarding the defined relevant gas species.

The development of the sensor itself comprised of the development of each subsystem and integration into a prototype and its testing. Consortium member NKT provided a short wavelength supercontinuum source for CSEM and RU, for laboratory tests. In addition, a highly compact version of this source was developed and for integration into the finalized prototype at CSEM. The longer wavelength source was designed and development by DTU. RU develop a lab based transportable spectrometer based on the expected specifications of the long wavelength supercontinuum source and validated the source in laboratory conditions.

SA developed a customized low-cost mass-producible multipass cell using a new molding technology. NIT developed a specific uncooled infrared camera. CSEM took care about the data processing algorithms, to extract the concentration of different species from the camera image. In addition, CSEM developed a gas handling system and a power distribution electronic board for the different components of the sensor. For control, a powerful mini PC is used. All components were integrated into the final sensor prototype at CSEM.

For validation, the sensor instrument was evaluated with calibration gases and compared to a calibrated reference instrument at EMPA. The first flying test was performed by CSEM and EMPA at the airfield in Beromünster (CH). The instrument was mounted on a zeppelin and operated during a test flight. Methane was released in a controlled way from a gas cylinder for simulating a significant methane source. As such, the capabilities of the FLAIR instrument for detecting elevated methane concentration were successfully demonstrated. A second flying test was performed in Denmark on a helicopter, by CSEM and the company Explicit. A 3-days flight campaign allowed for observation of 123 ship plumes. Comparison with established technology used by Explicit was successful, and ships with strongly elevated methane emissions were observed. Generally, the enhanced methane concentrations were attributed to liquid natural gas (LNG) engines. This campaign confirmed that the FLAIR sensor could successfully operate on airborne platforms, such as a helicopter.

The communication and outreach aimed for raising awareness of FLAIR objectives, concept and approach. The project webpage and social media page(s) were initiated, keeping the audience updated about the project progress and its results. A newsletter was published on a regular basis and disseminated via the web portal, e-mail subscriptions, conferences, exhibitions and workshops. All members published scientific and academic papers and posters; presenting the FLAIR instrument as a whole and/or its corresponding subsystems. Partner SA has made two series of promotional videos on the FLAIR project for the general audiences.

The Consortium delivered a highly innovative instrument representing a breakthrough in broadband infrared spectroscopy, for better and pervasive environmental sensing, contributing towards securing and reinforcing industrial European leadership in sensing applications.

NKT will generate new markets for the mid-IR supercontinuum sources and strengthen other markets. The low-cost source is interesting for sensing exhaust gases from combustion processes to optimize engine efficiency and minimizing emission. SA and NKT will further develop the sensor system for the chemical or bioreactor industries, where continuous monitoring of chemical compositions is necessary to optimize production. More complex systems, combining IR spectral information with imaging technology, can allow medical diagnostic and sorting of raw materials. NIT, with their unique uncooled focal plane detectors, will extend the marked from imaging applications into infrared spectroscopy.

Built on the successful implementation of the FLAIR project, several members joint the Horizon 2020 project: “Ultra-broadband infrared gas sensor for pollution detection”. Its goal is to develop a smart, compact and cost-effective, air-quality sensor network for the hyperspectral detection of relevant atmospheric pollution gases.
The progress beyond state-of-the-art covers the sensor as a whole, at system level and subsystem level. The FLAIR solution presents an encouraging compromise between cost effectiveness, performance and footprint. Although, the targeted selectivity and sensitivity are not as high as those obtained with mass spectrometry, the latter is limited by its footprint and complexity.  Electronic noses are commercially available at reasonable prices, but suffer from low accuracy, resolution and selectivity. FTIR spectrometers combine cost-effectiveness with high resolution, but are not suited for flying operation. Other photonic-based systems in the infrared have enabled highly sensitive and selective detection of molecules. However, those solutions typically remain confined to research labs due to their narrow spectral operating window (covering only very few molecules), their complexity and prohibitively high cost.

At the subsystem level, progress beyond state-of-the-art is reached, attributable to the uncooled monolithically integrated infrared camera, the supercontinuum source reaching out into the mid-infrared (10 µm), and a low-cost mass-producible multipass cell.
FLAIR - an airborne, high-performance air sampling sensor based on cutting-edge photonic technology