Periodic Reporting for period 1 - SWISSMODICS (Development of a Sensor with WIde Spectrum Sensitivity for MOnitoring of Damage and Defects In Composite Structures)
Okres sprawozdawczy: 2020-07-01 do 2021-12-31
In SWISSMODICS, an EU-funded Clean Sky project coordinated by CSEM, experts will develop an image sensor that can be incorporated into an aircraft’s composite structure in order to detect damage and defects. The device will make aircraft inspections considerably simpler, thereby avoiding the need for extended downtime or disassembly.
Aircraft are inspected regularly, during routine maintenance and also after their structure has experienced an impact that may have been caused by ground support equipment at the airport gate, for example, or an in-flight collision with birds. Importantly, the damage caused by the impact doesn’t always occur exactly where the structure was hit. That’s especially true for aircraft made from composite materials, which are increasingly common as composites weigh less than conventional materials. “When a composite material is impacted, that creates a shock wave that propagates through the material and may cause damage – called delamination – at a point away from the original impact,” says Pierre-François Rüedi, the CSEM expert who’s heading up the project. “This makes the damage harder to detect.”
A variety of methods are available for detecting delamination in composites. However, they involve inspections that require aircraft to be grounded for long periods of time or even disassembled – both of which are costly processes.
In SWISSMODICS, three partner organizations – CSEM, Jean Monnet University in Saint-Etienne, France, and Almay Technologies in Chauvigny, France, – will develop a thin (<1 mm thick) broad-wavelength-spectrum image sensor that can be incorporated directly into an aircraft’s composite structure in order to detect damage. The Topic Manager Airbus is interested in this new technology as it could substantially shorten inspection times and reduce the inconvenience caused to both airlines and passengers, especially when planes must be grounded at the last minute for unplanned maintenance inspections.
An imager sensitive to visible, X-ray and infrared wavelengths
The new device will be designed to detect a broad spectrum of wavelengths: visible (i.e. those that can be seen with the naked eye), X-ray (used in medical imaging, for example) and infrared (used most notably in thermal detection systems). Operators will therefore be able to choose from these three different ranges and select the one that’s most effective for the type of damage they want to detect or the area they want to inspect. “In addition to helping aircraft owners avoid downtime and conduct more frequent, faster inspections, our technology will deliver a range of sensitivity that no other system currently out there can provide,” says Rüedi.
Sensitive layers optimized for specific wavelengths
The sensor will include an electronic chip on which different types of sensitive layers have been deposited, each one capable of detecting a different wavelength. The exact composition of the layers will depend on the wavelength being targeted, but they will all have one thing in common: they will be made primarily from perovskite, a semiconducting material that’s also used in solar cells. The light captured by the layers will then be processed by the chip.
CSEM will be in charge of developing the chip and studying the layer composition, in association with researchers at Jean Monnet University, who will characterize the components. Almay Technologies, which is specialized in composites for aeronautical applications, will test the new device on composite structures with defects. The project, scheduled to be completed in August 2023, should support the development of lighter aircraft, with all the environmental benefits that will bring.
Aircraft are inspected regularly, during routine maintenance and also after their structure has experienced an impact that may have been caused by ground support equipment at the airport gate, for example, or an in-flight collision with birds. Importantly, the damage caused by the impact doesn’t always occur exactly where the structure was hit. That’s especially true for aircraft made from composite materials, which are increasingly common as composites weigh less than conventional materials. “When a composite material is impacted, that creates a shock wave that propagates through the material and may cause damage – called delamination – at a point away from the original impact,” says Pierre-François Rüedi, the CSEM expert who’s heading up the project. “This makes the damage harder to detect.”
A variety of methods are available for detecting delamination in composites. However, they involve inspections that require aircraft to be grounded for long periods of time or even disassembled – both of which are costly processes.
In SWISSMODICS, three partner organizations – CSEM, Jean Monnet University in Saint-Etienne, France, and Almay Technologies in Chauvigny, France, – will develop a thin (<1 mm thick) broad-wavelength-spectrum image sensor that can be incorporated directly into an aircraft’s composite structure in order to detect damage. The Topic Manager Airbus is interested in this new technology as it could substantially shorten inspection times and reduce the inconvenience caused to both airlines and passengers, especially when planes must be grounded at the last minute for unplanned maintenance inspections.
An imager sensitive to visible, X-ray and infrared wavelengths
The new device will be designed to detect a broad spectrum of wavelengths: visible (i.e. those that can be seen with the naked eye), X-ray (used in medical imaging, for example) and infrared (used most notably in thermal detection systems). Operators will therefore be able to choose from these three different ranges and select the one that’s most effective for the type of damage they want to detect or the area they want to inspect. “In addition to helping aircraft owners avoid downtime and conduct more frequent, faster inspections, our technology will deliver a range of sensitivity that no other system currently out there can provide,” says Rüedi.
Sensitive layers optimized for specific wavelengths
The sensor will include an electronic chip on which different types of sensitive layers have been deposited, each one capable of detecting a different wavelength. The exact composition of the layers will depend on the wavelength being targeted, but they will all have one thing in common: they will be made primarily from perovskite, a semiconducting material that’s also used in solar cells. The light captured by the layers will then be processed by the chip.
CSEM will be in charge of developing the chip and studying the layer composition, in association with researchers at Jean Monnet University, who will characterize the components. Almay Technologies, which is specialized in composites for aeronautical applications, will test the new device on composite structures with defects. The project, scheduled to be completed in August 2023, should support the development of lighter aircraft, with all the environmental benefits that will bring.
Two different sensing technologies for infrared sensing have been evaluated. The first one is based on sol-gel with appropriate composition to perform up conversion of near-infrared photons to visible photons, which can then be detected by an image sensor. The second technology evaluated is based on perovskite materials optimized to detect near-infrared light. Here, near-infrared photons directly generate charges in the perovskite material, leading to a direct conversion from photons to charges. UJM demonstrated up-conversion of 980 nm photons to green photons in the sol-gel material, and CSEM developed perovskite material with a quantum efficiency above 40 % at 950 nm. The outcome of the evaluation led to the selection of perovskite as the chosen sensing material for the sensor.
The sensitivity of perovskite cells to X-ray has been characterized by UJM, showing a linear response to the dose rate for over more than 4 decades. Furthermore, no degradation of the sensitivity was observed after a total ionization dose of 55 kGy.
Methods to pattern the different perovskite materials on top of a pixelated readout chip have been investigated.
Composite samples incorporating faults such as delaminations have been produced, to be tested first with commercial X-ray and near-infrared imaging equipment, which will serve as a reference to characterize the performance of the sensor to be developed within the SWISSMODICS project.
Specifications of the sensor and system have been established, and the design of the sensor chip has started.
The sensitivity of perovskite cells to X-ray has been characterized by UJM, showing a linear response to the dose rate for over more than 4 decades. Furthermore, no degradation of the sensitivity was observed after a total ionization dose of 55 kGy.
Methods to pattern the different perovskite materials on top of a pixelated readout chip have been investigated.
Composite samples incorporating faults such as delaminations have been produced, to be tested first with commercial X-ray and near-infrared imaging equipment, which will serve as a reference to characterize the performance of the sensor to be developed within the SWISSMODICS project.
Specifications of the sensor and system have been established, and the design of the sensor chip has started.
The SWISSMODICS consortium will deliver an ultra-thin sensor module containing an image sensor sensitive to X-ray, near-infrared and visible light, based on perovskite layers deposited on top of a readout chip. Demonstrated on a composite panel incorporating faults such as delaminations, it will be a first step toward the integration of imaging sensors within the airframe structure. This technology will ease structural monitoring of airplanes reducing immobilization time and enabling more frequent monitoring of critical parts. It can be used for non-destructive testing and structural monitoring outside of the aeronautical field. However, its application is not limited to non-destructive testing. The perovskite material used is a very good X-ray absorber, enabling to minimize the irradiation dose. This is of paramount importance in the medical field, where this technology offers very interesting perspectives. Furthermore, perovskite can also be optimized for ultra-violet, enabling the development of multispectral imagers covering the ultra-violet to near-infrared spectrum.