Progress summary
Between months 19 and 36, the M3NIR project achieved substantial progress in the development of its mid-infrared sensing platform. Key advancements include the refinement of quantum cascade laser (QCL) sources, fabrication and integration of scalable Ge-on-SOI photonic integrated circuits (PICs), validation of passive Ge-on-Si components, and the development of new sensing modules that operate effectively in environmental, liquid, and breath analysis applications. Additionally, improvements in microfluidic systems, electronics, and data acquisition platforms have enabled miniaturized, portable, and high-performance sensors suitable for various critical applications, aligning with European strategic goals.
Key obtained results
During this period, the project marked notable progress across all technical work packages. Multiple batches of QCL chips were fabricated and assembled, focusing on increasing power stability and spectral purity. Several hybrid integration processes were successfully demonstrated, leading to optically coupled QCLs with initial output powers around 1.25 mW, with ongoing process refinements planned to enhance performance at room temperature. Efforts to develop flip-chip compatible QC chips have progressed, although further optimization is necessary to overcome power limitations identified during initial fabrication.
On the photonic platform side, the fabrication of Ge-on-SOI PIC components has reached a level of maturity. Several devices, including waveguides, multimode interferometers (MMIs), and wavelength-selective filters, have been fabricated and characterized, confirming low optical losses and consistency across production batches. These passive components have been successfully integrated with microfluidic modules, facilitating liquid sensing with leak-proof operation and miniaturized design.
Active PICs incorporating on-chip heaters, beam combiners, and distributed Bragg reflectors (DBRs) have been designed and tested. Preliminary active tuning experiments have exhibited satisfactory control over emission wavelengths, demonstrating that the integration of active elements is feasible and promising for multi-gas detection. The active alignment and hybrid integration of QCL sources onto these PICs are advancing, with initial measurements indicating stable coupling.
The self-mixing detection technique, which enables detector-less sensing by measuring laser terminal voltage variations, has been further developed and validated in laboratory settings. Experiments measuring gases such as ammonium and breath-relevant CO2 isotopologues show that the system can achieve limits of detection comparable to standard FTIR methods, with promising robustness for real-world applications. The microfluidics development has resulted in portable, leak-proof chips with integration solutions tailored for liquid handling and sample exchange, allowing flexible operation in field conditions.
Electronics development has yielded low-power, portable laser and TEC driving modules, significantly reducing power consumption relative to laboratory bench systems. These electronics are now capable of supporting field deployment, including integration into mobile platforms like drones. The data acquisition and analysis platform, built as a secure cloud-based system, has been extended with visualization dashboards, machine learning algorithms, and synthetic data generation capabilities, enabling efficient data processing, trend analysis, and real-time monitoring.
In the context of use cases, the system has been tested and validated in controlled laboratory conditions. For environmental sensing, prototype drone-mounted sensors capable of detecting greenhouse gases have been constructed. Initial field trials demonstrate potential deployment for environmental monitoring aligned with Green Deal objectives. For liquids analysis, microfluidic channels integrated with Ge PICs have been used to measure ammonium concentrations, showing linear responses and detection capabilities within regulatory limits. In exhaled breath analysis, calibration experiments with integrated QCL-iHWG modules have successfully measured isotopic CO2 ratios, demonstrating the potential for non-invasive health diagnostics.
In sum, the project’s advancements during months 19–36 have considerably matured the core sensing techniques and system integration, moving closer toward operational prototypes suitable for real-world applications in environmental, health, and industrial sectors.
