Periodic Reporting for period 1 - sCENT2 (Micro-Scale Photonic Trace Gas Sensor)
Período documentado: 2024-04-01 hasta 2025-09-30
Accurate and highly selective detection of trace gases at part-per-billion (ppb) concentrations is a critical enabling technology for environmental monitoring, industrial process control and emerging healthcare applications. In particular, large-scale in-situ monitoring of climate-relevant gases is increasingly required to understand complex environmental systems and to support evidence-based responses to climate change. At present, however, ppb-level sensitivity and high selectivity are achievable only with bulky and costly laboratory instruments, limiting their deployment in field environments and continuous monitoring networks.
The ERC Starting Grant project sCENT addressed this bottleneck by developing a disruptive chip-scale spectroscopic sensor that combines high-end performance with compactness, robustness and low sample consumption. Using a pioneering waveguide design supporting air-like modes, sCENT demonstrated the first miniaturised sensor capable of ppb-level detection, isotope discrimination and long-term stability on a photonic chip, opening the way to distributed, real-world gas monitoring.
Building on this result, the present project aimed to translate the sCENT concept from proof-of-principle towards real-world applicability. The main objectives were (i) the development of an integrated prototype module and (ii) the preparation of a first field-oriented validation through the study of methane emissions from permafrost-associated bacteria.
In parallel, the project addressed key barriers to exploitation through intellectual property management, early market analysis in environmental intelligence and biotechnology, and the definition of a technology roadmap.
The expected impact is to enable a new generation of compact, highly sensitive and selective gas sensors for large-scale environmental monitoring. By reducing size, cost and operational complexity, the project is expected to unlock new applications in climate research, environmental surveillance and industrial diagnostics and to significantly improve our capacity to observe trace-gas dynamics in natural and engineered systems.
The ERC Starting Grant project sCENT addressed this bottleneck by developing a disruptive chip-scale spectroscopic sensor that combines high-end performance with compactness, robustness and low sample consumption. Using a pioneering waveguide design supporting air-like modes, sCENT demonstrated the first miniaturised sensor capable of ppb-level detection, isotope discrimination and long-term stability on a photonic chip, opening the way to distributed, real-world gas monitoring.
Building on this result, the present project aimed to translate the sCENT concept from proof-of-principle towards real-world applicability. The main objectives were (i) the development of an integrated prototype module and (ii) the preparation of a first field-oriented validation through the study of methane emissions from permafrost-associated bacteria.
In parallel, the project addressed key barriers to exploitation through intellectual property management, early market analysis in environmental intelligence and biotechnology, and the definition of a technology roadmap.
The expected impact is to enable a new generation of compact, highly sensitive and selective gas sensors for large-scale environmental monitoring. By reducing size, cost and operational complexity, the project is expected to unlock new applications in climate research, environmental surveillance and industrial diagnostics and to significantly improve our capacity to observe trace-gas dynamics in natural and engineered systems.
During the project, the main technical activities focused on the integration, validation and performance assessment of the sCENT chip-scale spectroscopic sensor towards a prototype-level implementation.
A first major achievement was the demonstration of direct laser-to-chip coupling without intermediate bulk optics. A custom-packaged interband cascade laser was mounted in an open TO-66 package with the laser facet protruding to enable sub-micrometre alignment. A setup combining nanopositioners and a mid-infrared camera was developed to optimise the coupling between the laser and the sensor chip. Direct coupling was achieved with transmitted spectral power and lineshape essentially identical to those obtained using conventional lens-based coupling. This experiment addressed the highest technical risk of the project, namely that coupling losses or optical feedback could degrade the spectroscopic performance. These risks did not materialise, demonstrating the feasibility of a compact, optics-free sensor architecture.
A second key activity concerned the investigation of surface-induced optical losses caused by water monolayers on the sensor waveguides. Systematic experiments revealed a strong increase in propagation losses, reaching tens of dB/cm at wavelengths around 3.3 μm, critical for methane detection. This effect represents a major limitation for operation in ambient atmospheres. A dedicated study quantified the impact of water adsorption and developed mitigation strategies. Fluorinated surface passivation significantly reduced the additional losses. At wavelengths around 4.35 μm, relevant for CO2 isotope detection, the residual effect after passivation was reduced to fractions of a dB/cm, indicating compatibility with low-loss operation and field deployment. These results constitute original scientific data currently being prepared for publication.
In parallel, prototype assembly activities were initiated to progress towards an integrated sensor module. A micro-assembly bench was installed to support mechanical and electrical integration. Glass-based microfluidic cells (2–20 μL) were designed and fabricated using CO2 laser engraving and indium wire sealing to achieve hermetic bonding to the sensor chip. The complete module architecture was designed and fabrication of all components initiated. Final assembly is planned for early 2026, supported by follow-on funding, with subsequent steps towards automated assembly in collaboration with Tampere University.
By the end of the project, the main outcomes include: (i) the first experimental validation of direct laser–chip coupling for mid-infrared spectroscopic sensing without bulk optics; (ii) the identification and mitigation of a critical surface-loss mechanism limiting open-air operation; and (iii) the design and partial fabrication of an integrated prototype module combining photonic, laser and microfluidic components.
A first major achievement was the demonstration of direct laser-to-chip coupling without intermediate bulk optics. A custom-packaged interband cascade laser was mounted in an open TO-66 package with the laser facet protruding to enable sub-micrometre alignment. A setup combining nanopositioners and a mid-infrared camera was developed to optimise the coupling between the laser and the sensor chip. Direct coupling was achieved with transmitted spectral power and lineshape essentially identical to those obtained using conventional lens-based coupling. This experiment addressed the highest technical risk of the project, namely that coupling losses or optical feedback could degrade the spectroscopic performance. These risks did not materialise, demonstrating the feasibility of a compact, optics-free sensor architecture.
A second key activity concerned the investigation of surface-induced optical losses caused by water monolayers on the sensor waveguides. Systematic experiments revealed a strong increase in propagation losses, reaching tens of dB/cm at wavelengths around 3.3 μm, critical for methane detection. This effect represents a major limitation for operation in ambient atmospheres. A dedicated study quantified the impact of water adsorption and developed mitigation strategies. Fluorinated surface passivation significantly reduced the additional losses. At wavelengths around 4.35 μm, relevant for CO2 isotope detection, the residual effect after passivation was reduced to fractions of a dB/cm, indicating compatibility with low-loss operation and field deployment. These results constitute original scientific data currently being prepared for publication.
In parallel, prototype assembly activities were initiated to progress towards an integrated sensor module. A micro-assembly bench was installed to support mechanical and electrical integration. Glass-based microfluidic cells (2–20 μL) were designed and fabricated using CO2 laser engraving and indium wire sealing to achieve hermetic bonding to the sensor chip. The complete module architecture was designed and fabrication of all components initiated. Final assembly is planned for early 2026, supported by follow-on funding, with subsequent steps towards automated assembly in collaboration with Tampere University.
By the end of the project, the main outcomes include: (i) the first experimental validation of direct laser–chip coupling for mid-infrared spectroscopic sensing without bulk optics; (ii) the identification and mitigation of a critical surface-loss mechanism limiting open-air operation; and (iii) the design and partial fabrication of an integrated prototype module combining photonic, laser and microfluidic components.
The project has delivered several results that go beyond the current state of the art in chip-scale spectroscopic gas sensing and establish a new technological basis for compact, high-performance sensors.
A first major advance is the demonstration of direct laser-to-chip coupling without intermediate optics. In contrast to existing miniaturised spectroscopic systems relying on discrete optical components, the present approach preserves high-resolution, ppb-level performance in a tightly integrated, optics-free architecture, enabling mechanically robust, ultra-compact sensor modules suitable for field deployment.
A second key result is the identification and mitigation of strong absorption losses induced by water monolayers on mid-infrared waveguides, a previously unrecognised limitation for operation in ambient environments. The systematic characterisation of this effect and the demonstration of effective surface passivation provide both new fundamental insight and a practical pathway towards low-loss operation, in particular at wavelengths relevant for CO2 isotope analysis and, with further optimisation, for methane detection.
The development of an integrated microfluidic–photonic prototype module further advances the technological readiness of the sCENT concept by bridging the gap between laboratory demonstrations and deployable sensing devices. The combination of microlitre-scale sampling volumes with high-sensitivity on-chip spectroscopy enables analytical capabilities not accessible with current commercial systems.
Further engineering is required to finalise the prototype assembly, automate packaging and ensure long-term stability. Additional surface-engineering research will further improve performance at methane wavelengths. The prototype has been developed in close interaction with collaborators in arctic marine biology and will be deployed for monitoring bacterial metabolic processes by summer 2026.
Follow-on financing has been secured to complete the current prototype stage. To support scale-up, pilot manufacturing, regulatory qualification and the launch of a spin-off, an application to the EIC Transition programme is planned for autumn 2026, providing the resources and industrial partnerships needed to translate these results into a new generation of compact, high-selectivity spectroscopic gas sensors with broad environmental and industrial impact.
A first major advance is the demonstration of direct laser-to-chip coupling without intermediate optics. In contrast to existing miniaturised spectroscopic systems relying on discrete optical components, the present approach preserves high-resolution, ppb-level performance in a tightly integrated, optics-free architecture, enabling mechanically robust, ultra-compact sensor modules suitable for field deployment.
A second key result is the identification and mitigation of strong absorption losses induced by water monolayers on mid-infrared waveguides, a previously unrecognised limitation for operation in ambient environments. The systematic characterisation of this effect and the demonstration of effective surface passivation provide both new fundamental insight and a practical pathway towards low-loss operation, in particular at wavelengths relevant for CO2 isotope analysis and, with further optimisation, for methane detection.
The development of an integrated microfluidic–photonic prototype module further advances the technological readiness of the sCENT concept by bridging the gap between laboratory demonstrations and deployable sensing devices. The combination of microlitre-scale sampling volumes with high-sensitivity on-chip spectroscopy enables analytical capabilities not accessible with current commercial systems.
Further engineering is required to finalise the prototype assembly, automate packaging and ensure long-term stability. Additional surface-engineering research will further improve performance at methane wavelengths. The prototype has been developed in close interaction with collaborators in arctic marine biology and will be deployed for monitoring bacterial metabolic processes by summer 2026.
Follow-on financing has been secured to complete the current prototype stage. To support scale-up, pilot manufacturing, regulatory qualification and the launch of a spin-off, an application to the EIC Transition programme is planned for autumn 2026, providing the resources and industrial partnerships needed to translate these results into a new generation of compact, high-selectivity spectroscopic gas sensors with broad environmental and industrial impact.