Indirect photothermal infrared spectroscopy of dense materials typically relies on photoacoustic cells for detecting acoustic waves generated by light-induced heating. This detection approach can be challenging to implement as it is highly sensitive to the sealing quality of the interface between the cavity and the sample, as well as to the properties of the gas within the cavity. Here, we present a simplified and more robust method. This approach relies on direct photothermal temperature measurement using an optimized platinum microsensor fabricated on a thin silicon substrate that acts as a thermally transparent interface with the sample. The sensor design, fabrication in a 200 mm CMOS pilot line, assembly on a readout PCB, and experimental characterization are reported. The component achieves a signal-to-noise ratio close to 1000 making it well-suited for miniaturized and embedded infrared spectroscopic applications.

We report on a hybrid III-V/Si quantum cascade laser based on external silicon distributed Bragg reflector (Si-DBR) cavity mirrors, operating around 4.5 µm under pulsed excitation. In this architecture, the III-V section provides optical gain, while the wavelength-selective feedback is defined by Si-DBR mirrors located outside the active region. Adiabatic silicon tapers are used to couple the optical mode between the III-V ridge and the DBR mirrors, enabling spatial separation between the gain medium and the feedback elements. The device exhibits single-mode emission at 4.497 µm from threshold to rollover, with a threshold current density of 5.8 kA·cm⁻² and a maximum estimated peak power of 340 µW in the silicon waveguide at 12 °C. Stable pulsed operation is obtained up to 52 °C, with a characteristic temperature of 179 K. This demonstration validates an alternative hybrid quantum cascade laser (QCL) architecture in which the laser cavity feedback is defined by silicon DBR mirrors, opening a route toward more flexible mirror engineering, asymmetric output coupling and fine wavelength tuning through active modulation of the DBR sections.

This paper aims to propose and discuss a pathway to versatile, portable, and wearable photonics devices in the mid-infrared region. We address the benefits and challenges of mid-infrared spectroscopy in the fingerprint region and the development of low-cost mass production devices for real-world applications in the near future. Firstly, the paper briefly introduces the mid-infrared and fingerprint region and discusses the importance of the detection of mid-infrared biomarkers for point-of-care medical applications, stressing the importance of multi-wavelength probing systems. We also discuss the challenge of long-wavelength signals through the matter and the benefits of photo-acoustic detection. The pathway we envisage is twofold: the first is to improve and predict deviation from the standard Bouguer-Beer-Lambert approximation for light propagation in tissue and matter. This approach requires calibrated and wavelength-specific sources. Secondly, to address these requirements, the paper presents the potential for future low-cost personalized devices based on an array of quantum cascade lasers developed on low-cost C-MOS technology and using photo-acoustic detection. The technology was first developed for gas analyses, but we report on a recent successful wearable device for glucose monitoring, which passed clinical trials. This technology will allow the development of future widespread portable mid-infrared devices with potential application not only in healthcare, addressed here, but also in precise gas and environmental chemical monitoring. The ability to record mid-infrared biomarkers at the point of care will be fundamental for the personalized optical digital twin, which will be the cornerstone of future healthcare systems.

The increasing demand for mid-infrared (MIR) photonic integrated devices in spectroscopic applications has driven the development of essential building blocks for chemical sensing, including quantum cascade lasers (QCLs), MIR silicon photonic platforms and integrated detectors. A fully integrated MIR silicon photonic chip would enable cost-effective mass production using CMOS-compatible fabrication, paving the way for consumer-grade MIR devices and large-scale onsite sensing applications. However, the integration of QCLs with MIR silicon platforms remains a major challenge due to inefficient optical coupling between the III-V active region and silicon waveguides, leading to high insertion losses and reduced device performance. In this work, we demonstrate the heterogeneous integration of a QCL onto a believed to be novel high-index-contrast, phase-matched silicon on nitride on insulator (SONOI) photonic platform using molecular bonding. By leveraging a phase-matching condition, we implement an adiabatic coupling scheme that ensures efficient optical power transfer from the III-V active region to the silicon waveguides, overcoming a key limitation of previous approaches. The resulting hybrid distributed-feedback (DFB) QCL exhibits single-mode emission at 4.315 µm and operates in pulsed mode up to 72 °C. This advancement opens new possibilities for fully integrated MIR photonic circuits, with potential applications in environmental monitoring, biomedical diagnostics, and industrial sensing.

Gas chromatography is a reference method for gas analysis. As part of efforts to miniaturize gas chromatography systems, the miniaturization of detectors is essential. In this work, we report a new integrated photonic platform for gas chromatography analyte detection. The fabricated silicon die integrates Mach-Zehnder interferometers into low dead volume microfluidic channels, with coherent cost-effective detection scheme with a fixed 850 nm wavelength laser. A proof of concept is demonstrated with the separation and detection of three volatile organic compounds: heptane, octane, and toluene. Peaks' widths at half height range from 1 to 5 s. Peaks are very well resolved by our system, which acquires more than 100 points per second. From a heptane dilution range, we evaluate the limit of detection of our system to be the headspace of a 0.26 % heptane concentration solution. To our knowledge, these are the first integrated Mach-Zehnder interferometers reported for gas chromatography detection. This work could open new strategies for fast low cost and low limit of detection specific gas chromatography silicon micro-detectors.

Current issues on air pollution monitoring or greenhouse gases emissions rely on the sparse use of expensive gas sensors. We target to develop a portable miniaturized sensor with the capacity of being gas-specific, lightweight and autonomous. We present here results obtained with our newly packaged Photoacoustique Module. We also present the development of its dedicated electronic companion system.

Digital microfluidics platforms (DMFPs) have shown their efficiency in sample handling, using elementary operations that may be combined to perform complex applications. In this article, we present a new platform for gaseous samples handling involving a two-step digital preconcentration using the miniaturized preconcentrators of the DMFP. Choosing n-pentane at very low concentrations as a model for highly volatile compounds, poorly retained on the sorbent, the DMFP allowed bypassing the limit set by the breakthrough volume by repeating an elementary operation. It enabled a 5-fold increase of preconcentration factors in comparison to a single preconcentration step and an easier monitoring of the model compound. Promising applications are expected, as this system could be adapted to most volatile compound analysis devices, including micro gas chromatographs, to replace the current single-step preconcentration systems. By switching to two-step preconcentration with a DMFP, i.e., a digital preconcentration, it would be possible to get more concentrated samples through the column for easier trace analysis.

The first device for digital manipulation of gaseous samples; from elementary operations to demonstration of a more complex application.

Algae production in Europe is currently limited to a few small industries, mainly for the feed, nutrition and cosmetic sectors. This sector is ripe for further expansion. However, creating an economically viable and sustainable method of growing large quantities of algae with consistent quality and converting them into successful commercial products that the markets accept remains an industrial challenge.

A first digital microfluidic system has been fabricated that allows to perform programmable and reconfigurable step by step manipulations of gas and volatile compounds. While digital microfluidic platforms have been extensively reported for the manipulation of droplets, such an approach for gaseous samples have not been proposed so far. The programmable system relies on interconnected temperature controlled silicon chips filled with adsorbent that can trap and release analytes. As a proof of concept, all the key elementary operations are demonstrated with alkanes ranging from n-hexane to n-nonane: the trapping, release, moving, adding (mixing) and subtracting (separating) of gaseous analytes. Following the example of digital microfluidic droplet manipulation, such system could open in the future a new field of technologies and applications regarding gas or volatile compounds samples preparation and analysis.

This work reports on the improved performance using nanoporous organosilicate (SiOCH) for lab-on a-chip extraction of organic pollutants from natural waters. Validations were carried out for polycyclic aromatic hydrocarbons (PAHs) extraction, and the results were compared with the commonly used SBSE laboratory technique (Stir-Bar Sorptive Extraction). While a previous study performed with PDMS coated lab-on-a-chips had showed limitations for the most polar PAHs (log K-ow < 5.5) and real matrices, we demonstrate here that, thanks to the novel phase, there is a good affinity for PAHs, even in natural waters. An improved microfluidic device in term of channel width and chip total area could be selected. Most importantly, the extraction time of 20 min still used with this type of microfluidic device is very short compared to the 24 h needed with the SBSE laboratory technique. Moreover, the high specific surface area of the nanoporous phase reduces the matrix effects related to interferences with dissolved organic matter. Therefore these new porous SiOCH coated extraction microchips appear as a good alternative to PDMS-based extraction techniques such as SBSE and should be used for further development of field analysis devices. (C) 2017 Elsevier B.V. All rights reserved.

This work presents the performances of silicon micro-preconcentrators chips for breath sampling. The silicon chips were coupled to a handheld battery powered system for breath sampling and direct injection in a laboratory gas chromatography mass spectrometry system through thermal desorption (TD). Performances of micro-preconcentrators were first compared to commercial TD for benzene trapping. Similar chromatographic peaks after gas chromatographic separation were observed while the volume of sample needed was reduced by a factor of 5. Repeatability and day to day variability of the micro-preconcentrators were then studied for a 500 ppb synthetic model mixture injected three times a day four days in a row: 8% and 12% were measured respectively. Micro-preconcentrator to micro-preconcentrator variability was not significant compared to day to day variability. In addition, micro-preconcentrators were tested for breath samples collected in Tedlar® bags. Three analyses of the same breath sample displayed relative standard deviations values below 16% for eight of the ten most intense peaks. Finally, the performances of micro-preconcentrators for breath sampling on a single expiration were illustrated with the example of volatile tobacco markers tracking. The signals of three smoking markers in breath, benzene, 2,5-dimethylfuran, and toluene were studied. Concentrations of benzene and toluene were found to be 10 to 100 higher in the breath of smokers. 2,5-dimethylfuran was only found in the breath of smokers. The elimination kinetics of the markers were followed as well during 4 h: a fast decrease of the signal of the three markers in breath was observed 20 min after smoking in good agreement with what is described in the literature. Those results demonstrate the efficiency of silicon chips for breath sampling, compared to the state of the art techniques. Thanks to miniaturization and lower sample volumes needed, micro-preconcentrators could be in the future a key technology towards portable breath sampling and analysis.

Sensor microelectromechanical gas comprising: - a fixed part (2), - at least one sprung part (4) relative to the fixed part (2), - at least one sensitive zone (6) carried by the suspended part (4), said sensitive zone (4) being capable of adsorbing / absorbing and desorbing gaseous species or families of gaseous species, - heating means (8) at least of the sensitive area (6), - detecting means (10) of the adsorption / absorption and desorption of the gaseous species or families of gaseous species on the sensitive zone, - heating means of the control means (8) so that the heating means (8) applied to at least the sensitive area (6) one or more temperature profiles ensuring the adsorption / absorption and desorption of gaseous species controlled manner so as to obtain an individual desorption of each species or families of gaseous species.

In this paper, we report the feasibility of handheld systems that can both sample gas for further laboratory analysis as well as provide first field analysis by gas chromatography. In particular the systems include micro silicon preconcentrator chips that enable concentration of Volatile Organic Compounds (VOCs) by a factor of 1000 for sampling durations smaller than 1 minute, as well as micro silicon thermal conductivity detector with a limit of detection in the parts-per-million level. Regarding sampling, the system developed here is compared to state of the art technique using sorbent tube and thermodesorption: comparable results are obtained on a 500 ppb BTEX (Benzene Toluene Ethylbenzene, Xylene) mixture. Regarding analysis, the separation and detection of VOCs down to 20 ppb is demonstrated, without the need of a carrier gas cylinder. Such systems, compatible with low cost development in the future, could find applications in the consumer market for air pollution monitoring.

This article introduces a joined Bayesian estimation of gas samples issued from a gas chromatography column (GC) coupled with a NEMS sensor based on Giddings Eyring microscopic molecular stochastic model. The posterior distribution is sampled using a Monte Carlo Markov Chain and Gibbs sampling. Parameters are estimated using the posterior mean. This estimation scheme is finally applied on simulated and real datasets using this molecular stochastic forward model.

Preconcentration is an important technological brick as part of the development of gas analysis systems [1,2,3]. We report here on the fabrication of silicon micro-preconcentrators that enable preconcentration of toluene by a factor of 1000 for sampling durations smaller than 1 minute. For a selected design, the toluene peak width at halt height remains similar with and without préconcentration, keeping the system efficiency. The peak width however varies from 0.8s to 6.2s depending on preconcentration chip design. Preconcentration factors greater than 7000 have been obtained with 5 minutes sampling duration.

This paper presents the implementation for the first time of a porous SiOCH thin layer as stationary phase for silicon microcolumns for gas chromatography (GC). Deposition of the hybrid layer was obtained by plasma-enhanced-chemical-vapor-deposition (PECVD) with a porogen approach. Conformal and collective coating of the microcolumns was achieved and BTEX (Benzene, Toluene, Ethyl-benzene, o-Xylene) mixture could be separated with a good efficiency. This new process enables to consider a mass production of efficient microcolumns that is needed for the development of miniaturized, low cost, portable GC systems, e.g. for air quality monitoring.