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Detection of Olfactory traces by orthoGonal Gas identification technologIES

Periodic Report Summary 1 - DOGGIES (Detection of Olfactory traces by orthoGonal Gas identification technologIES)

Project Context and Objectives:
Border security is one of the key security challenges to be taken up by Europe in the following years. In particular, the deployment of practical efficient means to detect hidden persons and illegal substances at border crossing points is instrumental in avoiding terrorism, human trafficking or smuggling.

The DOGGIES project aims at demonstrating (1) an operational movable stand alone sensor for an efficient detection of hidden persons, drugs & explosives, (2) the potential adaptation of this solution for the detection of a much wider range of illegal substances.

The project addresses trace detection: it relies on the combination of two technologies based on completely different physical principles, therefore qualified as “orthogonal”:
- Mid-Infrared (MIR) spectroscopy technology, based on photo-acoustic detection, which appears as the most powerful and promising to detect a very wide range of volatile organic compounds (VOCs); developments within DOGGIES mainly target the demonstration of a widely tuneable integrated MIR source coupled with a miniature photo-acoustic cell;
- Ion mobility spectrometry technology, more mature; developments within DOGGIES mainly target the use of non radio-active ionisation source.

One of the main operational challenges is to provide reliable detection in real environments, in particular with the presence of “interferents”. It is expected that the use of specific pre-concentrators on one hand, and the combination of the signal emerging from these “orthogonal technologies” by advanced software on the other hand will improve the detection reliability.
The project activities cover basic studies in physics and chemistry, as well as sensor engineering and field tests. More precisely, in order to produce a final demonstrator efficiently assessed in different relevant operating scenarios, the following main technical objectives must be achieved:
- Identify the operational specifications and the end-users requirements
- Identify the most relevant VOCs related to human, drugs and explosives or their precursors
- Demonstrate a widely tuneable MIR source, based on distributed feedback (DFB) quantum cascade lasers (QCL) arrays multiplexed thanks to silicon-based arrayed waveguide gratings (AWG)
- Demonstrate a miniature MIR photo-acoustic spectrometer (MIRPAS) module
- Demonstrate a portable Gas Chromatography-Ion Mobility Spectrometer (GC-IMS) module using a non-radioactive ionising source
- Demonstrate selective pre-concentration of the selected relevant VOCs
- Integrate finally in a single portable instrument MIRPAS, GC-IMS, pre-concentrator and gas sampling with data acquisition and fusion software.

Project Results:
The definition of the system requirements and specifications and of three use case studies (for final prototype assessment) was completed first through discussion with potential end-users.
A first list of relevant VOCs was established through a careful examination of the literature. Because precise data are crucial for the development of our system, 158 absorbance IR spectra were recorded.
This enables the selection of two IR bands of interest, 100cm-1 broad around 7.4µm and 9.1µm. The suitable QCL heterostructures were designed, grown and processed. By adding a top metallic grating,. Multi-DFB QCL arrays exhibiting mono-frequency room temperature (RT) pulsed operation at 7.4µm with a high 90% lasing operation yield and tuning range over 50 cm-1 were obtained. The development of an InP:Fe-based buried technology was then completed in order to obtain CW operation above RT. In parallel MIR waveguides and AWG, based on a Si/SiGe graded index technology, were designed, processed and characterized. Passive waveguides exhibit losses lower than 2dB/cm in the 3 to 7.4 µm range. The wavelength selection capabilities around 7.4µm of the AWG were validated, with a very small discrepancy to the theory. For the higher targeted wavelengths, new Ge/SiGe waveguides were designed, fabricated and are currently under test. A first hybrid assembly of a QCL array and an AWG was demonstrated.
A miniaturized photo-acoustic cell with readout interferometers was also developed: its new design based on a dual cantilever system was validated through different breadboard demonstrators, having an estimated sensitivity in the low ppb-level in a time frame close to real-time measurement.
Our ion mobility spectrometer was also optimized. Different ionisation sources, including ß-radiation sources, UV light and an innovative electron emitter, were investigated. Tritium ß-radiation sources were chosen, ensuring high sensitivity and selectivity.
Significant progress was also done on the pre-concentrator building block of our system. Four different phosphonate cavitand hosts were synthesized and their recognition properties towards the selected molecules were tested via NMR titration and GC-MS experiments. Taking into account the operational parameters of the final system and some geometric constraints, MEMS pre-concentration devices were designed and a first batch is expected to be completed and functionalised soon.
The data acquisition platform and its connectivity have been determined. Raw data processing techniques have been investigated in bibliographic and experimental spectra, and have been included in the software module. Pre-processing analysis and preliminary algorithmic training show that mean centering and unit variance shall apply in operation with narrow spectral region information, disregarding any concentration information. The first results on Support Vector Machine training and prediction algorithm have been released. Multiple compound predictions within the same sample may be tricky and with low prediction accuracy.
Major intermediate tasks towards system integration were also completed. The technical and functional specifications for the gas sampling and treatment system as well as the design of gas handling system ensuring chemical and operational compatibility of the sample were established and the suitable materials and tools selected. A suitable sampling protocol matching functional requirements and sensors performances was then defined. A possible design of overall system pneumatics was proposed, the sniffing interface role and functionalities clarified, and the interface between gas sampling system and gas analyzers defined. Sensors mechanical and pneumatic features have been deepen and analyzed. A first mechanical design was finally implemented which highlighted the real applicability of the identified sampling solutions together with a need of further detailed specifications on single sensors mechanics.

Potential Impact:
After 18 months, the main building blocks required for the development of an operational movable stand alone sensor detecting efficiently hidden persons, drugs & explosives, are nearly in place. It is expected that this final instrument will be able to complement the dogs currently used by the canine units of the police force, in operations in urban or remote areas such as border and custom points.
In addition to this reliable, accurate and flexible system performing trace detection, many other products developed in the project could have a quick valorisation and a real impact:
- Two widely tuneable, low noise, continuous wave, compact MIR sources, allowing new detection strategy, commercially available before the end of 2014. Customised versions could be delivered in 2015.
- Miniaturized, discrete sampling photo acoustic cell as a next generation upgrade to existing product lines, reducing the whole footprint of the industrial gas analysers and allowing transportability for more challenging measurement sites.
- Dual-cantilever detection with miniaturized electronics enabling extreme sensitivity and multi-gas detection in a compact hand-held gas analyser.
- Autonomous and portable IMS-based trace gas detector.
- Selective and specific cavitand-based receptors to be used as pre-concentrator materials to enhance selectivity and sensitivity of analytical sensing devices.
- MEMS pre-concentration cartridges with increased sampling flow to reduce pre-concentration time.
- Software module for VOC chemometric analysis, with an optimized pre-processing of the relevant data of the compounds of interest, in order to be more efficient in prediction capabilities than the competitive products of general purpose.
- New method for pre-concentrators integration within IMS pneumatics which will give the possibility to either use standard injection loop methodology or to dynamically foster pre-concentrator selectivity to feed the chromatographic column.
- System for simultaneous distribution of gas sample to different analyzers by parametric configuration.

Apart from the above exploitable products, the project should also bring a significant contribution to the "lab-on-the-chip" domain, by addressing some key breakthrough objectives towards a fully optical lab-on-chip multi-gas analyzer, and have an impact in other domains than homeland security. Trace gas analysis markets are indeed now starting to emerge for a wide number of application niches presenting a strong societal impact: environment, health-care (health monitoring through breath or “human odours” analyses), scientific instrumentation, food safety, ... Such markets are driven by the demand of the citizen for increasing control and understanding of the impact on environment of industries, increasing safety regulations world-wide and deploy early stage medical diagnosis strategies. All these applications are requiring a new class of tools where size, weight and cost are key figures of merit.

In order to promote the project visibility and its results among the scientific communities and potential end-users first actions were overtaken during the first eighteen months (publications, posters, brochures and flyers to be distributed at exhibitions and conferences …). In particular a first workshop was organized in June 2013, gathering some potential end-users and representatives of many European projects involved in related security issues and detection techniques.
These dissemination actions were important in order to make the scientific and industrial community aware of the work, to enable them to understand the concepts and potential benefits and to obtain critical feedback from them to assess the overall approach. All these actions will contribute to increase the impact of the project.
Our DOGGIES web site, was also set up to support the external dissemination.

List of Websites: