Description du sujet de thèse

This project aims to develop a portable microanalyser dedicated to the analysis of biogenic volatile organic compounds (VOCs) in the air. This microanalyser will comprise two complementary modules for measuring non-soluble (apolar) and water-soluble (polar) species. The first module will be a miniaturised gas chromatograph (μGC), incorporating a micro-preconcentrator filled with a specific adsorbent and a set of micro-detectors (Photoionisation Detector (PID), Discharge Photoionisation Detector (DPID), etc.). The second module will operate in three stages: trapping soluble biogenic VOCs in an aqueous solution containing one or more pro-fluorophores, the selective reaction between the pro-fluorophore and the targeted molecules, and fluorescence detection of the reaction products.
As part of this thesis and in collaboration with several academic and industrial partners, the PhD student will be actively involved in: i) the design and manufacture of a photoionisation discharge microdetector (μDPID) and then of the μGC as a whole; ii) the adaptation of the second module (already used for the analysis of formaldehyde) for the analysis of soluble biogenic VOCs. The PhD student will also be responsible for manufacturing gas-phase calibration equipment for the targeted molecules using a methodology developed at ICPEES. Finally, the analytical performance of the two microanalyser modules will be evaluated under controlled laboratory conditions and then during field campaigns.

Contexte de travail

Laboratory context

The group of Analytical Chemistry and Materials for Environment and Health develops analytical methods for the detection of organic molecules mainly in the air but also in other environmental matrices (water, soils). The activities of the team are structured around 3 research axes:
Axis 1: On-line analytical methods via microfluidic devices for the quantification of air pollutants
Axis 2: Off-line analysis methods via chromatographic techniques
Axis 3: Adsorption study of organic molecules on various materials

This research project falls mainly within the scope of Axis 1. On-line methods combine sampling, species separation or selective derivatization reaction and near-real time detection. Microfluidics allows to obtain compact and portable devices.

Project context

This thesis will be funded as part of the European senseApest project coordinated by Stéphane Le Calvé (ICPEES, thesis supervisor) and involving 11 European partners (9 academic and 2 industrial). A summary of the senseApest project is given below.

The current plant inspection process is labour intensive due to visual assessments, low detection throughput and the need for physical sampling for molecular- or antibody-based detection kits. SenseApest will address these challenges by screening imported plant material systematically and efficiently with a non-contact portable detection unit (PDU), based on volatile organic compound (VOC) emissions.
Plants release VOCs in response to pest attacks, while pests emit their own distinctive VOCs. In senseApest, we propose to exploit these VOC biomarkers to develop a high throughput PDU equipped with VOC sensors, an algorithm, and a database. The PDU will enable rapid (<15 min), non-invasive and non-destructive screening of imported plant material for serious pests.

The project emphasizes high-accuracy, user-friendliness, cost and time-efficiency, and portability in the design of the PDU. Two analytical modules will be developed to detect a wide range of VOCs, adding a layer of specificity to broaden the spectrum of detectable pests. Miniaturized components will be integrated into the PDU, ensuring high analytical performance while maintaining portability.

The PDU will be validated into operational environments (TRL7). The collected data will train an algorithm in recognizing pest specific VOC biomarkers, enhancing diagnostic accuracy and applicability. The project aims to reduce false positives and false negatives in pest diagnostics while providing a method prioritizing efficiency in terms of analysis time and unit cost. Ultimately, the PDU is intended to be a cost-effective, user-friendly, adaptable, and efficient tool for plant health inspectors during import controls. To achieve this, a multi-actor interdisciplinary approach will be implemented.

Adopting the PDU is expected to save the EU €0.31–1.08 billion a year, while inspecting 90% of imported plants to limit the risk of plant pest invasions.

Candidate profil
General, theoretical, or disciplinary knowledge:
- Analytical chemistry (in-depth knowledge);
- Gas chromatography (in-depth knowledge);
- Instrumentation and measurements (thorough knowledge);
- Air Pollution;
- Materials Chemistry;
- Materials characterization techniques;
- Spectroscopy (fluorescence);
- English: B1 level or better

Knowledge of the professional environment:
- Organization and functioning of higher education and public research

Operational skills:
- Write reports or technical documents;
- Use the computer tools necessary for the control of analytical equipment and data processing;
- Develop an analytical method;
- Take into account the validity and limits of the characterization method used;
- Apply the rules of hygiene and safety;
- Work in a team;
- Communicate with experts in his/her field;
- Develop a technical specification.

Doctoral School (ED 222) requirements for thesis registration
Average in Master 1 and 2 above 12/20 (provide CV with grades, class ranking and average for each year (including BAC).

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

no specifics risks and constraints