Mid-VOC : Photonic integrated sensor based on porous materials for Mid Infrared detection of volatile organic compounds

Context

The MID-VOC project aims at developing a highly innovative integrated optical spectroscopic sensor to detect volatile organic compounds (VOCs) in the Mid-Infrared from exhaled breath. Indeed VOCs exhibit broad absorption features in this wavelength range. These sensors are based on optical waveguide made of porous silicon (PSi) to take advantage of the opened pores in order to obtain a low limit of detection. To ensure selective detection of VOCs, two types of functionalization of PSi will be considered : an inorganic approach by using metal oxide particles whereas the second approach will use self-assembly monolayer (SAM). So, the project will consist in the design, functionalization, processing and characterization of mid-IR sensors based on functionalized porous silicon layers. The development of this optical sensor will be used to develop breath analyzing set-up with high accuracy for non-invasive, real-time and point-of-care disease diagnosis and metabolic status. At the end of the project, we will provide a highly sensitive and specific analytical device based on our optical platform with a technology at the TRL 4.

Goals

The MID-VOC project aims to develop an optical integrated sensor for the detection of VOCs in the mid-infrared (Mid-IR) wavelength range. The target wavelengths will be more particularly focused between 2 and 8 µm due to the silicon transparency. This project will consist in the chemical functionalization, design, processing and characterization of optical integrated sensor based on functionalized porous materials films by using surface detection. In the framework of this project, the developed transducers will consist in integrated spiral waveguides based on porous silicon to specifically capture the VOCs of interest thanks to specific functionalizations. This optimization of the transducer structure will take advantage of the opened pores to diffuse the target molecules toward the volume of the transducer to obtain a high sensitivity and a low limit of detection due to the important surface specific of porous layer. A preliminary experimental study was achieved at 7.3 µm to obtain porous silicon integrated ridge to observe the light propagation in Mid-Infrared. This optical platform has thus to be integrated in a complete optical device including a microfluidic system, a laser injection system by using a tuneable QCL. Exploiting the miniaturization of the optical platform and taking advantages offered by the microfluidic technology, the aim is to provide a miniaturized Lab-On-a-Chip device to detect several VOCs at different Mid-IR wavelengths. The waveguide platform will be designed to allow single mode propagation. The development of this sensor will enable continuous in-situ analysis in real-time without the need to collect samples. The project takes up three main challenges that will have to be reached :- Challenge of the design implementation to define the optimal geometrical parameters linked to the optical properties of the materials (especially the refractive indexes and also technological compatibility to obtain low optical losses (< 3dB/cm in the Mid-IR wavelength range). – Technological challenge to implement the optical structure with different steps of chemical functionalization- Integration in microfluidic system for implementation- Challenge of the sensing study of different VOCs to test

Scientific production

Partners

Foton-SP – IEMN

Coordinator

Joël CHARRIER (Foton-SP)

Funding

ANR (272 k€)

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