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Biocapteurs Photoniques à Base de Silicium Poreux – BiP BiP

Submission summary

The aim of this project is the realization of photonic crystals based on the porous-silicon material system for biosensing applications. Combining the unique properties of planar photonic crystals with those of porous silicon allows for the design and realization of highly innovative photonic devices with significant impact for biosensing. Indeed, the porosity of the material enables the devices to yield a very high sensitivity for sensing applications, because the internal silicon surface available for biorecognition is very large compared to the planar surface sensors or the devices made in bulk materials. Moreover, photonic crystals offer high design flexibility and dispersion engineering. With convenient dispersion properties, highly resonant modes with very peculiar transmission/reflection properties can be designed. In particular, if excited by a beam normal to the photonic crystal membrane, such modes can lead to complete light reflection, whereas light is transmitted through the device if no resonant mode is excited. The proposed biosensors consist of planar photonic crystals realized in a porous silicon layer of low porosity on top of a high-porosity substrate. Their principle is simple: at the initial state, where no biorecognition process takes place inside the silicon pores, the resonant mode is excited. In this case, the photonic crystal behaves as a perfect mirror. No light is transmitted. If a biorecognition process takes place, molecular interaction occurs at the silicon surface inside the pores. The presence of the biomolecules induces a variation of the effective index of the porous silicon layers, which leads to a shift of the resonant mode. Light is transmitted through the structure. Therefore, the recognition process can be detected. The scientific program of the project is divided into 4 tasks: design of the photonic devices, technological realization, porous-silicon functionalization for biosensing, and optical characterization. The tasks are organized around the realization of 2 successive demonstrators, the first one for use in reflection, the second one for use in transmission. The design task concerns the modelling of porous-silicon planar photonic crystals supporting a resonant mode with the properties described above. After a general study is performed, the devices will be designed to work in aqueous environment and to be highly sensitive to index variations. This work is based on the expertise of the INL, both on resonant modes in planar photonic crystals and on porous-silicon photonics. The technological realization of the devices involves 2 hurdles. The first one is the patterning of porous silicon necessary for the fabrication of the photonic crystals. The resolution of this hurdle will enable the realization of the first demonstrator on silicon substrate, for reflection measurements. The second hurdle is the bonding of the porous structure onto a glass substrate that will allow for the realization of the second demonstrator for transmission studies. These two technological processes will be developed at the Nanolyon platform and should have very high impacts beyond the frontiers of photonics. The task on porous silicon functionalization contains all the biochemical protocols required for the immobilization of probe biomolecules on the porous silicon walls. In case of a successful biorecognition process, the probe biomolecules strongly interact with the target molecules to detect. Two different biological interactions will be tested, DNA hybridization and antigen/antibody interaction. The technological hurdle consists in a strong limitation of the non-specific adsorption, i.e., in optimizing protocols to enable the target biomolecules to interact exclusively with the probes. Finally, the optical characterization will consist of various studies to perform a very complete investigation of the photonic devices and of their potential for biosensing: near-field characterization of the resonant modes, spectroscopic studies of the reflection (resp. transmission) properties of the first (resp. second) demonstrator. The devices will also be studied in aqueous environment. The technological challenge of this task will be the demonstration of biosensing in the photonic devices with in-situ measurements. To conclude, this project is very rich, both in terms of investigations of new photonic concepts and devices, and of developments and optimization of new technological and biochemical processes. It offers exciting perspectives in the areas of photonics, technology and especially biosensing.

Project coordinator

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


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Beginning and duration of the scientific project: - 0 Months

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