This PhD project aims to develop hybrid acousto-plasmonic metasurfaces for label-free, high-sensitivity cell sensing, by combining surface acoustic waves (SAWs)1, localized surface plasmon resonances (LSPR)2, and controlled photothermal effects3 into a multimodal platform. 
Acoustic phonons are quanta of lattice vibrations within a material, playing a crucial role in determining its thermal and mechanical properties whereas surface plasmons are collective oscillations of free electrons at the interface between a metal and a dielectric. These oscillations can be excited by light and are highly sensitive to changes in the surrounding environment, making them ideal for sensing applications. Finally, metasurfaces allow total control of light by modifying the phase and amplitude of the incident electromagnetic field using nanostructures array. Thus, hybrid acousto-plasmonic metasurfaces could serve as compact, active interfaces capable of mechanically and optically interacting with living cells, enabling the precise study of cell–substrate interactions and mechanotransduction phenomena.

Understanding how cells respond to mechanical and thermal cues is critical not only for cell biology, but also for biomedical diagnostics and space health monitoring. In microgravity (e.g., on the ISS), symptoms of accelerated aging — such as muscle atrophy, bone loss, and immune decline — are observed, often linked to altered cellular mechanosensing. Hybrid acousto-plasmonic systems provide a way to study these effects in controlled conditions, offering insights into cell behavior under altered physical environments.

The proposed sensing platform is based on engineered metasurfaces fabricated with plasmonic and piezoelectric materials (titanium nitride (TiN), gold (Au), and lithium niobate (LiNbO₃). These materials offer a unique combination of advantages as TiN is a robust, CMOS-compatible plasmonic material with high thermal stability and excellent biocompatibility. LiNbO₃ is a widely used for generating high-frequency SAWs and Gold offers favorable surface chemistry for biological functionalization. This combination enable interaction with cells via mechanical, optical, and thermal channels, providing a rich sensing environment with dynamic tunability.

Previous work has demonstrated that SAWs and plasmonics can be used to tune wavefronts4. Indeed, plasmonic metasurface over acoustic substrate enabling the conversion of one physical waveform to another (electromagnetic waves to mechanical waves), leading the opportunity to highly sensitive interface. The add of photothermal effects consideration will affect signal enhancement and allow active modulation tool. Localized heating near the cell–substrate interface can influence membrane fluidity and lipid organization (modification of protein transport); adhesion dynamics; and cell viability (irreversible thermal effects threshold).

The project is divided in three main axes: the candidate will begin by using advanced multiphysics simulation tools (Comsol and Matlab) to model the complex coupling between SAW and SPR. These simulations, based on FEM and FDTD techniques, will ensure to have optimized design and improved sensitivity. Then, the PhD student will realized the hybrid metasurfaces sample by using high-resolution lithography (e-beam or nanoimprint). The interdigitated transducers (IDTs) will allow to generate surface acoustic waves (SAWs) in the MHz to GHz range based on simulation and previous design1. The plasmonic metasurface will be integrated on the sample to modulate the speed and act as transducer of the SAW. Measurements will include SPR shifts using angulo-spectral reflectivity and SAW performance via amplitude and frequency analysis. We will use relevant cell models like MeWo as proof of concept. It is eukaryotic cell line, similar to fibroblasts. These experiments will assess cell adhesion, spreading, and mechanosensitive responses under combined acoustic and thermal stimulation.

This project is expected to result in a new class of active metasurface biosensors that combine mechanical, optical, and thermal functionalities within a single platform. Offering high-resolution and real-time monitoring of biological processes, the platform will provide a deeper understanding of cell–material interactions under dynamically tunable physical stimuli. It will be relevant both on Earth and in space environments.

1. J. Bonhomme et al. “Numerical Characterization of Love Waves Dispersion in Viscoelastic Guiding-Layer Under Viscous Fluid”, Journal of Applied Physics (2020)
2. M. Vega et al.  “Plasmonic Film with Diluted Nanostructures for Light Energy Harvesting and Sensing,” ACS Appl. Opt. Mater, (2025)
3. J-F. Bryche et al., “Ultrafast Heat Transfer at the Nanoscale: Controlling Heat Anisotropy,” ACS Photonics, (2023) 
4. J. E. Holland, et al.  “Acoustoplasmonic Metasurfaces for Tunable Acoustic Wavefront Shaping with Polarized Light,” ACS Photonics, (2025)

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - jean-francois.bryche@cnrs.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!