Description of the thesis topic

Context and objective of the project: Energy harvesting devices provide a battery-less solution by scavenging energy from ambient sources and converting them into electrical power. The ability to deliver sustainable power to a biomedical device via energy harvesting is attractive as it reduces battery costs and disposal issues, and the need for complex wired systems. This is relevant to micro-sensors within medical implants. However, current systems are only efficient over a restricted frequency range, and elastic coupling of ultrasonic energy recovery devices can be limited.
The objective of the PhD thesis will be the conception of an innovative design of metamaterials (MMs) and/or phononic crystals (PCs) to: (i) efficiently guide, confine / trap, and dissipate vibratory / sound energy and (ii) improve electromechanical conversion efficiency for health-related applications.
Two approaches will be mainly explored, namely an active and a passive one. The first includes exploring the potential of piezoelectricity, magnetoelasticity, and/or photo-responsiveness, combined, when possible, with topological protection to enhance both the guiding and absorption of mechanical vibratory energy in the structure for conversion into (electrical) energy. The second approach, based on passive MMs/PCs, may involve investigating local resonances, the inertial amplification mechanism, point masses, or rotational inertia elements. Fractal and hierarchical organizations of the unit cells will also be explored.

Work Context

Main tasks and responsibilities: The candidate will work in a collaborative way in the framework of the European project HORIZON-MSCA-DN-[2022] MetacMed (« Acoustic and mechanical metamaterials for biomedical and energy harvesting applications ») under the supervision of Dr. M. Miniaci (IEMN). He/she will develop a novel topological MM-based energy-harvesting device. He/she will investigate the manipulation of the dispersive properties of elastic MMs through the integration of functional elements into the unit cell – piezoelectric materials, modifying the connectivity of a PC by using magnetoelasticity or photo-responsivity, etc.
More specifically, he/she will need to: (i) conduct an in-depth literature review to identify the state of the art of PCs/MMs for the aforementioned applications, (ii) develop analytical and/or numerical models to perform simulations aimed at finding promising configurations for PCs/MMs capable of controlling waves at multiple frequencies (mainly in the audible range and those generated by walking); (iii) evaluate the performance of the designed PCs/MMs; (iv) optimize the structural design based on the predicted dynamic behavior; (v) participate in the fabrication of the samples; and (vi) perform measurements to validate the designs.

Required competences: The ideal candidate should have a master's degree in engineering, physics or similar disciplines. Knowledge of numerical modelling and a strong background in structural mechanics and wave propagation in periodic media is a plus.

Required soft skills: The ideal candidate is able of team playing, of rigorous and clear reporting to the supervisor(s), of independent thinking and working in autonomy under assigned tasks and towards specific objectives.

Location: The Institute of Electronics, Microelectronics and Nanotechnology (UMR CNRS 8520 - https://www.iemn.fr/en/) is in Villeneuve d'Ascq, near the city of Lille (France). With a total staff of more than 500 people, the institute has a wide range of research activities from physics to materials science, micro and nanotechnology.
Planned secondments: Amazemet (3 months) for sample realization and Empa (6 months) for experimental activities.

Application: The candidate is asked to provide the following documents (only online applications – CNRS website – will be accepted):
1) A cover letter (max 2 pages) explaining why he / she is applying to this position.
2) A detailed CV.
3) Two to three reference letters.

Start date: As soon as possible (36 months).

Funding: European project HORIZON-MSCA-DN-[2022] MetacMed (« Acoustic and mechanical metamaterials for biomedical and energy harvesting applications »).

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

n/a