Drosophila wing expansion for soft robotic application
When an insect emerges from its pupae, its wings expand in a couple of minutes, prompted by the injection of hemolymph in a network of folded veins[1-3]. This rapid deployment exceeds our best engineering designs. The main goal of the project is to characterize the wing expansion in Drosophila, to develop a fundamental understanding of the underlying physical mechanisms in order to describe the fluid-structure interaction between the hemolymph injection and the deformation of the vein network and explain how the inflation of an individual vein, organized in a network, guides the expansion of a structure. The objective of the project is twofold: to understand the natural process through a biomechanics description on the one hand and to transfer the biological observation to prototypes on the other hand, opening the door for soft robotic application[4-7] from compliant medical devices to deployable wings for ultra light drones.
Morphogenesis, bioinspiration, biomechanics, fluid-structure interaction, soft robotic
The primary research objective of the project is to identify and build a fundamental understanding of the wing expansion of emerging insects and to design laboratory prototypes that capture their essential physical ingredients, opening the door for engineering applications. In addition, we will aim to model the fluid structure coupling between the viscous loading and the deformation of the structure to understand the dynamical properties of the structure
Proposed approach (experimental / theoretical / computational)
We will characterize the wing deployment in Drosophila (in the wild type and mutants presenting deployment anomalies[3,8]) and record the temporal variation of the internal pressure during the expansion. Hand in hand with macroscopic observations of the unfolding process, we will develop model experiments using digital fabrication and rapid prototyping techniques to reduce the complexity of the biological system to its essential physical ingredients and to rationalize the actuation processes. We will assess experimentally the fluid-structure interaction between the viscous loading and the deformation of the vein during the expansion and build a theoretical model to describe the dynamic first at the level of one vein and then generalizing for the network. We will eventually address the inverse problem using topological optimization to find the optimal vein networks to program the mechanical properties and dynamic of the structure.
The proposed research is interdisciplinary by nature, spanning organismic biology, theoretical mechanics, materials science and engineering and will link traditionally disparate fields, providing the perspective of theoretical mechanics to the field of biology. The characterization of the wing expansion in drosophila will be studied at IBDM under the guidance of Raphaël Clément within the team Physical approach to cell dynamics and tissue morphogenesis. The model system of deployable structure will be developed at IUSTI under the guidance of Joël Marthelot who works on slender structures and bioinspired actuation of soft structures within the Biomechanics team. In addition, the PhD student will work in close collaboration with Marie-Julie Dalbe from IRPHE, who is a specialist of fluid mechanics of viscous flow in poroelastic structures and Cédric Bellis from LMA who works on topological optimization and inverse problem.
Candidates with either Physics or Engineering backgrounds and research achievements in the general area of biomechanics, soft/compliant mechanics or fluid mechanics are welcomed to apply. The following areas of experimental expertise are particularly welcomed: biomechanics, rapid prototyping, micro-fabrication, material science and mechanical testing. In addition, an appreciation for scaling analysis, theory and computation is a plus.
References G Pass. Beyond aerodynamics: The critical roles of the circulatory and tracheal systems in maintaining insect wing functionality. Arthropod Struct. Dev., 47(4), 391-407, 2018.
 M Tögel, G Pass, and A Paululat (2008). The Drosophila wing hearts originate from pericardial cells and are essential for wing maturation. Dev. Biol., 318(1), 29-37, 2008.
 JA Kiger, JE Natzle, and MM Green. Hemocytes are essential for wing maturation in Drosophila melanogaster. Proc. Nat. Acad. Sc. USA, 98(18), 10190-10195, 2001.
 RF Shepherd, F Ilievski, W Choi, SA Morin, AA Stokes, AD Mazzeo, X Chen, M Wang, and GM Whitesides. Multigait soft robot. Proc. Nat. Acad. Sc. USA, 108(51):20400–20403, 2011.
 E Siéfert, E Reyssat, J Bico, and B Roman. Bio-inspired pneumatic shape-morphing elastomers. Nature Mater., 18(1):24, 2019.
 AS Gladman, EA Matsumoto, RG Nuzzo, L Mahadevan, and JA Lewis. Biomimetic 4d printing. Nature Mater., 15(4): 413, 2016.
 W Hu, GZ Lum, M Mastrangeli, and M Sitti. Small-scale soft-bodied robot with multimodal locomotion. Nature, 554(7690):81, 2018.
 RP Ray, A Matamoro-Vidal, PS Ribeiro, N Tapon, D Houle, I Salazar-Ciudad, and BJ Thompson. Patterned anchorage to the apical extracellular matrix deﬁnes tissue shape in the developing appendages of drosophila. Dev. Cell, 34(3): 310–322, 2015.
 MP Bendsøe and O Sigmund. Optimization of structural topology, shape, and material, volume 414. Springer,1995