Structure

biomimetic structures

Nature uses structure to achieve or enhance a certain function. Every shape, every bump, every branching point you can see in the natural world is there because it supports a certain function. This section groups EPFL’s research projects that get inspired by natural structures to design materials that are energy efficient, adaptable, biodegradable etc.

Since, structure leads to functions, structural properties are important aspect of research project working on Self-assembly, Self-healing and Self-cleaning, Sensing and Vision.

Spider silk inspired hierarchically structured supramolecular elastomers

Supramolecular networks that make use of specific non-covalent interactions furnish elastomer materials with superior processing and self-healing properties. However, they typically lack the hierarchical structure formation on different length scales observed in biomaterials that could be employed to tailor their mechanical properties. We prepared novel supramolecular materials based on oligopeptide-modified polymers that gave rise to “interpenetrating supramolecular networks”, that is, topologically independent networks with non-covalent interactions as network nodes. These materials displayed excellent energy dissipation.

Research Lab: prof. Holger Frauenrath, The Laboratory of Macromolecular and Organic Materials

 

Biologically-inspired hybrid block copolymers

Our research activities focus on conjugates of synthetic polymers and biologically-inspired peptide sequences. The peptide sequences are adapted from protein structures and direct the structure formation of the synthetic polymer. The use of such peptide sequences offers several unique advantages. First of all, due to the very specific folding and organization properties of the peptide sequences, they allow the organization of synthetic polymers in complex, hierarchically-organized structures that are very difficult to generate otherwise (see Self-assembly page). Secondly, the structure and properties of peptide – synthetic hybrid block copolymers can be manipulated by single amino acid “mutations” in the peptide segments. The peptide sequence of the hybrid block copolymers cannot only be used to drive structure formation, but can also be used to encode specific functionalities. This is a subject of ongoing research efforts.

Research Lab: prof Harm-Anton Klok, Polymers Laboratory

 

Composites that mimic bone and cartilage structures for faster tissue regeneration

Aim of the projects are to develop degradable and biocompatible scaffolds for tissue engineering. Bioresorbable scaffolds, i.e. porous constructs, seeded with the appropriate type of cells will provide a template for tissue regeneration, while slowly resorbing, to finally leaving no foreign substances in the body, thus reducing the risk of inflammation and offering more cost effective solutions. Polymers are combined with ceramic prior to be physically foamed or fibres are placed by 3D printing to elaborate various porous and anisotropic biocomposites.

Research Lab: prof. Pierre-Etienne Bourban, Laboratoire de technologie des composites et polymères, in collaboration with the Laboratory of Biomechanical Orthopedics (LBO) at EPFL and the Centre Hospitalier Universitaire Vaudois (CHUV).

 

Natural fibre composites

The research goes towards processing and enhanced properties of natural fibers and their biocomposites. We mainly work with flax and cellulose composites. The friction mechanisms in between the layers of each natural fibre explain the good damping performance of some composites used in sport applications for instance. Nano fibrillated cellulose is combined to hydrogels to offer a unique compromise of stiffness and damping in biomedical applications such the replacement of damaged nucleus pulposus in intervertebral disks.

Research Lab: prof. Pierre-Etienne Bourban, Laboratoire de technologie des composites et polymères

 

Turtle shell inspired alpine skis

These alpine skis change stiffness in response to the skier’s position. EPFL researchers helped develop the new skis thanks to a mechanism that mimics turtle scales.

The ideal ski can withstand high levels of pressure in turns yet also be easy to maneuver. These two features usually require two different types of skis: the rigid skis preferred by expert skiers or the flexible ones that intermediate skiers opt for. But a new type of ski offers a two-in-one solution thanks to a design based on turtle scales. These skis are easy to maneuver while entering and exiting turns but stiffen up in the middle of turns to improve the skis’ grip on the snow. The scales of a turtle interlock, like a jigsaw puzzle, and are connected by a polymer. When turtles breathe, the scales separate slightly and the shell becomes flexible. But when an external shock occurs, the shell tightens and stiffens. It struck me immediately that we could build these features into skis. This ‘turtle shell’ design is the result of a joint effort of EPFL, the Institute for Snow and Avalanche Research (SLF) in Davos and Stöckli, the Swiss ski manufacturer.

Research Lab: prof. Veronique Michaud, Laboratoire de technologie des composites et polymères

 

Biomimicking micro/nanopatterned surfaces – 3D Nanolithography

LMIS1 has recently installed a brand new, ultra-high resolution 3D thermal scanning probe nanolithography (th-SPL) tool NanoFrazor. In th-SPL, the heated probe of few nm in radius in contact with the sample induces local mechanical and chemical surface modifications. Such technique allows fabrication a variety of 3D topographies to high accuracy. These structures are in need in printed optics, nanophotonics, medicine and can be used for generation of the templates for nanoimprint lithography.

Research Lab: Jurgen Brugger, Microsystems Laboratory 1